Hotsy 781SS Service manual

OPERATING INSTRUCTIONS
AND PARTS MANUAL
Thank you for purchasing a Hotsy Pressure Washer. This manual covers the operation and mainte-
nance of your pressure washer. All information in this manual is based on the latest product infor-
mation available at the time of printing. Hotsy, Inc. reserves the right to make changes at any time
without incurring any obligation.
Read instructions carefully before attempting to assemble, install, operate or service this pressure
washer. Failure to comply with instructions could result in personal injury and/or property damage!
MODELS 781SS,
871SS, 921SS
SERIAL NUMBER:
DATE PURCHASED:
FOR SALES AND SERVICE, PLEASE CONTACT:
97-6642
L
I
S
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®

97-6642 • HOTSY 781SS, 871SS, 921SS • REV. 7/06
PRESSURE WASHER Specifications
2
871SS SPECIFICATIONS
 Pump Volume At Pump Head: 2.71 GPM/162.6 GPH
 Pump Pressure At Pump Head: 2400 PSI
 Burner Type: Fuel Oil Fired, 248,500 BTU/Hr.
 Burner Fuel Pressure: 140 PSI
 Machine Power Rating: 7 HP Robin Subaru, Manual Start
 Machine Weight: 291 Lbs.
 Shipping Weight: 330 Lbs.
 Exhaust Stack Size: 8"
 Machine Dimensions: Length=48", Width=27",
Height=42.5"
781SS SPECIFICATIONS
 Pump Volume At Pump Head: 2.5 GPM/150 GPH
 Pump Pressure At Pump Head: 2000 PSI
 Burner Type: Fuel Oil Fired, 248,500 BTU/Hr.
 Burner Fuel Pressure: 140 PSI
 Machine Power Rating: 6 HP Robin Subaru, Manual Start
 Machine Weight: 287 Lbs.
 Shipping Weight: 326 Lbs.
 Exhaust Stack Size: 8"
 Machine Dimensions: Length=48", Width=27",
Height=42.5"
921SS SPECIFICATIONS
 Pump Volume At Pump Head: 3.0 GPM/180 GPH
 Pump Pressure At Pump Head: 3000 PSI
 Burner Type: Fuel Oil Fired, 248,500 BTU/Hr.
 Burner Fuel Pressure: 140 PSI
 Machine Power Rating: 9 HP Robin Subaru, Manual Start
 Machine Weight: 385 Lbs.
 Shipping Weight: 415 Lbs.
 Exhaust Stack Size: 8"
 Machine Dimensions: Length=47", Width=31", Height=49"

3
CONTENTS
97-6642 • HOTSY 781SS, 871SS, 921SS • REV. 7/06
Model Number ______________________________
Serial Number ______________________________
Date of Purchase ___________________________
The model and serial numbers will be found on a decal attached to the
pressure washer. You should record both serial number and date of
purchase and keep in a safe place for future reference.
Introduction & Important Safety Information 4-5
Component Identification 6
Assembly Instructions 7
Installation Instructions 8-9
Operating Instructions 10-11
Storage 11-12
Maintenance 13
Troubleshooting 14-15
Exploded Views 16-17
Exploded View, Parts List 18-19
Burner Assembly & Parts List 20
Control Box Assembly & Parts List 21
Coil Outlet Assembly & Parts List 22
Hose &Spray Gun Assembly & Parts List 23
VBA35 Uloader Exploded View & Parts List 24
Pump Assemblies & Parts Lists 25-27
Pump Exploded Views & Parts Lists 28-31
Wiring Diagram 32
Warranty

