Operation Section
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Problem Probable Cause Corrective Action
Fuel Lock-off malfunction Repair/replace Fuel Lock-off
z See G643E Engine Service Manual
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 freezes Check level in cooling system
z Must be full, check coolant strength
z -35F minimum
Check coolant hoses
z Watch for kinks and/or pinched hoses
z Verify one pressure hose and one
return hose
Pressure regulator malfunction Test pressure regulator operation
z See G643E Engine Service Manual
Vacuum leak Check for vacuum leaks
z Between mixer and throttle body
z Between throttle body and intake
manifold
z Between intake manifold and cylinder
head
Air/Fuel Mixer malfunction Check mixer
z See G643E Engine Service Manual
Engine Stalls
Engine Mechanical See Engine Manufacturers Service Manual
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 G643E Engine Service Manual
Vacuum leak Check for vacuum leaks
z Between mixer and throttle body
z Between throttle body and intake
manifold
z Between intake manifold and cylinder
head
Rough Idle
Air/Fuel Mixer malfunction Check mixer
z See G643E Engine Service Manual