My friend bought an 86 Firebird, 2.8, 5 speed. When you turn the key, it cranks and fires up, but as soon as you let go of the key for it to run it dies. Someone told him it was the fuel pump, but you can hear it shoot fuel when you turn the key to the on position. Any ideas? Thanks in advance.

 

Could be a bad MAF sensor. The test is to unplug it (3-pin connector, tie it out of the way of the belts & pulleys) and try starting the car. If it starts, the MAF is bad.

The MAF is located on the tubing directly after the air filter box.

A fuel pump can sound as if it's shooting fuel, but really be unable to hold (or give!) decent pressure. I think the absolute minimum (barely running) is around 25-28 PSI?

Don't forget about the V6 message board here, either...


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-Tom P (Hot rodded 1986 Firebird 2.8l) from http://www.f-body.net/mailbag/3rd/3rd_mailbag.html message boards
---Think your car could be pic of the week? Visit http://www.f-body.net for details!

 

That sounds more like the oil pressure switch. There's a relay to work the pump during startup, then when the engine is supposed to be running, the current to run the pump gets there through a contact in the oil press sending unit, so if the motor stops running, the pump shuts off for safety reasons.

So check the oil pressure sending unit. I'm not sure which one or where it is on that motor, or if there's 2 different ones for the FP and the gauge; somebody that knows 6-cyl cars (I don't) would have the answer.

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"So many Mustangs, so little time..."

 

I agree. I forget which relay it is, but you can jump it and see if the car runs. For that matter you can jump the start relay as well. This one is the middle in the relay block.

Either way the fuel pump will get continious power and hopefully answer your question. BTW the relay is like 14 bucks.

William

 

Thanks guys. I was thinking the relay myself, but I couldn't think of what else could be wrong. I didn't get to look at it this afternoon because I had to change a CV boot on my S10. I'll look for these things tommorrow.

 

89,

Rather than futz with the relay and auxilliary oil pressure switch (either of which might be bad), test the fuel pump voltage at the 'G' terminal of the ALDL. If the voltage is present after the engine starts and the key is released to the "RUN" position, the fuel pump is getting voltage.

It's possible, however, that the ignition system is not. Perform the same test at the ignition coil primary feeder to see if voltage is present with the key in the "RUN" position. If not, start looking at the switch, wiring, or ECM. If you have a VATS module, you might want to check that, too.

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Later,
Vader
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"No matter how hard you try you can't stop us now"
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