Fuel Line; Fuel Pump; Fuel Pump Replacement; Fuel System Tests - Kohler CH940-CH1000 Service Manual

Fuel System and Governor
Fuel Recommendations
Explosive Fuel can cause fi res and severe
burns.
Do not fi ll fuel tank while engine is hot or
running.
Gasoline is extremely fl ammable and its vapors can
explode if ignited. Store gasoline only in approved
containers, in well ventilated, unoccupied buildings,
away from sparks or fl ames. Spilled fuel could ignite
if it comes in contact with hot parts or sparks from
ignition. Never use gasoline as a cleaning agent.
NOTE: E15, E20 and E85 are NOT approved and
should NOT be used; effects of old, stale or
contaminated fuel are not warrantable.
Fuel must meet these requirements:
● Clean, fresh, unleaded gasoline.
● Octane rating of 87 (R+M)/2 or higher.
● Research Octane Number (RON) 90 octane minimum.
● Gasoline up to 10% ethyl alcohol, 90% unleaded is
acceptable.
● Methyl Tertiary Butyl Ether (MTBE) and unleaded
gasoline blend (max 15% MTBE by volume) are
approved.
● Do not add oil to gasoline.
● Do not overfi ll fuel tank.
● Do not use gasoline older than 30 days.

Fuel System Tests

When the engine starts hard, or turns over but will not start, it is possible that the problem is in the fuel system. To fi nd
out if the fuel system is causing the problem, perform the following test.
Troubleshooting -- Fuel System Related Causes
Check for fuel in combustion chamber.
1. 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.
Check for fuel fl ow from tank to fuel pump.
2. a. Remove fuel line from inlet fi tting of fuel pump.
b. Hold line below bottom of tank. Open shut-off
valve (if so equipped) and observe fl ow.
Check operation of fuel pump.
3. a. Remove fuel line from inlet fi tting of carburetor.
b. Crank engine several times and observe fl ow.
22
WARNING
Test
KohlerEngines.com

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 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 fi ttings.
Note orientation.
2. Follow procedure for replacing valve cover.
3. Reconnect fuel lines to inlet and outlet fi ttings and
secure with clamps.
Conclusion
1. If there is fuel at tip of spark plug, fuel is reaching
combustion chamber.
If there is no fuel at tip of spark plug, check for fuel
fl ow from fuel tank (step 2).
2. If fuel does fl ow from line, check for faulty fuel pump
(step 3).
If fuel does not fl ow from 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.
3. If fuel does fl ow from line, check for faulty carburetor.
If fuel does not fl ow from line, check for a clogged
fuel line. If fuel line is unobstructed, check for
overfi lled crankcase and/or oil in pulse line. If none of
checks reveal cause of problem, replace pump.
62 690 01 Rev. C