Tecumseh TC Series User manual

This manual covers all TC, TCH 200 & 300 models.
Other illustrated Tecumseh 2-Cycle Engine, 4-Cycle Engine
and Transmission manuals; booklets; and wall charts are
available through Tecumseh.
For complete listing write or call
TC SERIES
2-Cycle
Engines
T E C H N I C I A N ' S H A N D B O O K
TECUMSEH
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CONTENTS
CHAPTER 1 GENERAL INFORMATION .............................................................................. 1
ENGINE IDENTIFICATION ...................................................................................................................... 1
OIL REQUIREMENTS .............................................................................................................................. 1
FUEL REQUIREMENTS .......................................................................................................................... 2
STORAGE ................................................................................................................................................ 3
CHAPTER 2 AIR CLEANERS ............................................................................................. 4
GENERAL INFORMATION ...................................................................................................................... 4
OPERATION ............................................................................................................................................. 4
TROUBLESHOOTING ............................................................................................................................. 4
SERVICE .................................................................................................................................................. 4
PAPER FILTER REMOVAL AND REPLACEMENT ................................................................................. 5
POLYURETHANE FILTER REMOVAL AND SERVICE ........................................................................... 5
CHAPTER 3 CARBURETORS AND FUEL SYSTEMS ....................................................... 6
GENERAL INFORMATION ...................................................................................................................... 6
OPERATION ............................................................................................................................................. 6
FUEL PRIMERS ....................................................................................................................................... 7
COMPONENTS ........................................................................................................................................ 7
TILLOTSON CARBURETOR ................................................................................................................... 8
TROUBLESHOOTING ............................................................................................................................. 9
TROUBLESHOOTING CARBURETION - TC SERIES .....................................................................10-11
TESTING ................................................................................................................................................ 12
SERVICE ................................................................................................................................................ 12
CARBURETOR PRE-SET AND ADJUSTMENT .................................................................................... 12
FUEL TANK SERVICE ........................................................................................................................... 13
CARBURETOR DISASSEMBLY ............................................................................................................13
CARBURETOR INSPECTION ............................................................................................................... 14
CARBURETOR ASSEMBLY ............................................................................................................ 14-15
CHAPTER 4 GOVERNORS AND LINKAGE ..................................................................... 16
GENERAL INFORMATION .................................................................................................................... 16
OPERATION ........................................................................................................................................... 16
COMPONENTS ...................................................................................................................................... 16
TROUBLESHOOTING ........................................................................................................................... 17
ENGINE OVERSPEEDING .................................................................................................................... 17
ENGINE SURGING ................................................................................................................................ 17
SERVICE ................................................................................................................................................ 17
GOVERNOR ADJUSTMENT ........................................................................................................... 17-18
CHAPTER 5 REWIND STARTERS .................................................................................... 19
GENERAL INFORMATION .................................................................................................................... 19
OPERATION ........................................................................................................................................... 19
TYPE I .................................................................................................................................................... 19
TYPE II ................................................................................................................................................... 19
COMPONENTS ...................................................................................................................................... 19
SERVICE ................................................................................................................................................ 19
DISASSEMBLY PROCEDURE .............................................................................................................. 19
ASSEMBLY PROCEDURE .................................................................................................................... 20
C Tecumseh Products Company
1998
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CHAPTER 6 IGNITION ....................................................................................................... 21
GENERAL INFORMATION .................................................................................................................... 21
OPERATION ........................................................................................................................................... 21
COMPONENTS ...................................................................................................................................... 21
TROUBLESHOOTING ........................................................................................................................... 22
TESTING ................................................................................................................................................ 23
SERVICE ................................................................................................................................................ 23
AIR GAP SETTING ................................................................................................................................ 23
SPARK PLUG SERVICE ........................................................................................................................ 23
CHAPTER 7 INTERNAL ENGINE AND CYLINDER ......................................................... 24
GENERAL INFORMATION .................................................................................................................... 24
OPERATION ........................................................................................................................................... 24
COMPONENTS ...................................................................................................................................... 24
TROUBLESHOOTING ..................................................................................................................... 25-26
TESTING ................................................................................................................................................ 27
ENGINE KNOCKS .................................................................................................................................. 27
ENGINE OVERHEATS ........................................................................................................................... 27
SURGES OR RUNS UNEVENLY .......................................................................................................... 27
MISFIRES ............................................................................................................................................... 27
ENGINE VIBRATES EXCESSIVELY .....................................................................................................28
LACKS POWER ..................................................................................................................................... 28
SERVICE ................................................................................................................................................ 28
GENERAL INFORMATION .................................................................................................................... 28
DISASSEMBLY PROCEDURE ........................................................................................................ 28-29
BEARING AND SEAL SERVICE ............................................................................................................ 30
ASSEMBLY....................................................................................................................................... 31-33
CHAPTER 8 ENGINE SPECIFICATION AND SEARS CRAFTSMAN
CROSS-REFERENCE ............................................................................................... 34
TC TORQUE SPECIFICATIONS............................................................................................................ 34
ENGINE SPECIFICATIONS ................................................................................................................... 35
SEARS CRAFTSMAN CROSS REFERENCE ....................................................................................... 36
CHAPTER 9 EDUCATIONAL MATERIALS AND TOOLS .......................................... 37-40
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CHAPTER 1 GENERAL INFORMATION
ENGINE IDENTIFICATION
TC engine identification numbers are stamped into the blower housing or blower housing base near the spark plug, or a
decal is permanently attached to the side of the blower housing (diag. 1-1).
Identification Decal
TC TYPE I ENGINE TC TYPE II ENGINE
SHORT BLOCK IDENTIFICATION TAG
SBV or SBH Identification number
SER 4201
SBV1543
1-1
1-3
Model
Number
Identification Decal
The engine identification decal will include the model
number, specification number, warranty code, and date of
manufacture (diag. 1-2).
