Stalling Mystery

[jimjafarian]

I need all the help I can get with this one. I have a 1990 GMC Jimmy police package that has not been very well taken care of by the department and it has a problem with stalling at idle(without stumble or warning just cutting out). It drives and stops but sitting at a stoplight it has a tendency to stall but not every time, but frequently enough to be a problem. This problem occurs only when the engine is at idle rpm and has happened in a parking lot while rolling. I have replaced the entire ignition system (plugs to coil to distributor), fuel filter, flex plate, transmission fluid, and other basic maintenance items. Everything is stock and I have even taken it to a very reputable local shop and they have yet the diagnose it. I am truly stumped and need your help, thanks in advance.

Andrew

 

[Bent77]

Intake Air controller and passage are probably dirty and/or need replacement

 

[rampage]

Air may be getting into the fuel system via the rubber hose that connects the fuel pump to the sending unit. The original hoses were not designed to tolerate the new gas and tend to split or just develope cracks due to age. One way to test this out is to keep the fuel tank full so this hose is always submerged.

 

[jimjafarian]

Air may be getting into the fuel system via the rubber hose that connects the fuel pump to the sending unit. The original hoses were not designed to tolerate the new gas and tend to split or just develope cracks due to age. One way to test this out is to keep the fuel tank full so this hose is always submerged.

It stall's on a full tank so I don't think that's the problem but thank's anyways.

 

[jimjafarian]

Intake Air controller and passage are probably dirty and/or need replacement

I cleaned the part and system (the idea air controler) and it has not stalled yet, but only time will tell. Thanks a lot for your help.

 

[Bent77]

Keep that fuel hose issue in the back of your mind. It will happen some day...

 

[Hogback Fabrication]

Does the speedometer work right?

 

[jimjafarian]

Does the speedometer work right?

Yes, the speedometer is completely accurate.