willysmjeeps.com

The combo oil sender/oil gauge John from Midwest Military sent me is reading strange. It was reading real low, like 20 PSI at startup (I have a rebuilt engine, straight 30W in it) and down to like 15 or less at idle. If I revved the engine, the gauge didn't move. Now it is suddenly reading about 55 at start up, and only dropping minutely at idle. And, when I turn the key, without even starting the engine, it was jumping up to 20 PSI, sometimes 30.
If I hook up a manual gauge to the oil sender port, it reads fine

The only troubleshooting guide you'll find for the 24 volt instruments is here:
http://www.cj3a.info/sibling/milgauge/milgage.htm

In your position with the jeep as your only ride I would just plumb the direct gauge into the dash.

Now, all of a sudden, the oil pressure gauge is reading differently. It reads 15PSI with the ignition on, but the engine off. It's about 55 at startup, and back down to 30 at idle. John from Midwest military sold me a first sender that didn't work at all. He sent me a second one I'm using now. I emailed him, and he said he was sure it was the sender. He'd credit me if I sent it back, but not replace it.

Alright Wes, I used the method on your link, and it's definitely the gauge. It helped me to isolate the fuel gauge too. I thought it was the sender, but it looks like it was the gauge.