Kärcher KMR 1250 B User manual

5.905-262
09.02
KMR 1250
(KMR 1250 B, KMR 1250 LPG, KMR 1250 D)
1.091- . . .
Service Manual
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5.905-122
4-Stroke Internal
Combustion Engines
Service-Manual
5.905-122

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Foreword KMR 1250 B, LPG, D
Foreword
Good servicing requires extensive and relevant training as well as comprehensible reference
documents.
We therefore offer basic and advanced training courses for the full range of our products to all
service technicians on a regular basis.
In addition, we produce service manuals for the major units in our product line. While these are
ideal for initial use as instruction manuals, they are designed to serve as an essential reference
in the future.
To augment our product-related communications, we regularly distribute service information
bulletins providing details about ongoing product development.
Copyright Notice
Copyright 2002 by Alfred Kärcher GmbH & Co. All rights reserved. No part of this publication may
be reproduced, stored in a retrieval system, or transmitted in any form or by any means, i.e.,
electronic, mechanical, photocopying, recording or otherwise, without the written permission of
Alfred Kärcher GmbH & Co.
ALFRED KÄRCHER GmbH & Co.
Customer Service Training
P.O.Box160
71349 Winnenden, Germany
http://www.karcher.de

3
KMR 1250 B, LPG, D Table of Contents
Contents
Unit functions ...........................................................................................................4-15
Overview ............................................................................................................................... 4-5
View from front ..........................................................................................................................6
Controls.....................................................................................................................................7
GasolineEngine(HONDA GX270)........................................................................................ 8-9
LP Gas Engine (HONDA GX 270).......................................................................................10-11
DieselEngine(YANMARL 70AE-DE) ............................................................................... 12-13
Steering and Drive Power........................................................................................................14
Sweeping system....................................................................................................................15
Troubleshooting Information...................................................................................4-15
Starter Fails to Turn Engine ............................................................................................... 16-18
Starter Turns Engine but Engine Fails to Start................................................................... 19-20
Engine Runs but Machine Fails to Move............................................................................ 21-25
Maintenance Procedures (gasoline and LPG engine) ....................................................... 26-27
Maintenance Procedures (LPG engine) ............................................................................ 28-29
Maintenance Procedures (diesel engine) .......................................................................... 30-31
Parking Brake – No Function ...................................................................................................32
Brush Roller – Poor Performance ..................................................................................... 33-34
Brush Roller – No Rotation......................................................................................................35
Side Brushes – Poor Sweeping Performance.........................................................................36
Excessive Unit Dusting...................................................................................................... 37-41
Filter cleaning Motor – No Function .........................................................................................42
Hydraulic Unit – No Function ...................................................................................................43
Debris Container – Very SlowAscent ......................................................................................44
Debris Container – No FullAscent...........................................................................................45
Excessive Steering Free Play..................................................................................................46
Hydraulic Block Diagram .......................................................................................48-49
Electrical Circuit Diagram ......................................................................................50-55
Maintenance Procedures for B, LPG & D Models ................................................56-57
Technical Specifications........................................................................................58-59
SpecialTools...........................................................................................................60-62
Index ........................................................................................................................63-65

4
Unit Functions KMR 1250 B, LPG, D
Drive system
– When the hood is lifted up toward the rear, all
components become accessible for mainte-
nance purposes.
– Hydrostatictransmissionwithmechanicalfree-
wheeling device provides variable control of
forward and reverse driving speeds.
– Parking brake lever actuates transmission-
mounted disc brake.
– Nofootbrakerequired.Transmissionprovides
braking effect.
– Transmission, impeller fan, brush roller and
side brushes are belt-driven.
– Rear wheels are chain-driven.
– To start engine, driver must occupy operator
seat (seat contact switch).
– Discharge of debris container via electrically
driven hydraulic unit.
Sweeping system
– Brush roller counter-rotates against direction
of unit motion (throw-over principle).
– Debris container is located at rear of brush
roller.
– Two-position adjustment of brush roller via
control lever:
Centerposition:Rigidbrushrollersuspension
for level surfaces.
Bottomposition:Floatingbrushrollersuspen-
sion for uneven surfaces.
– Quick-change brush roller replacement. No
tools required.
– Side brush automatically extends outward
when lowered.
– Coarse-dirtflapaccommodatespickupofbev-
erage cans, etc.
– Hydraulic discharge of debris container in
raised position (two-hand operation).
Suction and filtering system
– Dust pickup at brush roller.
– Large-capacitydustfilterwithmechanicaldust
removal.
– Each time engine is shut off, dust filter is sub-
jected to automatic cleaning cycle of approx.
15-second duration.
– Impeller fan with closeable exhaust-air hatch
for wet-sweeping operation.
– Quick-changedustfilterreplacement.Notools
required.
– Impeller fan driven by elastic belt. No tension
adjustment required.

