I turned on the car the other day to check to see if my stereo was working, ran the car for a few seconds then turned it off. About 45 min later I go back outside to find the fuel pump still running. I turn the key to the acc. posision and it shows about 15 lbs. of oil pressure. The car is not running and it should have gone down by then. Is there anything you guys can think of that it could be? The oil pressure unit is new (<2000 miles) I also have a high pressure high volume pump on it.

My theroy is that the pressure is consistantly too high resulting in earily falure of the sending unit even though it's still new. If that is a possibility is there a high pressure sending unit that would work with this? thanks guys for your help.

 

The sending unit for the oil pressure gauge has nothing to do with the fuel pump oil pressure switch. If they're both indicating that there's residual oil pressure somehow, then there probably is.

 

It's on a '91 TPI 350 which has the 3 wire sending unit, I was pretty sure that 2 of those wires sere for the guage and the other was for the fuel pump (or visa versa I can't really remember). There isn't any other oil pressure sensor on the engine so they all have to be contained in the one unit.

 

Camaroguy99, you're right, there's only one oil sender on a 91 and it does control the fuel pump too. As for your problem, try this: next time your fuel pump goes berzerk, unplug the fuel pump relay. If it shuts off when you unplug your relay then the problem is not the oil sender. Since the oil sender bypasses the relay, if the problem were the sender, unplugging the relay wouldn't make a difference. Hope this makes sense.

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91 Z28
Come see The Vicious...

 

that does make sense, next time I have a chance I will try it, but the gauge did show ~15 psi with the engine off. I really think that it is either the sending unit or some how it is only releaving the pressure to 15 psi? I don't know it's late and hopefully I'll have more answers in the morning.