G420E/G424E
Tier
LP Engine
Basic Troubleshooting
42
Problem Probable
Cause
Corrective
Action
Incorrect Idle speed control
Incorrect timing or spark control
See Chapter 5 Advanced Diagnostics &
Chapter 9 Tests and Adjustments
Rough Idle
Engine Mechanical
See Engine Manufacturers Service Manual
Incorrect Idle speed control
Throttle sticking
See Chapter 5 Advanced Diagnostics &
Chapter 9 Tests and Adjustments
High Idle Speed
Acceleration Pedal sticking or
incorrect pedal signal
Check pedal return spring travel for binding
z
See Chapter 5 Advanced Diagnostics
Clogged fuel filter
Repair/replace as required
z
See Chapter 3 Fuel Filter replacement
Plugged fuel line
Remove obstruction from the fuel line
z
Close liquid fuel valve
z
Using caution, disconnect the fuel line
(some propane may escape)
z
Clear obstruction with compressed air
z
Re-connect fuel line
z
Slowly open liquid fuel valve & Leak test
Air filter clogged
Check air filter
z
Clean/replace as required
Faulty vapor connection between
the pressure regulator/converter
and the mixer
Check connection
z
Verify no holes in hose
z
Clamps must be tight
z
Look for kinked, pinched and/or
collapsed hose
Pressure regulator malfunction
Test pressure regulator operation
z
See Chapter 9 Tests and Adjustments
Air/Fuel Mixer malfunction
Check mixer
z
See Chapter 8 Air/Fuel mixer section
Restricted exhaust system
Check exhaust system
z
Measure exhaust back pressure
Incorrect ignition control
Incorrect air/fuel control
Poor High Speed
Performance
Incorrect throttle position
See Chapter 5 Advanced Diagnostics &
Chapter 9 Tests and Adjustments