5
KMR 1250 B, LPG, D Unit Functions
Engine KMR 1250 B
– Single-cylinder, air-cooled gasoline engine
(HONDA GX 270) w/ electric starter. Uses
standard grade unleaded gasoline.
– Engine features oil level sensor.
Engine 1250 LPG
With the exception of the conversion to run on
liquefied petroleum gas (LPG), the unit is iden-
tical to the basic KMR 1250 B version.
– ThegasolineengineisthesameasintheKMR
1250 B (HONDA GX 270).
– The LP gas cylinder is mounted behind the
driver’s seat. As the gasoline tank is discon-
nected, its use is strictly prohibited.
– Thecarburetor has been converted toLP gas
operation.
– The engine compartment accommodates an
additionalgas regulator requiredto adjust the
air/fuel mixture for the engine.
– Themechanicalchokehasbeenconvertedto
electrical control; it acts upon the gas regula-
tor.
Engine 1250 D
With the exception of the different engine type,
the unit is identical to the basic KMR 1250 B
version.
– Single-cylinder,air-cooleddieselengine(YAN-
MAR L 70 AE-DE) w/ electric starter.
– Features compression release for short-term
operation to help overcome top dead center
when starting the engine.

6
Unit Functions KMR 1250 B, LPG, D
View from front
1 Gas cylinder (LP Gas)
2 Steering wheel
3 Driver seat
4 Lifting mechanism for debris container
5 Rear wheel, chain-driven
6 Fuel tank for KMR B / D
7 Engine KMR B / LPG / D
8 LH side brush (option)
9 Front wheel
10 Headlights
11 RH side brush
12 Controls (see page 7)
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KMR 1250 B, LPG, D Unit Functions
1 Lever dust pickup, Close / Open
2 Button clean dust filter (S2)
3 Button lower debris container (S6)*
4 Button raise debris container (S8)*
5 Button tilt debris container (S7)*
6 Leverparkingbrake
7 Lever coarse-dirt flap
8 Headlight switch (S4)
9 Operating hours counter
10 Button two-hand operation, hydraulic (S5)
11 Lever LH side brush, Raise / Lower
(option)
12 Lever brush roller, Raise / Lower
(suspension: rigid or floating)
13 Lever RH side brush, Raise / Lower
14 Throttle lever
15 Button horn (S10)
16 Ignition switch (S1)
17 Choke
18 Drive pedal
ORIGINAL
and
REVISED
* Function available only in conjunction
with two-hand operation button (10).
( ) See circuit diagram.
Controls
11 12 13 14 16 17 16
10
9
8
7
6
5
4
3
2
1
15
14
15
1818
16
15
14
17

