Help!!! Shutting off issue

Discussion in 'Engine Performance + Maintenance' started by Matt Conner, Jan 11, 2020.

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  1. Matt Conner

    Matt Conner The louder the better

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    So, 1990 GMC k1500 was a 4.3 now a 305, runs great for 15-20 minutes then just shuts off. Kills spark and kills the injectors. Was doing the same thing before then I put another new distributor in it and it solved the issue for 4-5 days then started doing it again. Has good fuel pressure, new coil, new ESC module, all new distributor, new temp sensor. Base timing is set to 0* before TDC. Changed the ICM in hopes of that being the issue, no fix. Could it be the pickup coil in the distributor? Would that shut it down like that? It only shuts down when it semi warms up. I’m stumped. Can someone give me any ideas on where to look. Please help, I have no idea where to look. Thanks in advance.
     
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  2. Matt Conner

    Matt Conner The louder the better

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    Also changed the fuel filter
     
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  3. cngodfather

    cngodfather I'm Awesome

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    How do you know it kills the injectors?
     
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  4. Matt Conner

    Matt Conner The louder the better

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    With the air cleaner off I shine a flashlight on the spray and when it dies the injectors just shut off just like if someone were to turn the key off.
     
  5. Dover

    Dover OBS Enthusiast

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    If it’s cutting fuel flow could be a bad fuel pump relay, loose wire or short somewhere along the fuel pump power wires, or oil pressure sending unit is bad making ECM think it has no oil and shutting down the fuel.


    Sent from my iPhone using Tapatalk
     
  6. Matt Conner

    Matt Conner The louder the better

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    It has a new oil pressure sender, and the pump runs like it should, when it shuts off, file stops spraying Untill the engine shuts completely off then it sprays a small amount of fuel after it’s shut off.
     
  7. Matt Conner

    Matt Conner The louder the better

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    It starts completely fine when cold. And will run Untill warm then shut off. If you let it cool for 10-15 mins it will fire right back up until it gets warm and shuts off again.
     
  8. Schurkey

    Schurkey I'm Awesome

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    1. Usual advice to connect a scan tool so you can look at the data stream.

    2. Any chance this is an open-loop/closed loop problem? As in, it runs in open loop, and dies in closed loop? So you could disconnect the wire from the O2 sensor, and it'd run (crappy) long after it warmed-up?
     
  9. cngodfather

    cngodfather I'm Awesome

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    Kinda sounds like an intermittant power problem to the ecu. something that works ok when cold but breaks electrical connection when warm. I think I would concentrate on looking at connections and grounds.
     
  10. Matt Conner

    Matt Conner The louder the better

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    The truck doesn’t have any o2 sensors on it. It only had one on it and when I had the exhaust put on they took the one out.
     
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