Fuel Pump; Fuel System Tests - Kohler Command PRO Service Manual

Typical carbureted fuel system and related components
include:
● Fuel tank and valve.
● Fuel lines.
● In-line fuel filter.
● Fuel pump.
● Carburetor.
Fuel from tank is moved through in-line filter and fuel
lines by fuel pump. Fuel then enters carburetor float 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 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 flow from tank to fuel pump.
a. Remove fuel line from inlet fitting of fuel pump.
b. Hold line below bottom of tank. Open shut-off
valve (if equipped) and observe flow.
Condition
Fuel at tip of spark plug.
No fuel at tip of spark plug.
Fuel flows from fuel line.
No fuel flow from fuel line.
Fuel line condition.
62 690 01 Rev. J
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Fuel is reaching combustion chamber.
Check fuel flow from fuel tank (step 2).
Check for faulty fuel pump (step 3).
If fuel pump is working, check for faulty carburetor. Refer
to Carburetor.
Check fuel tank cap vent, fuel pickup screen, in-line
filter, shut-off valve, and fuel line. Correct any observed
problem and reconnect line.
Check for a clogged fuel line. If fuel line is unobstructed,
check for overfilled crankcase and/or oil in pulse line. If
checks don't reveal cause of problem, replace pump.
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FUEL PUMP

These engines use either a mechanical fuel pump, or
optional remote-mounted electric fuel pump assembly.
Operation of mechanical fuel pump occurs by direct
lever/pump actuation off rocker arm movement. 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, internal check valves prevent fuel from
going backward through pump.
Fuel Pump Replacement
Mechanical fuel pump is an integral part of valve cover
assembly and not serviced separately.
1. Disconnect fuel lines from inlet and outlet fittings.
Note orientation.
2. Follow procedure for replacing valve cover. Refer to
Disassembly and Reassembly.
3. Reconnect fuel lines to inlet and outlet fittings and
secure with clamps.
3. Check operation of fuel pump.
a. Remove fuel line from inlet fitting of carburetor.
b. Crank engine several times and observe flow.
Conclusion
Fuel System
29