8
Unit Functions KMR 1250 B
Gasoline Engine (HONDA GX 270)
1 Stop screw, throttle valve
2 Idlejet
3 Bypass
4 Throttlevalve
5 Idleorifice
6 Idle jet bore and idle air channel
7 Carburetor throat (venturi)
8 Idleairinlet
9 Chokevalve
10 Mainairjet
11 Idle system
12 Emulsion tube
13 Airorifice
14 Float chamber
15 Mainjet
16 Adjusting screw, idle mixture
17 Fuelinlet
18 Inlet,floatvalve
19 Float
20 Float valve w/ float needle
21 Float
21 20 1819 17 5 15 14
13
12
9
10
7
8
642
1
16
33
3
11
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KMR 1250 B Unit Functions
Gasoline Engine (HONDA GX 270)
Float system
When float chamber (14) is empty, fuel passes
fromfueltankintofloatchamber(14)viathefloat
valve inlet (18). The rising fuel level causes the
float (21) to be raised.
The inflow of fuel is interrupted when the float
(21)causesthefloatvalvetoclose.Drawingfuel
forengineoperationfromthefloatchamber(14)
causesthefloat(21)tobelowered,whichinturn
opens the float valve (18).
Thiscyclicalprocedureensuresaconstantlevel
of fuel inside the float chamber (14).
Float chamber equalization
On the carburetor side, the airspace inside the
float housing is connected with the outside at-
mosphere by means of a channel. This facili-
tates the equalization of the pressure equilibri-
um inside the float chamber as the fuel level ris-
es or falls.
Idling operation
Whentheengineisidling,thethrottlevalve(4)is
fully closed.
– This causes negative pressure to occur be-
tween the throttle (4) and the crown of the
engine piston, with the latter moving toward
bottom dead center while the intake valve is
open.
– The atmospheric pressure inside the float
chamber (14) then causes fuel to be con-
veyed through the main jet (15) and idle jet
(2).
– Theidlejet(2)controlstheflowoffuelthrough
the idle bypass channel (3). The fuel then
blends with the air being drawn in through
the idle air channel (6).
– The resulting air/fuel mixture then flows into
the engine.
– The idle mixture adjusting screw (16) con-
trols the volume of air/fuel mixture that is al-
lowed to flow through the idle orifice (5).
Partial load operation
Engine speed rises when the throttle valve (4)
opens, and the volume of the air/fuel mixture
being drawn through the idle jet (2) increases.
Full load operation
Infullloadoperation,thethrottleiswide(4)open:
– Air flows through the carburetor throat, or
venturi(7).Becausethediameteroftheven-
turi outlet is smaller than that of the intake,
the air is accelerated as it passes through.
This increased flow velocity causes nega-
tivepressuretooccurattheoutletsideofthe
main jet (15).
– Pressure inside the float chamber (14) is
equalizedviaanatmosphericreliefchannel.
Becauseatmosphericpressureishigherthan
thepressureinthecarburetorthroat(7),fuel
is transported from the float chamber (14),
and pressed through the main jet (15) into
the emulsion tube (12).
– The air flowing through the main air jet (10)
isblendedwiththefuelthatisflowingthrough
the orifices of the emulsion tube (12).
– This mixture is then drawn into the carbure-
tor throat (7), where it is enriched with more
air before passing into the engine.
Choke system function
Thechokevalve(9)shouldbeclosedonlywhen
startingacoldengine.Thiscausesthefollowing
to happen:
– Theclosedchoke valve (9)allows less airto
be drawn into the carburetor throat (7).
– However, the fuel volume being drawn in
through the main jet (15) remains the same.
– This causes the fuel component in the air/
fuel mixture to rise, with the richer mixture
providing easier engine starting.
Note:
For information on other maintenance and
adjustmentsoftheengine,refertotheServ-
ice manual „4-Stroke Internal Combustion
Engines“ (5.905-122).