The model number designation following TC (Tecumseh
Compact) indicate the cubic inch displacement of the
engine.TC 300 indicates a 3.0 cubic inch displacement.
The number (3133C) following the model number is the
specification number. The last two numbers and letter
character (33C) indicate a variation to the basic engine
specification.
Thewarrantycodeletter (B)indicatesthelength ofwarranty
that is supplied by Tecumseh.
TheDOM(DateofManufacture)orSerial Number indicate
the date the engine was produced.The first digit (5) is the
year in the decade (1995). The next three digits (114)
indicate the Julian build date (114 th day or April 24).The
letter designation indicates the line or shift on which the
engine was built at the factory.
Short blocks are identified by a tag marked SBH (Short
Block Horizontal) or SBV (Short Block Vertical) (diag.
1-3).
TC300 3133C (B) 5114G
CAUTION:THIS SYMBOL POINTS OUT IMPORTANT SAFETY INSTRUCTIONSWHICH IF NOT FOLLOWED
COULD ENDANGER THE PERSONAL SAFETY OF YOURSELF AND OTHERS. FOLLOW ALL
INSTRUCTIONS.
OIL REQUIREMENTS
TECUMSEH RECOMMENDS USINGTWO CYCLE OIL PART #730227, which is a premium blend that ensures cylinder
wall lubrication, mixes easy, does not separate and is specially formulated for use in air or water cooled two cycle
engines.
Tecumseh two cycle engines require the use of a NMMA TC-W3 or TC-WII certified oil.
The proper fuel mixture ratio of oil to gasoline for specific engines will be found in the owners operating instructions and
on the decal attached to the blower housing or fuel tank of the engine.
Serial Number or DOM
1-2
Date of Manufacture
or Serial Number
Warranty
Code
Specification
Number
1
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2
24:1 FUEL MIXTURE CHART ALLTC ENGINES
NOTE: DO NOT MIX FUEL IN ENGINE OR
EQUIPMENT FUEL TANK.
U.S. METRIC
Gas Oil To Be Added Petrol Oil To Be Added
1/2 Gal. 3.00 oz. 2 Liters 83 ml.
1 Gal. 6.00 oz. 4 Liters 167 ml.
2 Gal. 11.00 oz. 8 Liters 333 ml.
MIXING OIL AND GASOLINE PROCEDURE
1. Fill approved, clean container one quarter full with
the recommended gasoline.
2. Add the recommended amount of oil to the
gasoline.
3. Secure the cap on the container and shake the
container vigorously.
4. Removethecap,addtheremainderofthe gasoline,
secure the cap, re-mix.The fuel is ready to use.
FUEL REQUIREMENTS
Tecumseh Products Company strongly recommends the
use of fresh, clean, unleaded regular gasoline in all
Tecumseh engines. Unleaded gasoline burns cleaner,
extends engine life, and promotes good starting by
reducing the build-up of combustion chamber deposits.
Leaded gasoline, gasohol containing no more than 10%
ethanol, premium gasoline, or unleaded gasoline
containing no more than 15% MTBE (MethylTertiary Butyl
Ether), 15% ETBE (Ethyl Tertiary Butyl Ether) or 10%
ethanol, can be used if unleaded regular gasoline is not
available.
Reformulatedgasolinethatis nowrequiredin severalareas
of the United States is also acceptable.
NEVER USE gasoline, fuel conditioners, additives or
stabilizers containing methanol, gasohol containing more
than 10% ethanol, unleaded regular gasoline containing
more than 15% MTBE (Methyl Tertiary Butyl Ether), 15%
ETBE (EthylTertiary Butyl Ether) or 10% ethanol, gasoline
additives, or white gas because engine/fuel system
damage could result.
See “STORAGE” instructions in Technician’s Manual,
Operator’s Manual, or Bulletin 111.
For year round fuel stability in and out of season, use
Tecumseh's fuel stabilizer part number 730245.
FUEL ADDITIVES
Only fuel additives such as Tecumseh's fuel stabilizer part number 730245 or liquid varieties can be used when mixed
properly. For winter applications, Isopropyl alcohol fuel dryers may be used in the fuel system but must be mixed at
the proper ratio recommended by the manufacturer. NEVER USE METHANOL BASED DRYERS.
Gasoline and oil containers must be clean, covered, and rust-free. Old gas or fuel contamination can restrict or block
fuel filters, and small fuel ports and passages in the carburetor. If the engine is to be unused for 30 days or more see
"Storage" for fuel system instructions.
TUNE-UP PROCEDURE
The following is a minor tune-up procedure. If the engine does not perform properly after the tune up is completed,
consult the "Troubleshooting Engine Operation Chart" found in Chapter 7. Repair procedures are listed in each chapter.
CAUTION: REMOVETHE SPARK PLUGWIRE BEFORE DOING ANY SERVICEWORK ONTHE ENGINE.
1. Service or replace the air cleaner as necessary.Usetheapplicableprocedure foundin Chapter 2 under "Service".
2. Removethe fuel from the fuel tank byrunning the engine until stopping or draining into an approvedfuel container.
3. Remove the fuel tank and blower housing to clean all debris from the air intake screen, cylinder cooling fins,
governor and carburetor linkage.
4. Replace the blower housing and check all remote linkage for proper adjustment and operation.
5. Check to see that the engine is properly secured to the equipment. On rotary lawnmowers, balance the blade
and check the blade hub and crankshaft key for wear. Replace as necessary. Torque the bolts to the correct
specification.
6. Replace the spark plug with the correct replacement by using the Master Technician's Parts Manual. Set the
spark plug gap at .030" (.762 mm) and install it in the engine.Tighten the spark plug to 230 inch pounds (2.6 Nm)
of torque.If a torque wrench isn't available, screw the spark plug in as far as possible by hand.Use a spark plug
socket or wrench to turn the spark plug 1/8 to 1/4 turn further if using the old spark plug, or 1/2 turn further if a
new spark plug is used. Reinstall the spark plug wire.
