Doosan G20P-5, Service Manual, Page: 246 / 306

G424F(FE) Service Manual 244 Chapter 8. Basic Troubleshooting
Poor Fuel Economy / Excessive Fuel Consumption LPG Exhaust Smell
Fuel economy, as measured during normal operation, is noticeably lower than expected. Also, economy is
noticeably lower than what it has been in the past. Propane fuel smell near vehicle sets off carbon monoxide
sensors.
PRELIMINARY CHECKS
Perform the visual checks as described at start of “ Basic Troubleshooting” chapter.
Verify operator complaint: identify operating conditions.
Check operator’s driving habits:
Are tires at correct pressure?
Are excessively heavy loads being carried?
Is acceleration too much, too often?
Check air cleaner element (filter) for being dirty or plugged.
Visually (physically) check vacuum hoses for splits, kinks, and proper connections as shown on application
manual.
PROBABLE CAUSE CORRECTIVE ACTION
Fuel system
malfunction
Check for faulty gasoline pressure regulator.
Check for leaking injector.
Check that dither valve duty cycle is < 15%.
Check for too high propane pressure at mixer
(> 1” positive pressure).
Monitor Pre-catalyst O2 sensor with Service Tool.
Cooling system
malfunction
Check engine coolant level.
Check engine thermostat for faulty part (always open) or for
wrong heat range.
Ignition system
malfunction
Check ignition timing. Refer to application manual.
Check for weak ignition and/or spark control.
Check spark plugs. Remove spark plugs and check for wet
plugs, cracks, wear, improper gap, burned electrodes, or heavy
deposits. Repair or replace as necessary.
Component malfunction
Check for exhaust system restriction or leaks.
Check induction system and crankcase for air leaks.
Check for clogged air filter; clean or replace as required.
Check FTV for housing cracks or obstructions; repair or replace
as required.
Check for vacuum leak. Check system vacuum hoses from
regulator to FTV and mixer. Repair or replace as required.
Air/fuel mixer malfunction Check mixer.
Pressure regulator malfunction /
fuel pressure too high
Test regulator operation and pressure.
See Chapter 6 Tests and Adjustments.
Engine mechanical
Check compression.
Refer to Chapter 3 Engine Mechanical System.
Related MIL Faults:
Pre-catalyst O2 sensor faults / Low side driver / Dither valve duty cycle
EST faults / Fuel adapt faults / Low coolant temperature