Questions and Answers

Crazy Oil Pressure

Q. My wife's '92 Pontiac Grand Prix has been experiencing a fluctuating oil gage for some time now. It will peg itself at the high end of the gage under normal driving conditions and when you remove your foot from the accelerator it will drop down to below 40 lbs. When you put your foot back on the accelerator it jumps back up and pegs it's self again. It also seems to move around so you really don't know what the pressure is at.

1992 Pontiac Grand Prix
V6 - 3.1
4 speed automatic
102,000
Fuel Injection

Thank you, Chuck

A. Well Chuck, there are three possibilities here. A bad dash gauge, a bad Oil Pressure Sending unit or a bad oil pump. I don't think it's the oil pump. The only way to check this out properly is to remove the OPS and install an outside oil pressure gauge. This will tell you what the actual oil pressure is. If the reading is normal and steady, then the pump is in good shape. Since you have the OPS out, install a new one. That is what's most likely wrong. If the dash gauge still goes nuts, then you'll need to replace the dash gauge.