1-4
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3
7. Fill the fuel tank with the proper fuel/oil mix.
8. Start the engine and allow it run 3 - 5 minutes to reach operating temperature.Adjust the carburetor if necessary
(see Chapter 3 under "Service" for the final idle mixture adjustment procedure) and set the engine R.P.M.(s)
according to the specification number found on microfiche card # 30 or computer parts look up system.
STORAGE (IF THE ENGINE IS TO BE UNUSED FOR 30 DAYS OR MORE.)
CAUTION: NEVER STORETHE ENGINE WITH FUEL INTHETANK INDOORS OR IN ENCLOSED, POORLY
VENTILATED AREAS,WHERE FUEL FUMES MAY REACH AN OPEN FLAME,SPARK OR PILOT LIGHT AS
ON A FURNACE,WATER HEATER, CLOTHES DRYER, OR OTHER GAS APPLIANCE.
Gasoline can become unstable in less than 30 days and form deposits that can impede proper fuel flow and engine
operation. To prevent deposits from forming, all gasoline must be removed from the fuel tank and the carburetor. An
acceptable alternative to removing all gasoline is adding a fuel stabilizer to the gasoline such asTecumseh part number
730245.A fuel stabilizer is added to the fuel tank or storage container.Always follow the mix ratio and mixing procedure
found on the stabilizer container. Run the engine at least 10 minutes after adding the stabilizer to allow it to reach the
carburetor.
DrainingThe Fuel System
1. Remove all gasoline from the fuel tank by running the engine until the engine stops, or by draining the fuel tank
by removing the fuel line at the carburetor. Be careful not to damage the fuel line or the carburetor fitting.
CAUTION: DRAIN THE FUEL INTO AN APPROVED CONTAINER OUTDOORS, AND AWAY FROM ANY
OPEN FLAME OR COMBUSTIVE SOURCE. BE SURETHE ENGINE IS COOL.
2. If "Gasohol" has been used, complete the above procedure and then put 2 ounces (60 ml) of the recommended
fuel / oil mixture using regular unleaded gasoline into the fuel tank.Run the engine until it stops due to a lack of
fuel.If "Gasohol" is allowed to remain in the fuel system during storage, the alcohol content may cause gaskets
and seals to deteriorate.
Oil Cylinder Bore
1. Remove the spark plug wire from the spark plug. Pull the starter handle slowly until resistance is felt due to
compression pressure, then stop. Slowly release starter tension to prevent the engine from reversing due to
compression pressure.
2. Remove the spark plug, squirt 1/2 ounce (15 ml.) of clean 2-cycle engine oil into the spark plug hole.
3. Cover the spark plug hole with a shop towel and crank the engine over, slowly, several times.
4. Replace the spark plug and tighten (see step # 5 under Tune-Up Procedure for proper spark plug torque). Pull
the starter handle as performed in step # 1.The piston position blocks the cylinder ports, preventing atmospheric
air from entering and oil from leaving the cylinder bore during storage.
5. Replace the spark plug wire on the spark plug.
TUNE-UP PROCEDURE (continued)
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4
CHAPTER 2 AIR CLEANERS
TROUBLESHOOTING
If the engine's performance is unsatisfactory (needs
excessive adjustments, starts smoking abnormally, loses
power),thefirstcomponent to be checked is the aircleaner.
A dirt restricted or an oil soaked filter element will cause
noticeableperformance problems.A polyurethane element
may be cleaned following the service procedure listed
under"Service" inthischapter.Apaper-type airfiltershould
onlybereplaced.Followthe procedure listed in the service
section in this chapter for replacement. Re-try the engine
after filter replacement or service. If the problem persists
after filter service, see Chapter 7 under "Troubleshooting"
for additional causes.
SERVICE
Cleaning and oiling the polyurethane element (diag. 2-1)
is recommended every three (3) months or every 25
operating hours. If the engine is used in extremely dusty
ordirtyconditions, the filter mayrequire service every three
hours or as often as necessary to maintain proper engine
performance.
Polyurethane type filters require re-oiling after extended
storage due to oil migration out of the filter.
A paper type element (diag. 2-2) should be replaced once
a year, every 100 operating hours, or more often if used in
extremely dusty conditions. Use only original factory
recommended replacement filters.
NOTE: DO NOT ATTEMPT TO CLEAN OR OIL PAPER
FILTERS.
Air Cleaner Screen
Polyurethane Filter
2-1
2-2
Air Cleaner
Collar
Clamp
Cover
GENERAL INFORMATION
The air cleaner is designed to eliminate dust and dirt from the air supply. Most models of 2-cycle and 4-cycle engines
use an air cleaner except engines that run in clean environments like snow throwers or ice augers.On these applications,
a filter is not necessary and could collect snow or moisture and prevent proper engine operation.On most applications,
filtered air is necessary to assure abrasive particles are removed before entering the combustion chamber. Dirt allowed
into the engine will quickly wear the internal components and shorten the life of the engine.
Tecumseh engines use either a polyurethane or a paper type air filter system. A polyurethane pre-filter or a flocked
screen may be used in conjunction with the main filter. Extremely dirty operating conditions may require frequent filter
cleaning or replacement.
OPERATION
The outer cover holds the air filter element(s) and prevents debris from entering the filter box.The air supply is filtered
through the pre-filter if equipped, filter element (polyurethane or paper), and a flocked screen if equipped. Pre-filter
elements do not extend the recommended air filter service intervals listed under "Service". However; in extremely dirty
operating conditions a pre-filter element may increase the run time of the engine before the filter becomes restricted (not
to exceed the service recommendations), and service on the filter is necessary.
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Paper Filter Removal and Replacement
1. Remove the polyurethane pre-filter (if equipped) from
the air filter.
