Typical carbureted fuel system and related components
include:
●
Fuel tank and valve.
●
Fuel lines.
●
In-line fuel
fi
lter.
●
Fuel pump.
●
Carburetor.
Fuel from tank is moved through in-line
fi
lter and fuel
lines by fuel pump. Fuel then enters carburetor
fl
oat bowl
and is drawn into carburetor body and mixed with air.
This fuel-air mixture is then burned in engine combustion
chamber.
FUEL RECOMMENDATIONS
Refer to Maintenance.
FUEL LINE
Low permeation fuel line must be installed on carbureted
Kohler Co. engines to maintain EPA and CARB
regulatory compliance.
FUEL PUMP
These engines use either a mechanical pump or a pulse
style fuel pump. Pumping action of pulse style pumps is
created by oscillation of positive and negative pressures
within crankcase. This pressure is transmitted to pulse
pump through rubber hose connected between pump
and crankcase. Pumping action causes diaphragm on
inside of pump to pull fuel in on its downward stroke
and to push it into carburetor on its upward stroke. Two
check valves prevent fuel from going backward through
pump.
Performance
Minimum fuel delivery rate must be 7.5 L/hr. (2 gal./
hr.) with a pressure at 0.3 psi and a fuel lift of 24 in. A
1.3 L/hr. (0.34 gal./hr.) fuel rate must be maintained at
5 Hz.
Fuel Pump Replacement
Pulse Fuel Pump
NOTE: Make sure orientation of new pump is consistent
with removed pump. Internal damage may occur
if installed incorrectly.
To replace pulse pump follow these steps. Note
orientation of pump before removing.
1. Disconnect fuel lines from inlet, outlet, and pulse
fi
ttings on fuel pump.
2. Remove screws and take off pump.
3. Connect pulse line to new fuel pump and make sure
opposite end is properly connected to
fi
tting on
crankcase.
4. Attach new fuel pump using screws. Torque screws
to 2.3 N·m (20 in. lb.).
5. Reconnect fuel lines to inlet and outlet
fi
ttings and
secure with clamps.
Mechanical Pump
Mechanical fuel pump is an integral part of valve cover
assembly and not serviced separately.
1. Disconnect fuel lines from inlet and outlet
fi
ttings.
Note orientation.
2. Follow procedure for replacing valve cover. Refer to
Disassembly and Reassembly.
3. Reconnect fuel lines to inlet and outlet
fi
ttings and
secure with clamps.
FUEL SYSTEM TESTS
When engine starts hard or turns over but will not start, fuel system might be causing problems. Test fuel system by
performing following test.
1. Check for fuel in combustion chamber.
a. Disconnect and ground spark plug leads.
b. Close choke on carburetor.
c. Crank engine several times.
d. Remove spark plug and check for fuel at tip.
2. Check for fuel
fl
ow from tank to fuel pump.
a. Remove fuel line from inlet
fi
tting of fuel pump.
b. Hold line below bottom of tank. Open shut-off
valve (if equipped) and observe
fl
ow.
3. Check operation of fuel pump.
a. Remove fuel line from inlet
fi
tting of carburetor.
b. Crank engine several times and observe
fl
ow.
Condition
Conclusion
Fuel at tip of spark plug.
Fuel is reaching combustion chamber.
No fuel at tip of spark plug.
Check fuel
fl
ow from fuel tank (step 2).
Fuel
fl
ows from fuel line.
Check for faulty fuel pump (step 3).
If fuel pump is working, check for faulty carburetor. Refer
to Carburetor.
No fuel
fl
ow from fuel line.
Check fuel tank cap vent, fuel pickup screen, in-line
fi
lter, shut-off valve, and fuel line. Correct any observed
problem and reconnect line.
Fuel line condition.
Check for a clogged fuel line. If fuel line is unobstructed,
check for over
fi
lled crankcase and/or oil in pulse line. If
checks don't reveal cause of problem, replace pump.
Fuel System
21
24 690 34 Rev. D
KohlerEngines.com
