G424 Service Manual Adjustment and Troubleshooting186
Problem Probable Cause Probable Solution
Poor High Speed Restricted exhaust system Check exhaust system
Performance/Lean • Measure exhaust back-pressure
Condition • Compare to specs
Engine mechanical See Troubleshooting section
Excessive Fuel Carburetor malfunction Check carburetor
Consumption/LPG • Remove air/gas valve assembly
Exhaust Smell/Closed • Clean air/gas valve and carb throat
Loop System Not • Check diaphragm for holes/damage
Working • Check air/gas valve for wear/damage
• Repair/replace as required
Incorrect ignition timing Check ignition timing
setting • Measure timing @ low idle
• Measure timing advance @ run
Incorrect full load air/fuel duty Verify full load air/fuel duty cycle
cycle
Engine mechanical See Troubleshooting section
Pressure regulator Test pressure regulator operation
malfunction • 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
Air filter clogged Check air filter
• Clean/replace as required
Weak ignition miss fire See ignition system section
Vacuum Leak Replace fuel system vacuum hoses
Fuel pressure too high Replace/rebuild regulator.
Exhaust system leaks Repair exhaust system
Oxygen sensor failure Replace/reconnect oxygen sensor
FCV failure Replace/reconnect FCV
Commander failure Replace/reconnect commander