97-6642 • HOTSY 781SS, 871SS, 921SS • REV. 7/06
OPERATOR’S MANUAL PRESSURE WASHER
4
INTRODUCTION & IMPORTANT SAFETY INFORMATION
Thank you for purchasing a Hotsy Pressure Washer.
This manual covers the operation and maintenance of
the 781SS, 871SS and 921SS washers. All information
in this manual is based on the latest product information
available at the time of printing.
Hotsy, Inc. reserves the right to make changes at any
time without incurring any obligation.
Owner/User Responsibility:
The owner and/or user must have an understanding of
the manufacturer’s operating instructions and warnings
before using this Hotsy pressure washer.Warning infor-
mation should be emphasized and understood. If the
operator is not fluent in English, the manufacturer’s in-
structions and warnings shall be read to and discussed
with the operator in the operator’s native language by
the purchaser/owner, making sure that the operator
comprehends its contents.
Owner and/or user must study and maintain for future
reference the manufacturers’ instructions.
Owner and/or user must study and maintain
for future reference the manufacturers’ in-
structions.
This manual should be considered a permanent
part of the machine and should remain with it if
machine is resold.
IMPORTANT SAFETY
INFORMATION
WARNING: When using this machine basic pre-
cautions should always be followed, including
the following:
CAUTION:To reduce the risk of
injury, read operating instruc-
tions carefully before using.
1. Read the owner's manual
thoroughly. Failure to follow in-
structions could cause malfunc-
tion and result in death, serious
bodily injury and/or property
damage.
2. Know how to stop the machine and bleed pres-
sures quickly. Be thoroughly familiar with the con-
trols.
3. Stay alert - watch what you are doing.
4. All installations must comply with local codes.
Contact your electrician, plumber, utility company
or the selling distributor for specific details.
WARNING: Flammable liquids
can create fumes which can
ignite causing property dam-
age or severe injury.
5. Risk of explosion - do not
spray flammable liquids or op-
erate in an explosive location.
Operate only where open flame
or torch is permitted.
WARNING: Do not place ma-
chine near flammable objects
when the engine is hot.
WARNING: Keep water spray
away from electrical wiring or
fatal electric shock may result.
Read warning tag on electrical
cord.
WARNING: Spray gun kicks back. Hold with both
hands.
6. Grip cleaning wand securely with both hands be-
fore starting the cleaner. Failure to do this could
result in injury from a whipping wand.
WARNING: Risk of fire. Do not
add fuel when the machine is
operating.
7. Allow engine to cool for 2
minutes before refueling. If any
fuel is spilled, make sure area is
dry before testing spark plug or
starting the engine. (Fire and/or
explosion may occur if this is not
done.)
Gasoline engines on mobile or portable equipment
shall be refueled:
a. Outdoors;
b. With the engine on the equipment stopped;
c. With no source of ignition within 10 feet of the
dispensing point;
d. With an allowance made for expansion of the
fuel should the equipment be exposed to a
higher ambient temperature.
In an overfilling situation, additional precautions are
necessary to ensure that the situation is handled
in a safe manner.
READ OPERATOR’S
MANUAL THOROUGHLY
PRIOR TO USE.
CAUTION
WARNING
WARNING
RISK OF EXPLOSION:
DO NOT SPRAY
FLAMMABLE LIQUIDS.
WARNING
KEEP WATER SPRAY
AWAY FROM
ELECTRICAL WIRING.
WARNING
RISK OF EXPLOSION:
USE CAUTION WHEN
REFUELING.

97-6642 • HOTSY 781SS, 871SS, 921SS • REV. 7/06
5
PRESSURE WASHER OPERATOR’S MANUAL
IMPORTANT SAFETY INFORMATION
WARNING: Risk of injection
or severe injury to persons.
Keep clear of nozzle — Do
not touch or direct discharge
stream at persons. This ma-
chine is to be used only by
trained operators.
CAUTION: Hot discharge flu-
id. Do not touch or direct dis-
charge stream at persons.
8. High pressure developed by these machines can
cause personal injury or equipment damage. Use
caution when operating. Do not direct discharge
stream at people, or severe injury and/or death
may result.
WARNING: High pressure can
cause paint chips or other
particles to become airborne
and fly at high speeds.
9. Eye safety devices and foot
protection must be worn when
using this equipment.
10.Never make adjustments on
machine while in operation.
WARNING: Use only in well
ventilated areas. Failure to
observe this warning could
cause a loss of conscious-
ness or death.
11. Avoid installinginsmallareas
or near exhaust fans. Exhaust
contains poisonous carbon
monoxide gas; exposure may
cause loss of consciousness
and may lead to death. It also contains chemicals
known, in certain quantities, to cause cancer, birth
defects or other reproductive harm.
12. Do not operate with the spray gun in the off position
for extensive periods of time as this may cause
damage to the pump.
13. The best insurance against an accident is pre-
caution and knowledge of the machine.
14. Hotsy will not be liable for any changes made to
our standard machines, or any components not
purchased from Hotsy.
15. Read engine safety instructions provided.
16. Never run pump dry or leave trigger gun closed
longer than 5 minutes.
17. Inlet water must be from a cold, clean fresh city
water supply.
WARNING: Only use recom-
mended fuel. Using other
fuels may result in a serious
explosion causing personal
injury, property damage or
loss of life.
18. Use No. 1 or No. 2 heating oil
(ASTM D306) only. NEVER use
gasoline in your fuel oil tank.Gas-
oline is more combustible than fuel oil and could
result in a serious explosion. NEVER use crank-
case or waste oil in your burner assembly. Fuel unit
malfunction could result from contamination.
19. Do not confuse gasoline and fuel oil tanks. Keep
proper fuel in proper tank.
20. Protect machine from freezing.
21. Be certain all quick coupler fittings are secured
before using pressure washer.
22. Do not allow acids, caustic or abrasive fluids to
pass through the pump.
23. To reduce the risk of injury, close supervision is
necessary when a product is used near children.
Do not allow children to operate the pressure
washer. This machine must be attended dur-
ing operation.
24. Do not operate this product when fatigued or under
the influence of alcohol or drugs. Keep operating
area clear of all persons.
25. Protect high pressure hose from vehicle traffic and
sharp objects.
26. Before disconnecting high pressure hose from
water outlet, turn burner off and pull the trigger
on the spray gun allowing water to cool to below
100° F before stopping machine. Then open the
trigger gun to relieve pressure. Failure to properly
cool down or maintain the heating coil may result
in a steam explosion.
27. Do not overreach or stand on unstable support.
Keep good footing and balance at all times.
28. This machine must be attended during opera-
tion.
WARNING
HIGH PRESSURE
STREAM CAN
PIERCE SKIN AND
TISSUES.
WARNING
RISK OF
ASPHYXIATION.
USE THIS PRODUCT
ONLY IN A WELL
VENTILATED AREA.
WARNING
RISK OF FIRE OR
EXPLOSION: USE
VAPOR FUEL ONLY.
WARNING
USE PROTECTIVE
EYEWEAR WHEN
OPERATING.