10
Unit Functions KMR 1250 B, LPG, D
1 Valve guard
2 LP gas line
3 Cylinder shutoff valve
4 Outlet tube
5 LP gas cylinder
6 Sun shield
7 LP gas in gaseous state
8 LP gas in liquid state
9 Carburetor
10 Engine
11 Vacuum line
12 LP gas line
13 Gas filter
14 Solenoid valve, gas supply
15 Mixture control screw (MIN eng. speed)
16 Gas regulator
17 Choke lifting solenoid
18 Mixture control screw (MAX eng. speed)
LP Gas Engine (HONDA GX 270)
11
14
8
17
16
18
9
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15 1314 12 11 12
16
15
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11
KMR 1250 B, LPG, D Unit Functions
– ThepresenceoffrostonanypartoftheLPgas
system indicates a possible leak. Close the
cylinder shutoff valve (3) immediately. Apply
suitable leak detection medium (soapy water
or Leak Detecting Spray 6.282-033) to gas
lines, solenoid valve, gas regulator and gas
hosetocarburetor.Opencylindershutoffvalve
(3), and check for formation of bubbles. The
unitmaybereturnedtoserviceonlyafterthor-
ough repairs have been carried out by ap-
proved specialists.
Note:
The LP gas system of the unit must be in-
spected by a licensed expert in 6-month
intervals.Theresultsofeachinspectionmust
be made available in the form of a test cer-
tificate.
– Anexpertisdeemedtobeapersonwho,based
on his professional education and skills, pos-
sessessufficientknowledgeof,andexpertise
in, the field of LP gas systems, and who is
sufficiently familiar with applicable working
directivesandaccidentpreventionregulations,
as well as commonly accepted procedures of
this technology, all of the above enabling him
to evaluate, determine and assess the safe
operational state of LP gas systems.
Gas system
– Opening the shutoff valve (3) on the LP gas
cylinder(5)causesgastoflowthroughthegas
filter(13).Atthispoint,possiblecontaminants
are trapped in a paper filter, and metallic par-
ticlesfromgascylinderareremovedbymeans
of a small magnet.
– Setting ignition key to Pos. 1 (ON) opens so-
lenoidvalve(14),allowingLPgastoflowfrom
gasfilter(13)intoprimarychamberofgasreg-
ulator(16).Here,aspring-loadedvalvereduc-
es gas pressure to approximately 150 mbar
(2.2 psi).
– When starter begins to crank engine (10), a
vacuum is created in the suction channel.
Through vacuum line (11), this vacuum acts
onlow-pressurediaphragminsecondarystage
of gas regulator. Diaphragm opens low-pres-
surevalve,andgascanbedrawnintoengine.
– Pressing choke button causes choke lifting
solenoid (17) to open low-pressure valve, al-
lowing gas to flow directly through carburetor
and into engine. This function is particularly
important in cold-starting situations. To pre-
vent high-level enrichment of intake mixture
with LP gas, choke button should not be
pressed for longer than 3-5 seconds.
Note:
Theconnectiononcylindershutoffvalve(3)
must face straight up (extraction of LP gas
in gaseous state).
LP Gas Engine (HONDA GX 270)
Carburetor in LP gas operation (example)
1 Gas inlet
2 Air intake
3 Air/fuel mixture outlet
4 Mixing chamber
5 Gas jet
Gas regulator
– Engines using LP gas as a fuel are equipped
withagasregulatorwhichfeedsLPgastothe
carburetorof a gasolineengine. The carbure-
torgeneratesanair/fuelmixturewhichisdrawn
into the combustion chamber for ignition.
Note:
For information on other maintanance and
adjustmentsoftheengine,refertotheServ-
ice manual “4-Stroke Internal Combustion
Engines” (5.905-122).

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Unit Functions KMR 1250 B, LPG, D
Diesel Engine (YANMAR L 70 AE-DE)
1 Drive shaft
2 Housing, engine
3 Piston
4 Cylinder head
5 Injector
6 Fuel feed line
7 Fuel line from fuel tank
8 Injection pump
9 Shim
10 Housing, injection pump
11 Cam shaft
Injection system
The injection pump (8) delivers fuel to the injec-
tor nozzle (5) via fuel line (6). The fuel, is then
injectedintothecombustionchamberabovethe
engine piston (3), where the extreme engine
compression causes the fuel to self-ignite.
Note:
For information on other maintenance and
adjustmentsoftheengine,refertotheServ-
ice manual „4-Stroke Internal Combustion
Engines“ (5.905-122).
6
1
2
3
4
5
7
8
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10
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KMR 1250 B, LPG, D Unit Functions
Diesel Engine (YANMAR L 70 AE-DE)
Injection pump (cross-section)
Injection pump
The injection cam on the camshaft shuttles the
injection pump piston (1) back and forth. Fuel is
conveyed to the injection nozzle via pressure
valve (7).
Injection timing is determined by the thickness
and number of shims (2) in shim pack.
Note:
Checking injection timing and related fine
adjustment are the exclusive domain of a
licensed service facility.
Intheeventthattheinjectionpumpfailstodeliv-
erfuel,the entire injectionpump assembly must
be removed and checked.
Note:
Injection pump service and repair are the
exclusivedomainofalicensedservicefacil-
ity.
Injector assembly
The fuel that is conveyed to the injector by the
injection pump is transported through the feed
channel(14),pastthenozzlevalve(13),andthen
sprayed into the engine combustion chamber.
Injector assembly (cross-section)
4
3
2
1
56
7
8
9
10
11
13
12
14
1 Pump piston
2 Shim pack
3 Flange
4 Fuel inlet
5 Pressure valve holder
6 Valve spring
7 Pressure valve
8 Housing, injection pump
9 Piston spring
10 Holder, piston spring
11 Housing, injector
12 Valve spring
13 Nozzle valve
14 Fuel feed line

