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99 gmc sierra 4. 3 stalls and loses spark



Ok my truck is a 99 gmc sierra 4. 3 auto ac. I bought this truck a week ago and i cant figure out this problem. It runs fine then it just stalls and loses spark. I staryed by changing the coil and icm. That didn't work so i changed the crank sensor and distributor. That still didn't work so i changed the pcm. Still same thing. Usually the thing stalls and starts back up but sometimes it stalls and wont start. I took it to an auto electric place today and they charged me 300 bucks and told me it was the fuel pump. They claim it had spark the whole time they were messing with it and that the fuel pressure was lower then sixty. I called bull shi# and drove the truck home. Let it run in the driveway and it stalled again and no spark again. I just put 1000 bucks into this truck and painted it and the only good auto electric guys in town screwed me. I just dont know what to do now. I am a skilled mechanic and i cant figure this out. Any help would greatly be appreciated.

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You don't actually say that you had them change the fuel pump. Did you? If you did, then hand it back to them and tell them it obviously was not the pump, please fix it this time. If you did not have it changed, then they did nothing wrong for you to say they screwed you.


Most skilled mechanics I know are quite adept at troubleshooting something as basic as no spark. It is really a pretty basic system. Best thing for you to try is first stop throwing parts at it, and then find and follow a proper troubleshooting flow chart online. You have the best situation to fix this correctly the first time, it is staying in the no spark condition long enough to troubleshoot it logically.

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No i did let them change the fuel pump. I didn't think much of the problem when i bought the truck because usually a intermittent spark problem is the icm. I pretty much have a auto wrecker in my back yArd so that's why i just though parts it. Coil icm distributor crank sensor and pcm as far as i know with my knowledge pretty much makes up the ignition system. I dont know much about auto wiring so i dont know where to start there. I was just hoping i was missing g something. I basically have 4000$ worth of scrap if i cant figure this out. I knew it was a intermittent spark problem walking in the door and for them to tell me the fuel pump needs replacing for 1200$ i ran with tail between legs. I was hoping someone could shed some light on this because i spent a lot of money and cant drive my truck

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