97-6642 • HOTSY 781SS, 871SS, 921SS • REV. 7/06
OPERATOR’S MANUAL PRESSURE WASHER
6
COMPONENT IDENTIFICATION
Trigger Gun
Control Box
High
Pressure Hose
Wand
Burner Exhaust
Vent
Coil Drain Plug
Hour
Meter
Engine Fuel Tank
Burner
Pump
Detergent
Inlet Line
Burner
Fuel Tank
High Pressure
Nozzles
Thermostat
Burner Switch
Engine
Pump — Delivers a specific gpm to the high pressure
nozzle which develops pressure.
Spray Gun — Controls the application of water and
detergent onto cleaning surface with trigger device.
Includes safety latch.
Wand — Must be connected to the spray gun.
High Pressure Hose — Connect one end to water
pump high pressure discharge nipple and the other
end to spray gun.
Unloader Valve — Safety device which, when the
spray gun closes, prevents over pressurization.
Unloader

97-6642 • HOTSY 781SS, 871SS, 921SS • REV. 7/06
7
PRESSURE WASHER OPERATOR’S MANUAL
ASSEMBLY INSTRUCTIONS
Unpacking
Unpack carefully. Wear safety glasses or goggles while
unpacking, assembling, or operating pressure washer.
If there are missing components or hidden damage,
immediately contact carrier concerning discrepancies.
1. Cut strapping band from pressure washer and pal-
let.
2. Remove pressure washer from pallet.
Parts Included
•Pressure Washer
•Pressure Hose
•Wand
•Operating Instructions and Parts Manual
•Gasoline Engine Manual
•Parts Bag Containing:
Pressure Nozzles (3 Ea.)
Quick Disconnects (2 Ea.)
Quick Disconnect Plug
Trigger Gun
Tools Required
•8" Adjustable Wrench
•Teflon Tape
•Flat Blade Screwdriver
Pressure Hose, Trigger Gun and Wand
1. When assembling, use teflon tape on all threaded
plumbing connections to prevent leakage.
2. Install the pressure hose on the pressure washer as
shown in Figure 1.
3. Assemble wand components as shown in Figure 2.
NOTE: The pressure nozzle is not to be installed at
this time.
4. Make sure all plumbing connections are tight.
Figure 1 - Pressure Hose Installation
Coil Outlet
Trigger
Gun
Quick
Disconnect
Quick
Disconnect
Wand
Quick Disconnect Plug
Pressure
Hose
Figure 2 - Wand Component Installation
Pressure Hose
Rupture Disk

97-6642 • HOTSY 781SS, 871SS, 921SS • REV. 7/06
OPERATOR’S MANUAL PRESSURE WASHER
8
INSTALLATION INSTRUCTIONS
Getting Started
IMPORTANT: Proper initial installation of equipment
will assure more satisfactory performance, longer
service life, and lower maintenance cost.
IMPORTANT: The use of a backflow preventer on
the water supply hose is recommended and may be
required by local code.
The pressure washer should be run on a level surface
and in a protected area where it is not readily influenced
by outside forces such as strong winds, freezing
temperatures, rain, etc. The pressure washer should
be located to assure easy access for filling of fluids,
adjustments and maintenance. Normal precautions
should be taken by the operator to prevent moisture
from reaching the pressure washer. It is recommended
that a partition be made between the wash area and the
pressure washer to prevent direct spray from the wand
from coming in contact with the pressure washer. Moisture
reaching the equipment will reduce the pressure washer’s
service life. All installations must comply with the local
codes covering such installations.
Venting
DANGER: DO NOT run machine indoors or in an
enclosed area, as exhaust fumes may be hazardous
to your health.
DANGER: DO NOT operate machine in areas where
flammable vapors (gasoline, solvents, etc.) may be
present, as this machine may ignite the vapors.
CAUTION: All venting must be in accordance with ap-
plicable federal and state laws, and local ordinances.
Consult local heating contractors.
If the pressure washer is to be used in an enclosed area, a
flue must be installed to vent burner and engine exhaust to
the outside atmosphere. Be sure the flue is the same size
as the burner exhaust vent on the pressure washer. See
Figure 1 for location. Poor draft will cause the pressure
washer to soot and not operate properly. When selecting
the location for installation, beware of poorly ventilated
locations or areas where exhaust fans may cause an
insufficient supply of oxygen. Proper combustion can
only be obtained when there is a sufficient supply of
oxygen available for the amount of fuel being burned. If it
is necessary to install the machine in a poorly ventilated
area, outside fresh air may have to be piped to the
burner and a fan installed to bring sufficient air into the
machine. Locate the pressure washer so that the flue
will be as straight as possible and protrude through the
roof at a proper height and location to provide adequate
draft. This oil fired pressure washer must have a draft
regulator installed in the flue (available from most heating
contractors). A draft regulator will permit proper upward
flow of exhaust flue gases.
In addition, the pressure washer should never be operated
in an enclosed area where high ambient temperatures
exist. High ambient temperatures (above 100oF) can
cause engine oil failure and will greatly reduce the
engine’s performance.
Gasoline Engine
The gasoline engine is preset for operation at altitudes
below 3000 feet above sea level. If operated at higher
altitudes, it may be necessary to install a high altitude
main jet in the carburetor. Contact an authorized engine
sales and service center for details.
Pre-Operation Check
Pump Oil (SAE 30W non-detergent oil)
 Cold Water Supply (3.5 gpm • 5/8" • 20 psi)
 Hose, wand, nozzles (nozzle size per serial plate)
 Water filter (intact, nonrestrictive)
 Engine fuel (unleaded 86 or higher)
 Engine oil (SAE 10W40)
 Burner fuel (No. 1 or No.2 home heating fuel or die-
sel)