14
Unit Functions KMR 1250 B, LPG, D
Steering and Drive Power
1 RH drive chain
2 Impellerfan
3 Drive belt, impeller fan
4 Drive belt, hydrostatic transmission
5 Hydrostatic transmission
6 LH drive chain
7 Brush roller
8 Drive belt, brush roller
9 Drive belt, LH side brush
(option)
10 LH side brush (option)
11 Chain, steering
12 RH side brush
13 Drive belt, brush roller
14 Drive belt, RH side brush
15 Steering wheel
MEngine
14 6
8
10
7
3
5
4
9
12
11
2
13
15
1
M

15
KMR 1250 B, LPG, D Unit Functions
1 Hydraulicunit
2 Engine B / LPG / D
3 Steering wheel
4 Operator seat
5 Debris container, raised
6 Impellerfan
7 Dust filter
Sweeping system
8 Rear wheel
9 Debris container, lowered
10 Hydrostatic transmission
11 Brush roller
12 Coarse-dirt flap
13 Front wheel
14 Side brush
4
2
1
14 13 12 11 10 9 8
6
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5
3

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Troubleshooting Information KMR 1250 B, LPG, D
Check fuse F1/F2
Fuse F2 protects the entire control voltage cir-
cuitry.ThisfuseislocatedontheA1circuitboard.
– Check fuse and replace as required.
A1 Circuit board
F1 Fuse, motor filter cleaning (10 A)
F2 Fuse, control voltage (7,5 A)
Check battery voltage
– Check battery voltage with voltmeter.
– Check electrolyte level on low-maintenance
battery.
– If required, recharge battery using external
battery charger (e.g., P/N 6.654-046).
Fuses F1/F2 on A1 circuit board
Fuse F4 in electrical box
Checking ignition switch S1 while removed from unit
Check fuse F4 and wiring
Whentheengineisrunning,thebatteryreceives
a steady charge current from the alternator.
The fuse F4 (15 A rating) protects this circuit.
The fuse is located beneath the electrical box.
– Check fuse and replace as required.
– Check all wiring and connections between
alternator and battery.
Check ignition switch S1
– Removescrewsoninstrumentpanel(2),and
carefully lift off instrument panel.
– Check ignition switch (1) for continuity at its
various positions (0, 1, 2).
Key position Connection Function
0 30/1 - 15 EngineStop
1 30- 15/54 Inoperation
2 30 - 50 Starter
Starter Fails to Turn Engine
A1
F1
(10A)
F2
(7,5A)
F4
(15A)
F4 Fuse, generator
1 Ignition switch (S1)
2 Screws, instrument panel
3 Ignition switch, bottom view
1
2
30
15
50
30/1
3
15/54
(15/50)

17
KMR 1250 B, LPG, D Troubleshooting Information
Check voltage on starter solenoid
– Hold ignition switch in position II.
– Measure the voltage between solenoid ter-
minal and vehicle ground.
– If the meter fails to indicate a voltage, wiring
must be checked for possible defect.
– Ifavoltageispresentbut starter fails to turn,
starter is defective and must be replaced.
Note:
The connecting wiring for the starter sole-
noid are not shown in electrical diagram.
Checking voltage on starter motor M1
Checking voltage on starter solenoid
Check starter M1
– Hold ignition switch in position II.
– Ifavoltageispresentbut starter fails to turn,
starter is defective and must be replaced.
Starter Fails to Turn Engine
V
SW
V

