ENGINE AND ENGINE SYSTEMS 5540F/YB5515 SERVICE MANUAL
6-24 Published 10-21-2010, Control# 198-04
The following is a guide to the most common engine
performance complaints. The guide is to be used to
diagnose problems that are due to worn out components
and/or basic adjustments in the fueling system.
CONDITION: Engine will not start (Gasoline)
CONDITION: Engine runs too rich on gasoline
CONDITION: Engine runs lean or misfires on gasoline
CONDITION: Engine runs lean or misfires on LPG
Verify each item below: Remedy for each item:
Fuel tank level. Add fuel.
Check fuel pump. Cycle
ignition switch ON/OFF,
fuel pump should run for 2
seconds.
Check wiring and fuse/
relay.
Use a pressure gauge
connected to the fuel port.
Verify the fuel pressure
reads between 40-50 psi
(276-310 kPa).
Check and replace fuel
filter.
Check and replace fuel
pressure regulator.
Check and replace fuel
pump.
Fuel injector is spraying. Check fuel injector wiring.
Fuel injector is not leaking.
Replace injector o-ring or
injector.
Spark plugs are not fouled
or wet.
Disconnect the fuel
injectors connectors for 15
seconds while cranking to
unflood the engine.
Verify each item below: Remedy for each item:
Check for vacuum leaks to
the MAP sensor.
Replace the hose.
Restricted fuel return line. Replace the fuel line.
LPG shut-off valve does
not close.
Shut off LPG tank valve
and then replace or clean
the LPG shut-off valve.
Check fuel pressure.
Should be between
40-50 psi (276 - 310 kPa)
at the fuel port.
Replace pressure
regulator.
Check for a bad MAP
sensor.
Replace with a new MAP
sensor.
Check for a bad IAT, ECT
sensor.
Replace with a new sensor.
Check for exhaust leaks
before the O2 sensor.
Repair leaks in the exhaust
system.
Check for excessive smoke
while running.
Check and replace fouled
spark plugs.
Verify each item below: Remedy for each item:
Visually inspect fuel filters
for restriction.
Replace fuel filter.
Use a pressure gauge
connected to the fuel port.
Verify the fuel pressure
reads between 40-50 psi
(276-310 kPa).
Replace pressure
regulator.
Check for clogged fuel
injectors.
Clean or replace fuel
injectors
Visually inspect MAP
sensor hose for breaks.
Replace the hose.
Check for a bad MAP
sensor.
Replace with a new MAP
sensor.
Check for a bad IAT, ECT
sensor.
Replace with a new IAT
sensor.
Check for intake manifold
air leaks.
Repair leaks in the intake
system.
Verify each item below: Remedy for each item:
LPG filter is not
contaminated and use air
pressure to verify
restriction.
Replace LPG filter.
Check for clogged fuel
lines.
Clean fuel lines.
LPG pressure regulator/
vaporizer is not frozen or
icing.
Check for air leaks, purge
air from coolant hoses, add
coolant.
Visually inspect vacuum
hoses for breaks.
Repair as necessary.
Verify timing with a timing
light.
Adjust distributor timing.
Verify that the air filter for
the vaporizer is not
clogged.
Replace air filter.
Vaporizer primer button
becomes hard to depress
when the fuel is present.
Replace or clean the LPG
fuel lock-off.
Reference Only
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