97-6642 • HOTSY 781SS, 871SS, 921SS • REV. 7/06
9
PRESSURE WASHER OPERATOR’S MANUAL
Oil Burner
Burner Air Adjustment: The oil burner on this machine
is preset for operation at altitudes below 3000 feet. If
operated at higher altitudes, it may be necessary to adjust
the air shutter and air band setting. Adjust the air shutter
for a #1 or #2 smoke spot on the Bacharach scale.
To adjust, start machine and turn burner ON. Loosen
two locking screws found in the air shutter openings
and close air shutter until black smoke appears from
burner exhaust vent. Note air shutter position. Next,
slowly open the air shutter until white smoke just starts
to appear. Turn air shutter halfway back to the black
smoke position previously noted. Tighten locking screws.
If the desired position cannot be obtained using only the
air shutter, lock the air shutter in as close a position as
can be obtained, then repeat the above procedure on the
air band setting.
CAUTION: If white smoke appears from burner
exhaust vent during start-up or operation, discontinue
use and readjust air bands.
NOTE: If a flue is installed, have a professional ser-
viceman adjust your burner for a #1 or #2 smoke spot
on the Bacharach scale.
INSTALLATION INSTRUCTIONS
Figure 3 - Burner Adjustment
10
8
6
4
2
Air Shutter Locking Screw
Air Shutter
Air Band
Air Band
Locking Screw
Air Shutter
Locking Screw

97-6642 • HOTSY 781SS, 871SS, 921SS • REV. 7/06
OPERATOR’S MANUAL PRESSURE WASHER
10
OPERATION INSTRUCTIONS
Before Starting
1. Read all manuals provided with this pressure wash-
er. Become familiar with location and function of all
operating and safety controls.
WARNING: Check hoses, fittings, wand, trigger gun
and fuel connections daily for signs of wear, cracks
and looseness, and replace as required.
2. Connect water supply hose to the garden hose con-
nector located on pump. The water faucet and supply
hose must be capable of providing a minimum of 3.5
gallons per minute (GPM).
3. Fill oil burner fuel tank. Use kerosene, #1 grade home
heating oil, #1 or #2 diesel fuel. DO NOT USE GAS-
OLINE, CRANKCASE OIL DRAININGS, ORWASTE
OIL.
WARNING: DO NOT fill engine fuel tank while engine
is running or hot. Let engine cool before refueling or
spontaneous fire may result. Fuel spillage or vapors
could ignite if engine is hot.
4. Fill the engine fuel tank.Do not overfill, fill to the bottom
of filler neck only. Use lead free gasoline minimum 86
octane. DO NOT use gasoline containing more than
15% MTBE, 5% methanol or 10% ethanol. Refer to
the provided gasoline engine manual for additional
details.
5. Check pump and engine oil levels.
6. If detergents are to be used, only use detergents
intended for pressure washers. Follow instructions on
the detergent container.
IMPORTANT: Before installing pressure nozzle on
initial start-up, turn on the water supply and allow
water to run from the end of the wand until clear to
prevent the pressure nozzle from clogging.
IMPORTANT: If the pressure washer has not been
used for an extended period of time, remove the
pressure nozzle from the end of the wand and turn
on water supply. Allow water to run from the end of
the wand until clear.
7. Install the proper pressure nozzle for your cleaning
needs on the end of wand, refer to Figure 4.
IMPORTANT:The trigger gun provided with this pres-
sure washer is equipped with a manual trigger lock to
prevent accidental operation of the trigger gun. (Refer
to Figure 4) The manual trigger lock should be used
whenever the trigger gun is not in use.
To Start
DANGER: DO NOT point wand or trigger gun at your-
self or at any person. Bodily injury may result from
water under high pressure.
WARNING: Wear eye, ear, hand, foot and skin protec-
tion at all times while operating pressure washer.
IMPORTANT: The water must be turned on before
starting. Running the pump dry will cause damage
and void warranty.
IMPORTANT: DO NOT allow the machine to run with
trigger of the trigger gun released for more than
10 minutes at any one time or damage to pump may
occur.
1. Turn ON water supply.
2. Hold wand firmly, release trigger of trigger gun.
3. Place engine ON/OFF switch in the ON position.
4. Open fuel shutoff valve (if so equipped). Move choke
lever to FULL CHOKE position, (choke may not be
needed on warm engine). Move throttle lever to HALF
THROTTLE position.
5. Pull the rope starter slowly until resistance is felt, then
pull briskly. Do not allow the rope starter to snap back
against the engine. Return it gently to prevent damage
to the starter.
6. When the engine starts, move choke lever until
engine runs smoothly. When engine warms, move
choke lever to NO CHOKE position. Move throttle
lever to FULL THROTTLE position.
IMPORTANT: To allow for proper burner operation,
the throttle control must be kept in the full throttle
position during operation.
NOTE: If engine fails to start, refer toTroubleshooting
Guide in this manual.
7. Squeeze trigger of trigger gun and allow air to purge
from system.
8. If HOT water is desired, adjust the thermostat to the
proper temperature and turn burner switch ON. The
burner will light immediately with a small puff of smoke.
You may need to initially adjust your burner for peak
performance. See Oil Burner section under Instal-
lation.If smoke continues, contact Customer Service
at 1-303-792-5200. When the trigger of the trigger
gun is released or when the thermostat temperature
setting is reached, the burner will automatically turn
off.
Figure 4 - Nozzle Installation/Manual Trigger Lock
Manual Trigger Lock
Pressure
Nozzle

