Doosan G430 LP Service Manual page 42

Problem
Poor High Speed
Performance/Lean
Condition
Excessive Fuel
Consumption/LPG
Exhaust Smell/Closed
Loop System Not
Working
LP Engine G430 (3.0L)
Probable Cause
Restricted exhaust system
Engine mechanical
Carburetor malfunction
Incorrect ignition timing
setting
Incorrect full load air/fuel duty
cycle
Engine mechanical
Pressure regulator
malfunction
Air filter clogged
Weak ignition miss fire
Vacuum Leak
Fuel pressure too high
Exhaust system leaks
Oxygen sensor failure
FCV failure
Commander failure
Check exhaust system
Measure exhaust back-pressure
Compare to specs
See Troubleshooting section
Check carburetor
Remove air/gas valve assembly
Clean air/gas valve and carb throat
Check diaphragm for holes/damage
Check air/gas valve for wear/damage
Repair/replace as required
Check ignition timing
Measure timing @ time position
Measure timing advance @ run position
Verify full load air/fuel duty cycle
See Troubleshooting section
Test pressure regulator operation
Use test kit
Install primary pressure gauge
Install secondary pressure gauge
Crank engine and observe readings on
pressure gauges
Compare readings to specifications
If readings are out of spec repair/replace
pressure regulator
Check air filter
Clean/replace as required
See ignition system
Replace fuel system vacuum hoses
Replace/rebuild regulator.
Repair exhaust system
Replace/reconnect oxygen sensor
Replace/reconnect FCV
Replace/reconnect commander
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Probable Solution
Troubleshooting