18
Troubleshooting Information KMR 1250 B, LPG, D
Check regulator
ORIGINAL
Whentheengineisrunning,thealternatorgener-
ates a continuous current flow. The regulator
automatically adapts this current as required
(dependingonbatterychargestatusandelectri-
cal load).
– Start engine and allow to run.
– Usingaclip-onammeter,measureregulator
charging current on X1 plug coupling (white
wireonmaleconnectororredwireonfemale
coupling of X1 connector).
If a charging current cannot be measured, this
indicatesthatthealternatorisfaultyandmustbe
replaced.
Checking regulator charging current
Starter Fails to Turn Engine
Checking regulator charging current
Check regulator
REVISED
Units of recent manufacture no longer feature
the X1 plug coupling. Wires are connected by
individual round plug couplings instead.
– Start engine and allow to run.
– Usingaclip-onammeter,measureregulator
chargingcurrent on red-and-whitewire cou-
pling.
If a charging current cannot be measured, this
indicatesthatthealternatorisfaultyandmustbe
replaced.
ws White wire
rt Red wire
1 Plug coupling
2 Round male plug w/ female coupling
ws
rt
A
A
1
ws
rt
A
A
2

19
KMR 1250 B, LPG, D Troubleshooting Information
Checking S3 seat contact switch
Note:
Actuating the starter without a load on the
seat will crank the engine but not start it!
– Disconnectwire connections fromseat con-
tact switch.
– Connectanohmmetertocheckseatcontact
switch for continuity.
– Withaphysicalloadontheseatcushion,the
switch opens, and there is no continuity.
– Intheabsenceofaphysicalloadontheseat
cushion, switch contacts are closed.
– Adjust or replace seat contact switch as re-
quired.
Checking spark plug (gasoline & LPG engine)
Checking seat contact switch S3
Check spark plug
(gasoline and LPG engine)
– If ceramic insulator shows signs of break-
ageofcracking,sparkplugmustbereplaced.
– Heavilyfouledsparkplugsmustbereplaced.
– Usingafeelergauge,measureelectrodegap,
and bend electrodes to adjust as required.
– To compress captive seal washer on new
spark plug, screw in plug hand-tight, then
tighten 1/2 turn. Tighten used spark plugs
only by 1/8 to 1/4 turn.
Check oil level switch S9
(gasoline and LPG engine)
In the event that the engine oil level drops down
too far, the oil level switch cuts out the ignition.
This causes the engine to stall and will prevent
engine restarts.
– Remove the terminal of the yellow wire.
– Using the ohmmeter, check the connecting
terminal for continuity.
– Iftheoillevelissufficientlyhigh,therewillbe
no continuity.
– If the oil level is too low, there must be con-
tinuity.
– Top up engine oil or replace oil level switch
as required.
Checking oil level switch S9 (gasoline & LPG
engine)
Starter Turns Engine but Engine Fails to Start
- S3
0,70 - 0,80 mm
0.028 - 0.031 in.

20
Troubleshooting Information KMR 1250 B, LPG, D
Starter Turns Engine but Engine Fails to Start
Check compression release lever (diesel
engine)
– Engineisequippedwithcompressionrelease
lever. During engine starting, it can be actu-
ated for a short while to ease overcoming
engine resistance at top dead center.
Note:
To enable engine to start with hood open,
seat contact switch must be jumpered.
Jumper must again be removed once en-
gine has started.
Fuel filter (diesel engine only)
Compression release lever (diesel engine)
4 2
1
3
5
6
7
Using Diesel fuel (diesel engine)
Exceptionally low outdoor temperatures may
cause diesel fuel to congeal. In this condition,
fuel is no longer supplied to the engine.
– To prevent this condition occurring, add vis-
cosityagents(winterizeddieselfuelordena-
turedalcohol)to the tankbeforecold weath-
er sets in.
– Ifthefuelcongeals,replacefueltankcontent
with winterized diesel fuel or add viscosity
agents.
– Continue by allowing the power sweeper to
warm up in a cold environment, with engine
idling.
1 Oil filler neck
2 Lever, compression release
3 Injectorline
4 Injector
5 Tank filler cap
6 Seal ring
7 Fuelfilter