2.Inspectthefilter(s) fordiscolorationordirt accumulation.
(For the polyurethane pre-cleaner service see step #
5 under "Polyurethane Filter Removal and Service").
If either condition is present, replace the paper type
filter using the following steps.
3. Loosen the clamp and slide the clamp toward the air
filter. (diag. 2-3)
4.Slide the air filter and clamp off the carburetor adapter.
Discard the old filter and keep the clamp.
5. Apply a thin layer of silicon sealant to the outside of
the air cleaner adapter.
6. Install the clamp on the new air filter, slide the filter
assembly onto the carburetor adapter as far as it will
go.
7.Slide the clamp as close to the carburetor as possible.
Tighten the clamp securely.
Polyurethane Filter Removal and Service
Kleen Aire® Air Cleaner or TC Type II
1.Remove the cover by pulling outward on the tab (diag.
2-4). On the TC Type II style engine, loosen the two
screws (diag. 2-5).
2.Remove screen A (if equipped), foam filter and screen
B from the air cleaner body (diag. 2-4). On TC Type II
engines, remove the flocked screen and the foam filter
(diag. 2-5).
3. Inspect the flocked screen and foam filter for
discoloration or dirt accumulation. If either condition
is present, service the element or screen using the
following steps.
4.The flockedscreenpre-filtermaybecleanedbyblowing
compressedairthroughthescreen from the backside.
Replace the screen if this procedure does not fully
remove the accumulated particles.
5.Wash the polyurethane filter or polyurethane pre-filter
(usedwith paper airfilters)in adetergentwatersolution
and squeeze (don't twist) until all dirt is removed.
6. Rinse the polyurethane filter or polyurethane pre-filter
thoroughly in clean water. Wrap the filter in a clean
cloth and squeeze (don't twist) until completely dry.
7. Saturate the polyurethane filter with engine oil and
squeeze (don't twist) to distribute and remove excess
oil.
8. Reassemble the filter assemblies per the illustrations.
2-3
Poly Pre-Filter
Air Cleaner
Hose Clamp
Carburetor
Carburetor Adapter
Clamp
2-4
2-5
Screen A Screen B
Lock Nut
Washer
Polyurethane Filter
Air Cleaner
Housing
Poly Air-Cleaner
Flocked Screen
Air Cleaner Cover
Cover Screw
Fuel Tank
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6
CHAPTER 3 CARBURETORS AND FUEL SYSTEMS
Intake Air
Fuel
Engine Vacuum
Impulse
Intake Air
Fuel
Engine Vacuum
Impulse
Intake Air
Fuel
Engine Vacuum
Impulse
3-1
3-2
3-3
GENERAL INFORMATION
TC engines almost exclusively use diaphragm-type carburetors to be able to run effectively at any operating angle. The
diaphragm carburetors are produced by Walbro and Tillotson for Tecumseh. The carburetors use an internal diaphragm
fuel pump to supply the fuel to the carburetor fuel metering chamber. The metering diaphragm has one side exposed to
intake manifold pressure and one side exposed to atmospheric pressure. This diaphragm provides the same basic
function (maintaining the proper fuel level in the carburetor) as the float.
A limited number of TC engines were produced as outboards using a Tecumseh Series II float style carburetor. Consult
the Two Cycle Technician's Handbook (part # 692508) if service is required on this series of carburetor.
When servicing carburetors, use the engine model and specification number to obtain the correct carburetor part number.
An alternate method to find the correct carburetor part number on float type carburetors is to use the manufacturing
number and date code stamped on the carburetor and convert this number to a part number. In the carburetor section
of the Master Parts Manual or Microfiche Catalog, a cross reference chart will convert a carburetor manufacturing
number to a Tecumseh part number.
OPERATION
In the "CHOKE" or "START" position, the choke shutter is
closed, and the only air entering the engine flows through
openings around the choke shutter. As the recoil assembly
is operated to start the engine, downward piston travel
creates a low pressure area in the engine cylinder above
the piston. Higher pressure atmospheric air rushes into
the engine to fill the created low pressure area. Since the
majority of the air passage is blocked by the choke shutter,
a relatively small quantity of air enters the carburetor at
increased speed. The main nozzle and both idle fuel
discharge ports are supplying fuel due to the low air
pressure in the intake of the engine and the fuel side of
the main diaphragm. Atmospheric air pressure on the
opposite side of the main diaphragm forces the diaphragm
upward, depressing the inlet control lever, overcoming inlet
spring pressure and allowing fuel to enter the fuel chamber
through the inlet valve. A maximum fuel flow through the
carburetor orifices combined with the reduced quantity of
air that passes through the carburetor, make a very rich
fuel mixture which is needed to start a cold engine
(diag. 3-1).
At IDLE the throttle shutter is almost closed, the low
pressure acts only on the primary idle fuel discharge port
due to throttle plate position. A relatively small quantity of
fuel is needed to operate the engine (diag. 3-2).
During INTERMEDIATE throttle operation, the secondary
idle fuel discharge port supplies fuel after it is uncovered
by the throttle plate. As the throttle plate opens
progressively further, engine speed increases. The velocity
of air going through the carburetor venturi creates a low
pressure area to develop at the main fuel discharge port
while diminishing the effect of the low pressure area on
the engine side of the throttle plate. When the pressure at
the venturi throat is less than that existing within the fuel
chamber, fuel is forced through the high speed mixture
orifice and out the main fuel discharge port (diag. 3-3).
Idle
Start
Intermediate
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7
At high speed operation, the throttle shutter is in a full
open position. The air velocity through the venturi increases
which further lowers the air pressure at the main fuel
discharge port. All discharge ports are supplying fuel as
the adjustment orifices will allow (diag. 3-4).