97-6642 • HOTSY 781SS, 871SS, 921SS • REV. 7/06
11
PRESSURE WASHER OPERATOR’S MANUAL
To Clean
DANGER: DO NOT place hands or fingers in front of
high pressure spray. Bodily injury may result.
The detergent injector valve operates by reducing the
volume of water, thus a vacuum is achieved and detergent
is drawn into the system. DO NOT reduce the water inlet
flow so the pump cavitates due to water starvation.
Operating a pump with insufficient water will damage
the pump seals.
1. Insert detergent inlet line into container of mixed
detergent.
2. Completely open detergent control knob located
on the side of the detergent injector valve. Refer to
Figure 5.
3. Start the detergent suction by rotating the water
adjustment knob of the detergent injector valve.
Refer to Figure 6.Turning the knob counterclockwise
will pull detergent into the system. The flow may be
observed through the clear detergent line. Secure the
knob position with the knurled nut.
4. The side detergent control knob can now be adjusted
to meter the desired amount of detergent.
5. Wash from the bottom to the top, using side to side
motions.This washes away heavy dirt and allows the
detergent to soak as you work toward the top.
6. Do not wash at a 90oangle to the work (straight at
it). This will allow water to splash back at you and
reduces your cleaning power. Wash at a 30°to 60°
angle to the work. This will allow the water to splash
away from you and the water will wash the dirt away
faster and easier.
7. Use the width of the spray pattern to wash in a
wide path. Overlap spray paths for complete cover-
age washing from side to side, using slow, steady
motions.
8. The nozzle should be 12" to 24" from work, closer for
tough areas. Be careful on painted or delicate sur-
faces, the pressure may damage surface if nozzle is
too close.
9. Small parts should be washed in a basket so the pres-
sure does not push them away. Larger, lightweight
parts should be clamped down so the pressure does
not push them away.
10. Turn the side detergent control knob clockwise (CW)
for detergent decrease. Wait for detergent to clear.
Always rinse with cold water after using detergent.
Rinse from the top to the bottom to prevent detergent
from dripping onto a rinsed area. For the best results,
contact your Hotsy dealer to help you select the best
detergent for your application.
To Stop
1. If detergents were used, draw clear water through the
detergent inlet line to purge detergent. Failure to do
so may clog detergent injector valve.
2. If burner was used, turn OFF burner switch and
allow pump to run cold water through coil for several
minutes.
3. Move throttle lever to idle position.
4. Turn engine ON/OFF switch to the OFF position.
5. Close fuel shutoff valve (if so equipped).
6. Turn water supply OFF.
7. Squeeze trigger of trigger gun to relieve system
pressure.
STORAGE
DANGER: DO NOT store flammable liquids (gasoline,
diesel fuel, solvents, etc.) near pressure washer, or in
non-ventilated areas.
Protect from freezing by storing in a heated area, or by
flushing the system with antifreeze (use an automotive
engine antifreeze or windshield washer solvent to
antifreeze). To flush the system with antifreeze, the
following steps are to be followed:
1. Connect the water supply hose to the garden
hose connector located on the pump. Turn on water
supply.
2. Place the detergent inlet line into a container of
antifreeze.
3. Hold wand firmly, release trigger of trigger gun.
4. Start engine. Place throttle lever in Full Throttle
position.
5. Squeeze trigger of trigger gun and allow water to
flow from the end of the wand. Watch for antifreeze
to be drawn through the detergent inlet line. Allow
the antifreeze to be drawn into the system for 5 to
10 seconds.
6. Release trigger of the trigger gun and stop engine.
7. Turn off water supply and disconnect water supply
hose from the pump.
OPERATION INSTRUCTIONS
Figure 5 - Detergent Injector Valve
Detergent Control Knob
Detergent
On
Water Adjustment Knob
Detergent
Off
Water
Increase
Water
Decrease

