87 TBI Engine Won't Stay Running

[KrazyRay]

I have an 87 Suburban with a 5.7 tbi. Every time I start it up it runs great for 15 seconds and dies. It will start right up again for another 15 seconds and it will die again. The fuel pump is working fine. Any ideas what could be wrong?
Thanks,
Ray

[SkinnyG]

I don't know TBI intimately, but...

Does the fuel pump need an oil pressure switch triggered to keep it running? The ECU should run the fuel pump initially to prime the fuel system, and run the pump to fire the engine, but the ECU will need something to know the engine is still running so the pump is shut off in the event of a collision.

Just a guess.

[rfmaster]

1) Observe SES light during initial ignition key turn sequence - off to run position (do not crank). It should be solid, blink off, solid on. During Power on self test (POST) fuel pump (FP) must turn on for about 2 seconds and shut off. This will confirm if FP relay circuit is functional.

2) Check fuel pump relay and socket. It is common for FP relay socket contacts to oxidize or Relay contacts to go bad.

3) Check oil pressure switch and socket. If oil pressure back-up switch is disconnected engine will stall if FP relay is malfunctioning.

4) Low fuel pressure - very common for in tank fuel hose to burst. This results in just enough fuel reaching injectors to fire engine.

Post your findings

//RF

[Just call me Sean]

For any fuel injected vehicle always check for codes first.

[KrazyRay]

I ran a jumper wire across the oil pressure switch to make sure the fuel pump is working. I also let the engine idle until it died at 15 seconds. Then I revved the engine and it still ran for 15 seconds and died. There must be a relay causing the ECU to shut it down after 15 seconds.

[rfmaster]

Originally Posted by KrazyRay

I ran a jumper wire across the oil pressure switch to make sure the fuel pump is working. I also let the engine idle until it died at 15 seconds. Then I revved the engine and it still ran for 15 seconds and died. There must be a relay causing the ECU to shut it down after 15 seconds.

That is not correct.

If you jumper oil pressure switch socket the fuel pump will operate continuously. Now the ECM will stop firing injectors if it looses DRP signal from distributor. No distributor pulses, ECM stops pulsing injectors.

//RF

[odee]

I would check power to idle air motor also. I have also seen the map sensor short out internally and do this. May want to unplug coolant temp sensor, could be giving computer false hot reading.