The fuel pump diaphragm in the carburetor moves up and
down by pressure changes (pulsations) caused by piston
movement. The pulsations are transferred to the pump by
a passage called the impulse channel. The pump
diaphragm moves up drawing fuel into the pump fuel
chamber during a positive pulse, and a negative pulse
moves the diaphragm down forcing fuel out of the fuel
chamber through the inlet needle into the metering
chamber.
FUEL PRIMERS
Primers used on TC engines supply a solid fuel charge to
the carburetor main nozzle (diag. 3-5). Fuel is forced
directly into the carburetor venturi. A choke shaft and
shutter is not needed or used when a primer is used. This
charge of fuel provides the rich mixture necessary to start
the engine.
Below the main nozzle is a one way check valve to prevent
fuel from being drawn back into the fuel chamber when
the primer bulb is released. The check valve also prevents
air from entering the carburetor during normal engine
operation.
COMPONENTS
Intake Air
Fuel
Engine Vacuum
Impulse
3-4
High Speed
3-5
3-6
1. Diaphragm Cover Screw
2. Metering Diaphragm Cover
3. Diaphragm
4. Diaphragm Gasket
5. Metering Lever
6. Metering Lever Screw
7. Metering Lever Pin
8. Metering Lever Spring
9. Inlet Valve Needle
10. Inlet Valve Seat
11.Welch Plug
12. Choke Shaft
13. Choke Shutter Screw
14. Choke Shutter
15. Idle Mixture Screw
16. Idle Speed Screw
811
17.Throttle Shaft
18.Throttle Shaft Return Spring
19.Throttle Shutter Screw
20.Throttle Shutter
21. Fuel Fitting
22. Fuel Inlet Screen
23. Pump Diaphragm
24. Pump Cover Gasket
25. Pump Cover
26. Pump Cover Screw
27.Tension Spring
28. Dust Seal
29. Dust Seal Washer
12
13
19
20 22
26
27
29
2
1
3
5
17
18
23
24
25
27
28
21
WALBRO CARBURETOR
7
6
10
16
4
14
15
9
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8
TILLOTSON CARBURETOR
1. Diaphragm Cover Screw
2. Metering Diaphragm Cover
3. Diaphragm
4. Diaphragm Gasket
5. Metering Lever
6. Metering Lever Screw
7. Metering Lever Pin
8. Metering Lever Spring
9. Inlet Valve Needle
10. Air Vane
11. Air Vane Screw
12. Dust Seal
13. Dust Seal Washer
14. Dust Seal Retainer
15. Idle Mixture Screw
16. Idle Speed Screw
17.Throttle Shaft
18.Throttle Shaft Return Spring
19.Throttle Shutter Screw
20.Throttle Shutter
21. Fuel Fitting
22. Fuel Inlet Screen
23. Pump Diaphragm
24. Pump Cover Gasket
25. Pump Cover
26. Pump Cover Screw
27.Tension Spring
28. Main Mixture Jet
29.Welch Plug
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Engine Will Not Start
Check For Spark
Check If Spark Plug Is Wet or Dry
See Chapter 6
under "Troubleshooting"
Check Fuel Supply and Fuel Cap
Vent
Restriction in Fuel System
(filter, screen)
Carburetion Problem
Poor Compression
Blockage in Pulse Channel to
Carburetor
Defective Spark Plug
Restricted Air Filter
Improper or Stale Fuel
Carburetion Problems Due to
Flooding, Over Priming, etc.
Ignition System
Plugged Muffler or Exhaust Port
NO
YES
WET DRY
ENGINE TROUBLESHOOTING
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ADJUSTMENTS
Low lll lll l
High lll l l
FUEL SYSTEM
Plugged Tank Filter or Vent l l l l lll
Restricted Fuel Line ll lll
Dirt in Fuel Passage llll ll
Loose, Damaged Fuel Line lll l ll
Leak in Pulse System l l l l lll
Restricted Pulse Channel l l l l lll
Loose Pump Cover Screws l l l lll
Defective Pump Diaphragm lll l lll
AIR SYSTEM
Plugged Air Filter l lllll
Defective Manifold Gasket ll l ll
Loose Carb. Mounting Bolts ll l l
Worn Throttle Shaft or Valve ll
Incorrect Throttle Assembly
Loose Throttle Valve Screw l
Throttle Shaft Too Tight l
Bent Throttle Linkage l
Defective Throttle Spring l
Bent Throttle Stop Lever l
Choke Not Functioning Properly l
Worn Choke Shaft or Valve l l
START
Hard Starting
Fuel Dripping From Carburetor
Floods Engine When Not Running
IDLE (Low Speed)
Will Not Idle
Rich Idle
Idles With Needle Closed
Erratic Idle
"L" Needle Needs Frequent Adjustment
Loads Up While Idling
ACCELERATION & DECELERATION
Will Not Accelerate
Engine Stops When Closing Throttle
Over-rich Acceleration
HIGH SPEED
Will Not Run at W.O.T.
Low Power
No Rich Drop Off
TROUBLESHOOTING CARBURETION -TC SERIES
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METERING SYSTEM
LEVER
Worn Lever l
Set Too High l l ll ll l
Set Too Low llll
Not Free lllll l l
SPRING
Distorted ll
Improperly Installed ll
DIAPHRAGM
Leaking (Air/Fuel) l ll lll
Worn Button l
Improper Assembly l lll
Defective Gasket l l lll
Loose Diaphragm Rivet ll
Hole in Diaphragm l l lll
Loose Cover Screws l l l lll
INLET NEEDLE & SEAT
Foreign Matter l l lll l l l
Binding l l lllll ll l l
Worn Needle Body or Tip ll ll l
NOZZLE CHECK VALVE lll lll
START
Hard Starting
Fuel Dripping From Carburetor
Floods Engine When Not Running
IDLE (Low Speed)
Will Not Idle
Rich Idle
Idles With Needle Closed
Erratic Idle
"L" Needle Needs Frequent Adjustment
Loads Up While Idling
ACCELERATION & DECELERATION
Will Not Accelerate
Engine Stops When Closing Throttle
Over-rich Acceleration
HIGH SPEED
Will Not Run at W.O.T.
