I am troubleshooting a problem with the oil pressure gauge in my six conversion. It is a 3.0l engine. Since startup of the engine, once the gauge was connected to the sending unit the needle just pegs to the top. See picture. We changed out the sending unit. We also tested the actual pressure with a manual gauge and the pressure is good in the engine. Maybe the gauge is bad? Should I take it over to Palo Alto Speedo for testing?

Is it possible to test the gauge myself, if so, how? Thanks.

By the way, I do have the correct sending unit for the specific gauge.

I believe the stock sender is a variable resistor. So measure the resistance from the sender wire to ground, and see if it changes with engine RPM and such.

If it reads open circuit, or a dead short, you have a wiring problem.

I would bet on a wiring problem, myself.

--DD