Service manual

G420F(FE) Service Manual 264 Chapter 8. Basic Troubleshooting
Engine Cranking but Will Not Start / Difficult to Start (cont’d.)
PROBABLE CAUSE CORRECTIVE ACTION
SECM / control system
malfunction
Check Coolant Temperature Sensor using the Service Tool; compare coolant
temperature with ambient temperature on cold engine.
If coolant temperature reading is 5° greater than or less than ambient air
temperature on a cold engine, check resistance in coolant sensor circuit or
sensor itself. Compare CTS resistance value to “Diagnostic Aids” chart at end
of this section.
Verify that there is no code for ETC spring check fault.
Check for 0% APP during cranking.
Cycle key ON and OFF and listen for throttle check (movement) on key OFF.
Check for oil pressure switch faults.
Check for sensor “sticking” faults.
Check TPS for stuck binding or a high TPS voltage with the throttle closed.
Fuel system malfunction
Check fuel lock off (propane) or fuel pump relay gasoline operation: actuator
should turn “ON” for 2 seconds when ignition is turned “ON”.
Check fuel pressure.
Check for contaminated fuel.
Check both gasoline injector and lock off fuses (visually inspect).
Check propane tank valve & pickup. A faulty
in-tank fuel pump check valve will allow the fuel in the lines to drain back to the
tank after engine is stopped. To check for this condition, perform fuel system
diagnosis.
Check FTV system for proper operation.
Ignition system malfunction
Check for proper ignition voltage output with spark tester.
Check spark plugs. Remove spark plugs, check for wet plugs, cracks, wear,
improper gap, burned electrodes, or heavy deposits. Repair or replace as
necessary.
Check for:
• Moisture in distributor cap*
• Bare or shorted wires
• Worn distributor shaft/rotor*
• Loose ignition coil ground
• Pickup coil resistance and connections*
(*) Where present
Related MIL Faults:
ETC spring check / ETC faults / EST faults / TPS conflict
APP faults / Encoder error / MAP faults
Injector faults / Oil pressure faults