Low Power
TROUBLESHOOTING CARBURETION -TC SERIES
(CONTINUED)
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12
TESTING
1. After repeated efforts to start the engine using the procedure listed in the operator's manual fail, check for spark by
removing the high tension lead and removing the spark plug. Install a commercially available spark plug tester and
check for spark. If the spark is bright blue and fires every revolution, proceed to step # 2. If no spark, weak spark, or
intermittent spark see Chapter 6 "Ignition" under "Troubleshooting".
2. Remove the spark plug and visually check the removed spark plug for a wet condition indicating the presence of fuel
mixture in the cylinder.
3. If the spark plug is dry, check for restrictions in the fuel system before the carburetor. If the spark plug is wet,
continue with step # 6. Check the fuel cap vent, the cap must allow air to be blown through it when testing. Using a
proper draining receptacle, remove the fuel line from the carburetor inlet fitting (Type I) or fuel tank (Type II) and pull
off the fuel line. Examine the fuel flow and fuel condition. Improper fuel flow indicates the fuel, fuel line, filter, or tank
require cleaning or replacement.
4. Visually inspect the choke shutter for complete closing or check to see fuel flowing from the main nozzle during
priming. Remove the air cleaner element or air cleaner assembly to provide access for visual inspection.
5. If the fuel flow to the carburetor is adequate and no fuel flows out the main nozzle during priming or choking, the
carburetor will require service. Consult the Troubleshooting Carburetion Chart for possible causes for the lack of
fuel.
6. Check the engine compression using a commercially available compression tester and follow the tester's
recommended procedure. Low compression, no fuel present on the spark plug, adequate fuel flow and a known
good functional carburetor indicates an internal engine problem exists. See Chapter 7 under "Troubleshooting".
SERVICE
CARBURETOR PRE-SET AND ADJUSTMENT
Both the Walbro and the Tillotson carburetors used on TC
engines have non-adjustable main mixture jets. Only the
idle mixture is adjustable by turning the idle mixture screw.
Use the following procedure to pre-set the idle mixture
screw. Turn the idle mixture screw (clockwise) finger tight
to the closed position, then turn the screw counterclockwise
to obtain the proper preset (diag. 3-7).
Walbro model WTA, WT 1 - 1 1/8 turns
Tillotson model HU 1 1/4 - 1 3/8 turns
Final Idle Mixture Adjustment
Start the engine and allow it to reach normal operating
temperature (after 3-5 minutes). As the speed control is
set at the idle position, turn the idle mixture screw slowly
clockwise until the engine R.P.M. just starts to decrease.
Stop and note this screw position. Turn the idle mixture
screw slowly counterclockwise. The engine will increase
R.P.M. Continue to slowly turn the screw until the engine
R.P.M. starts to decrease. Note this position and turn the
mixture screw back clockwise halfway between the two
engine R.P.M. drop off positions. The idle mixture
adjustment is complete.
3-7
Idle Mixture Screw
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13
FUEL TANK SERVICE
TC type II engines have fuel tanks with an integral fuel
screen and integral outlet fuel fitting. Some TC type I engine
models use a pressed in fuel filter or a weighted filter and
a flexible fuel line in the tank. Integral screens or fittings
are not serviceable. Pressed in fuel filters and fittings can
be serviced using the following procedure (diag. 3-8).
1. Press the fuel fitting into the tank and feed the fuel line
in until the filter can be removed through the filler neck.
Remove the filter and fuel line if necessary.
2. To install a new filter and fuel line, push the new fuel
line through the tank outlet until the fuel line protrudes
through the filler neck.
3. On tanks without weighted filters, push a new filter on
the fuel line. For weighted filters, slide the new retaining
ring on the fuel line protruding from the filler neck.
Push the fitting into the line to the fitting shoulder. Slide
the retaining ring over the groove in the fitting and
crimp the retaining ring using a pliers.
4. Attach the fuel line and weighted fuel filter if applicable.
Pull the fuel line through the tank outlet. The filter barb
or the fuel fitting barb must protrude from the tank.
CARBURETOR DISASSEMBLY
1. Note or mark the location and sequence of the
diaphragm(s), gasket(s), and the metering or pump
cover. Remove the screw(s), gaskets, and
diaphragms.
2. Remove the idle mixture screw. On Tillotson model
HU carburetors, remove the plastic screw or brass plug
over the main mixture jet and remove the main mixture
jet if necessary for cleaning (diag. 3-9).
3. Use a 8-32 tap with the tapered flutes removed to turn
into the brass welch plug until it bottoms and begins
to turn the welch plug. Carefully pull the welch plug
from the carburetor body.
4. Note or mark the location and action of the throttle
and air vane, and choke shaft (if applicable). Remove
the screw holding the throttle or choke shutter to the
shaft. Remove the Torx T8 screw (use part # 670334)
holding the air vane to the throttle shaft if applicable.
Remove the clip screw, dust seal retaining clip, and
throttle shaft. On some older Walbro carburetors it is
necessary to remove the circlip on the end of the
throttle shaft to remove the shaft (diag. 3-9).
5. Remove the inlet needle valve, metering lever, and
metering lever spring by removing the retainer screw
on the pivot pin (diag. 3-9).
6. Remove the fuel inlet screen and check valve screen
using an "O" ring pick. Remove all welch plugs using
a sharpened small chisel. Drive the sharpened chisel
into the welch plug, push down on the chisel to pry
the welch plug out of position. Be careful not to damage
the carburetor body (diag. 3-10).
7. On Walbro carburetors, the fuel inlet fitting can be
removed with a pliers using a twisting and pulling
motion. Do not re-use the old fuel fitting. The fuel fitting
on Tillotson carburetors is not replaceable. Do not
remove. Carburetor cleaner will not affect this fitting.
