oil pump or sensor?

[sjbsuperman1425]

Ok, i noticed the past couple days when i hit a certain RPM, the tachometer will sometimes jump erratically as well as the aftermarket oil pressure gauge. i bought the gauge and sending unit used awhile back and when idling or under normal load, it will read fine. This only happens when in boost and heavy load.

my question is, what would a failing oil pump look like on an oil pressure gauge? Im 99.999% sure its a faulty gauge/sending unit but I would like a second opinion on the matter as i've never experienced a failing oil pump and I dont want to be doing 80+mph at 5000rpm's and destroy my engine. thanks for the input.

[boost_boy]

The aftermarket oil pressure gauges and sending units all have their issues at some point. I would change the gauge and sending unit for a different brand to be on the safe side. If you notice that when the car get fully warmed and you are driving hard under load and the oild pressure is going down as you increase load, but then rises as you let-up, then you may want to check the connection of your signal wire from the sending unit. If that is secure change the package to another brand. If your car persists on doing the same thing after you change the gauge, I personally would be pulling the motor for a full inspection of the bottom end.

[sjbsuperman1425]

Yea signal wire was my main thought. I just didn't know if the oil pump failing will cause a specific reading on a pressure gauge or not

[biosehnsucht]

You said the tach also acts erratic - is this the stock tach or another aftermarket gauge?

[sjbsuperman1425]

Stock tach, automated oil pressure gauge

[sjbsuperman1425]

And I check the "autometer" oil pressure sending unit and the stud will keep turning while I tighten the nut for the signal wire. Two days ago I got on it hard and the gauge read correctly. Yesterday, it would drop a little or just drop off to no signal then jump back to 75psi

[TheMAN]

since it's not just one gauge that's acting up, I believe it's some sort of wiring problem

if your oil pump had problems, you would've known a long time ago!

[boost_boy]

As for the tach, beware of crappy grounding of the car and engine as well as its electricals. If the stud keeps turning on the sending unit, there's the culprit for wandering readings.