97-6642 • HOTSY 781SS, 871SS, 921SS • REV. 7/06
OPERATOR’S MANUAL PRESSURE WASHER
12
8. Attach a short length of hose (approximately 3 feet
long) to the garden hose connector located on the
pump. Install a funnel in the other end of the hose as
shown in Figure 6.
9. Hold wand firmly, release the trigger of the trigger
gun.
10. Start engine. Place throttle lever in the idle position.
11. Squeeze trigger on trigger gun.
12. Slowly pour antifreeze into the funnel. Continue to
add antifreeze until antifreeze flows from the end of
the wand.
13. Squeeze and release the trigger of the trigger gun
several times to antifreeze the unloader system.
14. Release the trigger of the trigger gun. Stop engine.
15. Squeeze the trigger of the trigger gun to relieve system
pressure.
For added protection, after antifreezing, disconnect the
pressure hose from the machine and remove the coil drain
plug. After coil has drained, replace pressure hose and
coil drain plug. If the pressure washer is not to be used
for an extended length of time, it is recommended that
the system be flushed with antifreeze for rust protection.
Refer to the Gasoline Engine Manual for engine storage
information.
OPERATION INSTRUCTIONS
Garden Hose
Connector
Figure 6 - Winterizing
Funnel

97-6642 • HOTSY 781SS, 871SS, 921SS • REV. 7/06
13
PRESSURE WASHER OPERATOR’S MANUAL
MAINTENANCE
WARNING: Unauthorized machine modification or
use of non-approved replacement parts may cause
personal injury and/or property damage and will void
the manufacturer warranty.
Pump
Lubrication: To lubricate pump, use 30W non-detergent
oil for pump crankcase. Crankcase must be filled to center
of red dot on oil gauge found on the end of the pump, refer
to Figure 7. During the break-in-period, make sure the
oil is changed after the first 40 hours of operation. After
that, replace oil every 3 months or 500 hours of operation,
whichever comes first.
Proper Pump Care:
DO NOT pump acids.
DO NOT allow pump to run dry.
Winterize if storing in freezing temperatures, refer
to Storage for details.
Use a water softener on the water system if known
to be high in mineral content.
Use only high quality detergents and follow manu-
facturer's mix recommendations.
Flush the system with clear water immediately
after using detergent solutions.
Clean filter screen on detergent inlet line
periodically.
Flush the pressure washer system with antifreeze
if storing for an extended period of time, refer to
Storage for details.
Gasoline Engine
Refer to the provided Gasoline Engine Manual for
recommended maintenance.
Relief Valve
WARNING: The relief valve on this pressure washer
has been factory set and sealed and is a field nonad-
justable part.Tampering with the factory setting may
cause personal injury and/or property damage, and
will void the manufacturer warranty.
Unloader Valve
WARNING: The unloader valve on this pressure
washer has been factory set and sealed and is a field
nonadjustable part.Tampering with the factory setting
may cause personal injury and/or property damage,
and will void the manufacturer warranty.
Burner Fuel Filter
Drain any water which has accumulated in fuel filter
and clean or replace filter element as needed.
Heating Coil
Coil Descaling: In hard water areas, scale buildup within
the heating coil will occur. Scale deposits will decrease
the water temperature rise and may eventually clog the
heating coil. Contact your local service center when
descaling is needed.
Coil Desooting: Poor grades of fuel oil or inadequate
combustion air will cause heavy soot buildup on the
outside surface of the heating coil. These deposits will
insulate the coil. This will restrict the air flow through the
coil, further aggravating the soot buildup. Contact your
local service center when desooting is needed.
Hour Meter
This hour meter will monitor the total hours of operation of
the pressure washer to signal when routine maintenance
is required.
Figure 7 - Pump Lubrication
Oil Fill/Dipstick
Oil Drain Plug
Oil Gauge

97-6642 • HOTSY 781SS, 871SS, 921SS • REV. 7/06
PRESSURE WASHER Troubleshooting Guide
14
TROUBLESHOOTING
SYMPTOM POSSIBLE CAUSES CORRECTIVE ACTION
GAS ENGINE WILL
NOT RUN.
Out of gas Replenish supply. Use only recom-mended
fuels. Refer to Before Starting under Op-
eration.
Fuel valve closed (if so equipped) Open valve.
Loose spark plug wire Reconnect.
Choke or throttle set incorrectly Refer to To Start under Operation.
Engine ON/OFF switch in OFF position Place engine ON/OFF switch in ON position.
Low engine oil level. Replenish supply. Engine will not start or run
if oil is low (on engines equipped with low oil
protection).
Refer to provided gasoline engine manual for additional troubleshooting
PRESSURE
WASHER RUNS
BUT WON'T
SPRAY.
Trigger of trigger gun released Squeeze trigger.
Water supply not turned on Open water supply valve.
Clogged pressure nozzle Clean pressure nozzle opening.
If water spray doesn't show with in 10-15 seconds discontinue running the
machine and troubleshoot as damage to the pump will occur if allowed to run
LOW SPRAY
PRESSURE AT
PRESSURE
NOZZLE.
Inadequate water supply. Fully open faucet. Check for kinked or dam-
aged hose. Use 3/4 inch minimum hose.
Check for debris clogging inlet screen.
Partially clogged or damaged pressure
nozzle
Clean or replace.
Air being drawn through detergent inlet
line
Refill detergent container. Ensure that pick-
up screen is fully immersed.
Detergent injector valve not set cor-
rectly
Refer to To Clean for settings.
UNEVEN SPRAY
PATTERN.
Partially clogged or damaged pressure
nozzle.
Clean or replace.
PRESSURE
WASHER WILL
NOT PRODUCE
HOT WATER.
Burner switch in OFF position. Place switch in ON position.
Inadequate fuel supply Refill fuel tank. Use only recommend-ed fu-
els. Refer to Before Starting under Opera-
tion.
Inadequate water supply Fully open faucet. Check for kinked or dam-
aged hose. Use 3/4 inch minimum hose.
Check for debris clogging inlet screen.
Trigger of trigger gun released Squeeze trigger. Water must be spraying for
burner to light