1.
Throttle Shaft
Dust Seal Washer
Metering Lever Screw
3-9
3-10
3-8
3.
2.
4.
Metering Lever Spring
Inlet Valve
Needle
Throttle Shaft Return Spring
Note: Do not allow chisel point to strike
carburetor body or channel reducer
Pierce plug with tip
Welch Plug
Small Chisel
Ò
Ô
Ô
Ô1/8"
Pry out
plug
Metering Lever Pin
Metering Lever
Dust Seal Retainer
Dust Seal
Washer
Dust Seal
Dust Seal
Fuel Inlet
Screen Throttle
Shutter
Screw
Idle Mixture
Screw
Tension Spring
Welch Plug
Main Mixture Jet
Throttle
Shutter
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14
8. Clean all metallic parts in carburetor cleaner. Do not
exceed 30 minutes soak time. Blow out all fuel
passages with compressed air. Do not use tag wire to
clean the orifice in the main mixture seat assembly.
The main mixture seat assembly contains a teflon disc
check valve. If the disc is damaged with tag wire, the
carburetor will not function properly.
CARBURETOR INSPECTION
Visually examine the throttle lever shaft and choke shaft
for wear at the bearing points in the carburetor body.
Inspect the pump and metering diaphragms for hardness,
fuel contamination, holes or tearing in the diaphragm.
Pump diaphragm flapper valves should appear flat with
no curling. Check the inlet screen and check valve screen
for contamination. Check the atmospheric vent hole in the
metering cover and clean if necessary.
Check the inlet needle for wear on the taper portion of the
needle. Replace as necessary.
CARBURETOR ASSEMBLY
1. Install new inlet screen(s) using a small flat punch
slightly smaller than the screen. Push in until the
screen contacts the seat.
2. If removed, install the high speed jet. Use a slightly
larger flat punch to install the brass welch plug over
the high speed jet. The closed, tapered end of the
plug goes toward the jet. Tap the brass welch plug in
until it is flush with the carburetor body. Apply sealant
like fingernail polish to the brass plug.
3. Install new welch plug(s) using a flat punch equal to
or slightly larger than the plug. The welch plug(s)
must be flattened by taps with a small hammer on
the installing punch. Sealant such as fingernail polish
is recommended to apply to an installed welch plug.
Use sparingly and wipe off excess immediately
(diag. 3-11).
4. Install the inlet needle, spring, metering lever and
pin. The metering lever hooks on the inlet needle
and rests on the metering spring. Install as an
assembly and install the retaining screw
(diag. 3-12).
5. Check the metering lever tip height using a metering
lever gauge (part # 670325). The tip height should
be .060" to .070" (1.52 mm to 1.77 mm) from the
face of the carburetor body on Walbro carburetors.
On Tillotson carburetors the tip of the metering lever
should be flush with surface of the carburetor body.
6. Install the idle mixture screw and spring and back
the screw out from the closed position 1 - 1 1/8 turns
for Walbro, 1-1/4 - 1-3/8 turns for Tillotson
carburetors.
7. Install the metering diaphragm, cover gasket, and
cover. Place the cover gasket (over the locator pins
on Walbro only) on the carburetor body, add the
metering diaphragm with the long rivet head toward
the carburetor body on top of the gasket, add the
cover and fasten the four screws (diag. 3-13).
3-11
Flat End
Punch
New Welch
Plug
Note: Punch should be of the
same or larger diameter than
the welch plug.
3-12
3-13
1. Metering Diaphragm Cover
2. Diaphragm
3. Diaphragm Gasket
4. Pump Diaphragm
5. Pump Cover Gasket
6. Pump Cover
6
5
4
3
2
1
Metering Pin
Carburetor Face
Metering Lever Tip
Inlet Needle
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15
8. Install the pump gasket over the locator pins on the
pump cover, add the pump diaphragm next, and
place the assembly on the carburetor body. Check
to see that the locator pins fit the corresponding holes
in the carburetor body. Install the pump cover
retaining screw (diag. 3-13).
9. If removed on Walbro carburetors, install a new fuel
inlet fitting in the same position as the original (diag.
3-14). When installing a new fitting, insert the tip into
the carburetor body, then coat the exposed portion
of the shank with Loctite grade A (red), then press it
in squarely using support on the opposite side to
prevent damage to the carburetor body or fitting.
Press it in until the fitting bottoms out in the carburetor
body.
10. Install the choke and throttle shaft assemblies in the
reverse order of removal. Visually check for proper
operation of the choke and throttle. 3-14
NOTE: Do not re-use old choke or throttle plate shutter screws. New screws are treated with a dry Loctite adhesive
to secure them in place.
11. If applicable, attach the air vane and torque the mounting screw to 3-5 inch pounds (.34 - .57 Nm) (diag. 3-14).
12. Newer style TC series engines use an insulator / spacer between the carburetor and cylinder. That spacer MUST
be installed, as shown, for the fuel pump to operate.
EMISSIONIZED TC CARBURETOR
The Tillotson carburetor is now an emissions grade carb. It has a married idle and high speed circuitry with limited jet
adjustments on the idle.
EMISSIONS CARBURETOR IDLE MIXTURE
ADJUSTMENT PROCEDURES
The carburetor is preset at the factory at a normal setting
required for initial engine operation.
Allow the engine to reach normal operating temperature
(after 3-5 minutes).
Set the engine speed control in the idle position. With the
engine at idle speed (Note: must be less than 2400 R.P.M.
for accurate adjustment). Using a small tip screw driver
that fits through the access hole in the limiter cap, adjust
the mixture screw slowly clockwise until the engine R.P.M.
just starts to decrease. Stop and note this screw position.
