Mechanics

WONT IDLE WELL, OR DIES LIKE THE FUEL IS BEING CUT OFF.

1991 Pontiac Firebird • 6 cylinder 2WD Automatic • 150,000 miles

I have a 91 firebird v6, had an oil leak for years, got it fixed it was the oil filter, then I noticed my oil pressure went through the roof! The guage stayed maxed at 80. Then after changing the spark plugs, my problems started. It wont idle well, or when giving it gas the rpm's slowly go down till it dies. Changed the fuel filter, ign. Module, distributor, rotor, fuel pump relay, plugs and wires. No change. Messing with the fuel pump or injectors will be my last resort, as it was running fine before this. This bothers me-- when turning the key on "Before starting the car" the oil pressure gauge goes all the way to 80 without the car running? Could the oil pump switch cut off have anything to do with my problems? Thanks for any help. Tracey
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Tray Boy
July 27, 2011.




Shouldn't be any oil pressure without the engine running. Maybe a problem with the sending unit--gage or wiring circuit. Use an analog gage inplace of sending unit, just to double check oil pressure.

Use a gage and check fuel pressure. Any applicable mil codes? You can check those yourself.


JDL
Jul 27, 2011.
Thanks, you talking about an oil sending unit? I can't find anything like that at the auto store? To check my fuel pressure, I'm pretty sure I have to remove the entire manifold, also to get to the injectors and the valve. Not good. Mainly focused on the crazy oil gauge. When it runs for a bit, It will drop to around 60 before it dies. Im not an experienced mechanic, lol


Tiny
Tray Boy
Jul 27, 2011.
The oil pressure switch is N7 in the diagram. If mfi should be a schrader valve on the fuel rail, I'll see if I can find a picture.

Do you know how to check for applicable codes?


JDL
Jul 27, 2011.
No sir, I'm learning by doing. There has been no computer hooked up to this car. I would love a pic of where the fuel valve tester is! I do know where the oil pump switches are, is the oil pressure switch different? Is that what sends the signal to my dashboard gauge? Thanks for the help!


Tiny
Tray Boy
Jul 27, 2011.
My bad, they are called pressure switches, not pump. I know theres 2 of them, one has something to do with cutting the fuel off. Its located right by the oil filter I changed.


Tiny
Tray Boy
Jul 27, 2011.
As far as the oil pressure switch, it handles both, oil pressure gage and redundant power supply to the pump.

To check for mil codes, you use a jumper wire between the A & B terminals at the datalink connector. Then, turn the key, just till the dash lites come on, no further, no crank. The mil on the dash should start flashing, you count the flashes to get the codes. Your looking for two digit codes. An example, code 12 would be 1 flash a slight pause then two quick flashes. May flash three times before moving to next code, if there are any others?

The data link connector should be lower edge of dash, driver side. The picture is just to show location of A and B.


JDL
Jul 27, 2011.
OK! Much thanks! Assuming a jumper cable is just a plain straight piece of wire, I will try this, and I sure think the fuel oil pressure switch may be my problem. If I don't blow me or the car up, I will get back to ya. Thanks so much!
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Tiny
Tray Boy
Jul 27, 2011.
Use a piece of automotive wiring at data link connector or a paper clip. A small piece of wire usually works best for me. Not a jumper cable.


JDL
Jul 27, 2011.
Okay, , appears to be flashing 12 over and over again. One flash, then 2 quick ones, then pauses and repeats. Going to try to look this up in case I don't hear from you for a while, and Thank You for the tip!


Tiny
Tray Boy
Jul 28, 2011.
Code 12 should mean diagnostic mode. If no codes after that, you don't have any codes. You always have the code 12 first.

As far as the oil pressure switch, my database seems to show something different than your post? Databases are not always correct.


JDL
Jul 28, 2011.

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