Erratic Oil Pressure Gauge Reading

[Okie Boarder]

I tend to get a pretty erratic oil pressure reading, especially at low rpm's. The PO said it's done that for a while. The oil levels are good and I don't think there is really a pressure problem, but rather a gauge issue. It causes the beep to occur when this happens and it's annoying. I'm sure this could be the sending unit, the wiring, grounding or the gauge, right? Can anyone give me a logical sequence on what to check in what order?

[knoble]

If you disconnect the wire from the sending unit and ground it it should "bury" the gauge. If this happens then your wire and gauge are fine and you need a need sending unit. Most of the time it is the sending unit that goes bad. You can usually get one at a napa parts store for cheaper than a boat place.

:cool:

[Salty87]

i've had the wire on the sensor work loose and give some erratic readings. otherwise, knoble has it. they're cheap to replace.

[86supraproject]

I can tell you that if you have a gm engine, and they will run at very low oil pressures and be ok. I have seen them run as low as 3lbs for several years.

[Okie Boarder]

I have the PCM (Ford) 351. Where is the oil pressure sending unit located on the engine?

[Salty87]

it's close to the oil filter on 454.

[rickr]

One time I rebuilt an engine due to a bad oil pressure gauge :(
Now whenever I have gauge or oil pressure issues, before I do anything else, I test with a mechanical gauge.

Sensor is front/port of block between oil filter boss and fuel pmp, lt/blue wire.