Turn the idle mixture screw slowly counterclockwise. As
the engine increases R.P.M. continue to slowly turn the
screw counterclockwise until the engine R.P.M. starts to
decrease. Note this position and turn the mixture screw
back clockwise halfway between the two engine R.P.M.
drop off positions.
Verify the engine will accelerate from low speed to high
speed and that the idle speed remains at the desired
setting.
Once adjustments are complete, center the adjustment
limiter cap between the two stops and press inward to
engage the limiter. The limiter will snap into position and
engage the adjusting screw. All future adjustments should
now be made using the adjusting slot in the limiter cap.
CAUTION: Once the limiter cap is snapped into place it is
not possible to remove the limiter or to adjust the mixture
screw beyond the limits of the limiter assembly. Make sure
that initial adjustments are made per the above procedure
prior to engaging the limiter cap.
3-15
THROUGH HOLE
TOWARD SPARK
PLUG
VACUUM CHANNEL
TOWARDS CYLINDER
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16
CHAPTER 4 GOVERNORS AND LINKAGE
GENERAL INFORMATION
TC series engines are equipped with pneumatic (air vane) governors.The governor's function is to maintain a R.P.M.
setting when engine loads are added or taken away.Air vane governors are controlled by the air velocity created by fins
on the flywheel.Changes in the engine R.P.M.cause the air vane to move.This movement opens the throttle shaft either
by a link between the air vane and the throttle plate, or the air vane is mounted directly onto the throttle shaft.The throttle
is opened as the engine R.P.M. drops and is closed as the engine load is removed.
This chapter includes governor assembly linkage and speed control illustrations to aid in assembly.
OPERATION
Engine R.P.M. changes cause an increase or decrease in
the air velocity created by the fins on the flywheel.The air
velocity exerts pressure on the air vane while a governor
spring exerts pressure against the air velocity force. The
air vane pivots on the engine blower housing base or is
attachedtothe throttle shaft of the carburetor.Asan engine
loadisapplied and the engine's R.P.M drop,the air velocity
also drops, allowing the governor spring to pull open the
throttle shaft and increase engine speed (diag. 4-1).
If the engine uses a remote speed control, the bowden
wire will move the speed control plunger or the throttle
shaft.Movingthe speed control plunger results in changing
the governor spring tension which increases or decreases
the engine's governed speed.
COMPONENTS
TYPE I
1. AIR VANE
2. BACKLASH SPRING
3. GOVERNOR LINK
4. GOVERNOR SPRING
5. MOUNTING SCREW
6. SPEED ADJUSTMENT SCREW
7. SPEED CONTROL BODY
8. SPEED CONTROL LEVER
9. SPEED CONTROL PLUNGER
3.
9.
6.
7.
1.
4.
4.
2.
8.
1.
5.
TYPE II
TYPE II
TYPE I
4-1
4-2
Insert Throttle Link
Spring Hooked
In Notch
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17
TROUBLESHOOTING
ENGINE OVERSPEEDING
1. If the engine runs wide open (faster than normal), shut the engine off or slow it down immediately.
2. Visually inspect the air vane, linkage, carburetor throttle shaft, and speed control for debris blockage, binding,
breakage, or incorrect hook-up. Check the governor spring for a stretched or distorted condition.Remove the recoil
assembly and / or fuel tank if necessary. See "Disassembly Procedure" in Chapter 7.
3. Clean, correct or replace binding or damaged parts. Set the speed control to the recommended engine R.P.M.
ENGINE SURGING
1. Try to stabilize the engine R.P.M. by holding in one position the carburetor throttle shaft on the exterior of the
carburetor.
2.If the engine R.P.M.stabilizes, the governor or governor adjustment should be checked.Follow the procedure under
"Governor Adjustment" in this chapter. If the engine R.P.M. does not stabilize, the engine will require additional
checks see Chapter 3 under ''Troubleshooting".
3.If the problem persists after the governor adjustment, check the engine R.P.M.found on microfiche card # 30 or in the
computer parts lookup. If the setting for high and low speed are within the listed specification and a slight surge is
experienced, increasing the engine idle speed slightly may eliminate this condition.
4. Visually inspect the air vane, linkage, carburetor throttle shaft, and speed control for debris blockage, binding,
breakage, or incorrect hook-up. Check the governor spring for a stretched or distorted condition.Remove the recoil
assembly and/or fuel tank if necessary.See "Disassembly Procedure" in Chapter 7.Repair or replace as necessary.
SERVICE
For governor disassembly or assembly procedures see
"Service" in Chapter 7.
GOVERNOR ADJUSTMENT
Three different styles of governor systems are used on
TC engines. Use the following illustrations (diags. 4-3,
4-4 and 4-5) to identify the governor system used and the
following procedure to adjust the governed engine speed.
1. Allow the engine to run for at least 5 minutes to reach
the operating temperature. Make sure the air filter (if
equipped) is clean and the choke is in the off position.
2.Using aVibratach (part # 670156) or other tachometer,
determine the engine's R.P.M at idle and wide open
throttle.Consult microfiche card # 30 or the computer
parts lookup to obtain the recommended engine
speeds.
3.Using the applicable illustration, either bend the speed
adjustinglever towardthesparkplugendoftheengine
to decrease high speed R.P.M., or bend the lever in
opposite direction to increase R.P.M. On TC Type II
engines,turnthe speed adjustingscrewout toincrease
orin to decrease engine highspeedR.P.M.Ifthespeed
adjustment screw is turned out to increase the engine
R.P.M.,thespeedcontrollevermust be movedtoallow
the speed control plunger to contact the speed
adjustment screw.
4.The low speed is set by moving the throttle control to
the lowest speed position and adjusting the low speed
adjustment screw on the carburetor.
Speed
Adjusting
Lever
Speed
Adjusting
Lever
TYPE I
TYPE I
4-3
Spring Hooked
In Notch
Spring Hooked
In Notch
Decrease Increase
Ý
Ý
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