Engine will not start

Tiny
LANCEWILFRED
  • MEMBER
  • 1987 CHEVROLET SUBURBAN
Engine problem V8 Two Wheel Drive Automatic 267519 miles

I have a 1987 chevy suburban r20 with a 5.7 tbi the engine will not start unless you poor fuel down the tbi. Then it will run until the fuel is burned off.I noticed that there is no fuel flow from the injectors. I have already replaced the fuel pump and the injector fuel pressure regulator and the fuel filter still no fuel flow at the injectors. The fuel pump pressure is good the pump comes on when you turn on the switch also while cranking. The fuel pump relay is good.
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Wednesday, January 2nd, 2008 AT 7:51 AM

4 Replies

Tiny
JUSTGOTMEAJETTA
  • MEMBER
The ECM operates the fuel pump relay for three seconds or so when the key is turned to run. Then, as long as the ecm is recieving a signal from the crank sensor that the engine is cranking over, it will continue to operate the fuel pump relay.

There is another system to power the fuel pump directly, once the engine starts, and that is an oil pressure switch. As long as there is at least 4 PSI of oil pressure, that switch will send power to the fuel pump, weather the ECM operates the relay or not.
That would explain why yours runs after dribbling the gas. The oil pressure builds up, and the oil switch runs the pump, and all is well.

Your problem, then, is that the relay isn't sending power.

That could be because the relay, or a wire associated with it is bad, the ECM isn't sending power to the relay, or the crank sensor isn't sending a signal to the ECM.

Maybe this will help you. Just an idea ;)
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Wednesday, January 2nd, 2008 AT 7:19 PM
Tiny
LANCEWILFRED
  • MEMBER
The fuel pump is working like it should has pressure just the injecters will not spray the fuel into the intake
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Saturday, January 5th, 2008 AT 6:07 AM
Tiny
WIDEBODY
  • MEMBER
Check the ECM fuse. It's most likely blown
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Wednesday, September 14th, 2011 AT 10:28 PM
Tiny
JDL
  • EXPERT
Without rpm signal, no injector pulse. Do you have voltage to the injector/s with key on?

With distributor ignition, the rpm signal comes from the pickup coil to ignition module to computer. It's not the pickup coil.
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Sunday, September 25th, 2011 AT 7:51 PM

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