I'm working on a 96 XJ, when I bought it the oil pressure gauge was pegged at 3:00 o'clock. I found a "good' used gauge, installed it and new sending unit at the same time. Started her up and bang the new gauge shot to 3:00 o'clock and stayed there. Any ideas?

You need to verify the pressure with a mechanical gauge to be certain.

That said, what do you mean by 3 o'clock? Do you mean "all the way to the high side"? If so then that's a common failure with a bad sending unit - but since you replaced the sending unit, I'd start looking at the wires and see if a damaged wire is grounding out somewhere.

The proper oil pressure range is no less than 13psi to no more than 75psi. Typically the pressure should read between 20 (hot idle) to 60-ish (under load).

Pat

Yeah the gauge reads to 80 PSI at about 2:00 o'clock, My needle passes that and is pointing straight right. Yes new sending unit I install with the new gauge. the few inches of the wire I can see look good, guess I have to do some tracing.

Thanks
Frank

+1 especially the wiring. My '96 had the exact same problem.

My money is on the wiring. I bought a new sending unit for mine and it did the same thing. I did the tune up work on the engine: new oil pump, etc., so I knew it didn't have pressure issues and ended up leaving it alone.

I'd do what PatHenry said and make sure you've got good pressure, then get a new sending unit. If that still pegs the needle, it's a wiring issue for sure.

Are there common places to look for wiring problems? My 96 does the same thing(pegged high), and has already had the sender replaced.

Trace the wire up the harness and check for continuity—make sure there's no short in the path. the '96 has single wire.

I don't have a link to a pre-97 wiring diagram, but something like that should help you see where the wire runs.