97-6642 • HOTSY 781SS, 871SS, 921SS • REV. 7/06
15
PRESSURE WASHER Troubleshooting Guide
TROUBLESHOOTING
When ordering from your dealer, please provide the following:
Model Number: 781SS, 871SS, 921SS
Machine Serial Number: ________________________________
Component Part Number: ______________________________
Description: __________________________________________
IMPORTANT
If the pressure washer demonstrates other symptoms or the corrective actions
listed do not correct the problem, contact the local authorized Hotsy Service
Center. The Hotsy Service Center can be identified by visiting www.hotsy.com or
by calling 1-800-525-1976.
SYMPTOM POSSIBLE CAUSES CORRECTIVE ACTION
PRESSURE WASHER
WILL NOT PRODUCE
HOT WATER
...continued
Thermostat set too low. Adjust thermostat to desired temperature.
Blown fuse Replace. Fuse is located in Control Box.
Engine is running too slow Move throttle lever to full throttle position.
POOR OR NO
DETERGENT FLOW.
Inadequate detergent supply. Refill detergent container. Ensure that pick-
up screen is fully immersed. Open detergent
valve.
Detergent screen or hose
clogged
Clean. Always start with a clean deter-gent
container.
Detergent injector valve not set
correctly
Refer to To Clean for settings.
Clogged detergent injector
check valve
Clean check valve at detergent injector inlet.
POOR CLEANING. Improper detergent concentra-
tion or mixing.
Mix detergent per manufacturer's instructions.
Ensure that powdered detergents are fully
dissolved.
Wrong detergent for the
application
Select appropriate detergent
Rinsing with hot water A final rinse with cold water will reduce water
spotting

97-6642 • HOTSY 781SS, 871SS, 921SS • REV. 7/06
OPERATOR’S MANUAL PRESSURE WASHER
16
EXPLODED VIEW - LEFT SIDE
19
9,14
15
16
1813
12
24
23
53
11
27
7
8
26
25
6
5
2
1
6
5
10
22
21
20
44
6
5
54
For
Detail See
Coil Outlet
Assy
For
Detail See
Control Box
Illus.
For Detail
See Burner
Illus.
Rectifier
(Reversed
View)

97-6642 • HOTSY 781SS, 871SS, 921SS • REV. 7/06
17
PRESSURE WASHER OPERATOR’S MANUAL
EXPLODED VIEW - RIGHT SIDE
43
33
31
46
45
6
50
49
47
48
41
51 52
40
30
32
33
31
29
28
36, 37
35
34
39
32
38
31
32
4
32
31
42
3
5
6
For
Detail See
Pump Assy
Illus.
55

