Kohler COMMAND CH18-745 User Manual download pdf (Page 49)

5A.2

Section 5A

LPG Fuel Systems

Operation

In a liquid withdrawal system, the Liquefied Petroleum

Gas (LPG) is released from the bottom of the supply

tank under high pressure. Upon opening the shut-off

valve on the tank, liquid fuel travels out through the

high pressure line to the electric lock-off/filter

assembly. The lock-off opens internally when the key

switch is turned “on,” permitting filtered fuel to flow to

the vaporizer. The vaporizer is mounted in the flow of

the discharged cooling air. It absorbs heat from the

cooling air and transfers it to the fuel, changing the

liquefied petroleum to a vapor or gaseous state, while

partially stepping down the fuel pressure. The gas/

vapor flows under this decreased pressure to the

regulator where it is further reduced to a usable,

regulated pressure. The regulator, activated by intake

manifold vacuum, controls fuel flow to the carburetor.

In the venturi of the carburetor, the fuel vapor is mixed

with incoming air from the air cleaner in the correct

ratio for efficient combustion.

Troubleshooting Checklist

If the engine starts hard, runs roughly, or stalls, check

the following areas.

• Make sure the LPG fuel tank is filled and shut-off

valve is fully opened.

• Make sure fuel is reaching the carburetor.

• Make sure the air cleaner element and precleaner

are clean and all components are fastened

securely.

• Make sure the ignition, governor, exhaust, throttle,

and choke control systems are all operating

properly.

• Check compression.

If engine continues to start hard, run roughly, or stall

after these checks have been made, use the following

troubleshooting guide.

Engine cranks but will not start

1. LPG fuel tank closed, low, or empty.

2. Lock-off not opening electrically, preventing fuel

flow to vaporizer.

3. Fuel filter (located inside lock-off) dirty or blocked.

4. Insufficient vacuum signal, regulator not opening.

a. Vacuum line between carburetor and regulator

cracked, leaking, kinked, or pinched.

b. Carburetor loose.

c. Intake manifold loose or leaking.

d. Excessive internal engine wear.

5. Faulty regulator.

a. Primary valve not opening.

b. Diaphragm spring adjustment incorrect.

c. Idle adjustment screw incorrectly set.

d. Vent(s) blocked/restricted.

6. Restricted/blocked fuel line.

7. Blocked carburetor fuel circuit.

8. Loose/leaking fuel enrichment hose (Impco

carburetor system).

Hard starting, runs roughly, or stalls at idle speed

1. LPG fuel tank low.

2. Vacuum line between carburetor and regulator

pinched, cracked, or leaking.

3. Carburetor idle speed set too low (should be at

least 1200 RPM).

4. Carburetor idle circuit restricted.

5. Dirty/restricted air cleaner.

6. Dirty/restricted lock-off filter.

7. Frozen/malfunctioning regulator. Check/adjust

primary pressure.

8. Excessive external load on engine.

9. Excessive internal wear.

10. Loose/leaking fuel enrichment hose (Impco

carburetor system).

Irregular or inconsistent idle

1. Improper operation/adjustment of regulator, idle

adjustment screw, throttle opening, and/or engine

governor.

2. Secondary valve in regulator not closing. Readjust

idle screw (couterclockwise) so valve can close

fully against seat.

3. Loose/leaking vacuum line.

4. Loose carburetor mounting and/or line

connections.

5. Damaged diaphragm(s) within regulator.

6. Debris in regulator. Flush debris from drain plug

or remove regulator from system, disassemble

body and remove debris.

7. Dirt or debris in carburetor. Remove carburetor,

disassemble and clean/service as required. If

venturi (Impco carburetor) removal is performed,

mark its orientation to the carburetor body for

proper reinstallation.

8. Loose/leaking fuel enrichment hose (Impco

carburetor system).

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Kohler COMMAND CH18-745 User Manual Page 49

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