G424 Service Manual Adjustment and Troubleshooting184
Problem Probable Cause Probable Solution
Engine Stalls 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
Pressure regulator freezes Check level in cooling system
• Must be full
Check coolant strength
• -35F minimum
Check regulator mounting position
• Must be below top of radiator
Check coolant hoses
• Watch for kinks and/or pinched hoses
• Verify one pressure hose and one return
hose
Faulty vapor connection Check connection
between pressure regulator • No holes in hose
and carburetor • Clamps must be tight
• Watch for kinked and/or pinched and/or
collapsed hose
Carburetor malfunction 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
Engine Mechanical See Troubleshooting section
Rough Idle/Weak Incorrect idle speed setting Check idle speed and adjust if necessaly
Ignition/Lean Condition
Incorrect full load air/fuel duty Verify full load air/fuel duty cycle
cycle
Faulty vapor connection Check connection
between pressure regulator • No holes in hose
and carburetor • Clamps must be tight
* Watch for kinked and/or pinched and/or
collapsed hose
Vacuum leaks Check for vacuum leaks
• Between carburetor and intake manifold
• Between intake manifold and cylinder head
Engine mechanical See Troubleshooting section
High Idle Speed Incorrect idle speed setting Check idle speed
• Adjust idle speed
Sticking throttle Check throttle
• Repair replace as required
Engine mechanical See Troubleshooting section
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