97-6642 • HOTSY 781SS, 871SS, 921SS • REV. 7/06
OPERATOR’S MANUAL PRESSURE WASHER
18
EXPLODED VIEW - PARTS LIST
ITEM PART NO. DESCRIPTION QTY
1 318226 Chassis, Welded Assy 1
375575 Chassis, Weldment (921SS) 1
2 780460 Washer, 5/16" x 1-1/4", Fender, SAE 3
3 952724 Tank, Fuel, 6-Gallon 1
952733 Tank, Fuel, 8 Gal Hotsy (921SS) 1
4 707116 Hose, 1/4", Fuel Line, Green 22"
5 703155 Nut, 5/16", SMAEC, NC (781SS, 871SS) 17
(921SS) 15
6 780452 Washer, 5/16", Flat, SAE (781SS, 871SS) 14
780562 Washer, 3/18", Flat, SAE (921SS) 10
7 859815 Grommet, Rubber, Nozzle Holder 3
8 646113 Label, Detergent Metering 1
9 799484 Nut, 10/32" Keps 4
10 2-010531 Mount Rubber Vibration, 5/16", 70 Duro (781SS, 9871SS) 4
2-010532 Mount Rubber Vibration, 3/8", 70 Dura (921SS) 4
11 834416 Label, Instructions 1
12 860273 Regulator, Voltage, 15 Volt 1
13 357054 Hose, 3/8" Push-on 30"
14 735323 Screw, 10/32" x 3/4" BH SOC CS 4
15 268006 Insulation, Cerafelt 18" x 50" 1
16 226222 Coil, 16" 1
17 780480 Washer, 3/8", Lock Split Ring (921SS) 4
18 375449 Coil, Tank SS, Weldment 1
19 824115 Clip, Retaining, U-Type 4
20 213044 Top Hat, Weld Assy, 16" Hotsy Coil 1
21 268004 Insulation, Cerafelt, 16 OD x 8.3 ID 1
22 860102 Ring, Insulation Retainer, 16" Top Hat 1
23 829979 Label, Plate Aluminum 2
24 10-07993 Label, Warnings 1
25 859806 Grommet, 2-1/8" x 2-7/8" x 7/16" Rubber 1
26 815329 Bushing, 1" Snap 1
27 616000 Bushing, Snap, 5/8" 1
28 698200 Nipple, 1/4" x 2" x 1/2", Brass 1
29 615279 Bushing, 3/8" x 1/4", Galv. 1
30 851080 Filter, Fuel Hotsy, 3/8" Female 1
31 698020 Hose Barb, 1/4" Barb x 1/4" ML Pipe 3
32 823988 Clamp, Hose, UNI .46-.54 ST 4
33 867368 Hose, 1/4", Push-On, Fuel Line 1
34 780456 Washer, 5/8", Flat, SAE 8
35 983013 Wheel & Tire, 6.5" Steel Rim, 12.5" Tire 4
36 817322 Cap, 5/8" Axle Hub, Black 4
37 848616 Nut, .61 ID, Push, Flat 4
38 817312 Cap, w/Fuel Gauge 1
39 661277 Standpipe 1
40 754711 Tee, 3/8" Female 1

97-6642 • HOTSY 781SS, 871SS, 921SS • REV. 7/06
19
PRESSURE WASHER OPERATOR’S MANUAL
EXPLODED VIEW - PARTS LIST
ITEM PART NO. DESCRIPTION QTY
41 799490 Swivel, 1/4" JIC Fem, Push-On 1
42 815230 Bushing, Rubber, Nitrile 2
43 2-10491 Plug, 1/4" JIC 1
44 213191 Insulation 1
45 615433 Bolt, 5/16" - 24 x 3/4" NF HH 4
46 860282 Reducer, M14 to 1/4" F 1
47 646226 Label, Hot/Caliente w/Arrows Warning 1
48 661278 Engine, 7 HP Robin (871SS) 1
661280 Engine, 6HP Robin (781SS) 1
5-0005 Engine, Robin 9HP (921SS) 1
49 615939 Screw, 5/16" x 1-1/2" Whiz (781SS, 871SS) 2
612985 Bolt, 3/8" x 1-1/2", NC HH (921SS) 4
50 262208 Hose, 3/8" x 22", 1 Wire, Pressure Loop (871SS) 1
4-02047722 Hose, 3/8" x 22" 2-Wire (781SS, 921SS) 1
51 801102 Nipple, 3/8" Hex, Steel 1
52 715744 Plug, 3/8", Sq. Head, Galv. 1
53 926598 Rivet, 1/8" x 1/4", POP, AL 8
54 90-10127 Bolt, 5/16" x 2-3/4" Whiz Loc (781SS, 871SS) 2
444461 Label, Caution, Gasoline, White 1
646026 Label, Warning, Carbon Monoxide 1
834153 Label, Fuel Type 1
834154 Label, Caution Winterize 1
834159 Label, Use Hotsy Detergent 1
646095 Label, Troubleshooting 1
213191 Insulation Pancake, 18" 1
753187 Key, 3/16" x 3/16" x 2" SST 1
890874 Tag, Oil Burner 1
735321 Screw, 4 mm x 6 mm, Pan Head 1
890873 Tab, Gas Engine 1
890769 Warning, Unloader 1
9.800-018.0 Label, Tip Over 1
9.800-049.0 Label, Cleaning Solution 1
55 799515 Nipple, 1/2" JIC x 3/8" Pipe (781SS, 921SS) 1
Not Shown

97-6642 • HOTSY 781SS, 871SS, 921SS • REV. 7/06
OPERATOR’S MANUAL PRESSURE WASHER
20
BURNER ASSEMBLY
ITEM PART NO. DESCRIPTION QTY
1 616027 Burner 1
2 698023 Nipple 3/8" x 1/4" Hose 1
3 851080 Fuel Filter 1
4 615279 Reducer Bushing 3/8" x 1/4" 1
5 698200 Pipe Nipple 1/4" x 2-1/2" 1
6 823988 Clamp 2
7 698019 Nipple 1/8" x 1/4" Hose 1
8 900650 Nozzle, 1.50, 90° 1
9 REPLACEMENT PARTS
875490 Filter Element 1
723369 Solenoid 1
661413 Electrodes 1
830492 Fuel Pump 1
676894 Fuel Line 1
783813 Motor 1
630730 Coupling 1
676640 Blower Fan 1
Not Shown
Electrode Settings
BURNER ASSEMBLY PARTS LIST
6
1/8"
Air Cone
8
5/16" 3/16"
1/4"
2
6
1
5
4
3
7
Nozzle
Electrodes (2)
To Fuel Tank
To Fuel Tank