how to check oil pressure gauge/sending unit?

[dlb]

the oil pressure gauge in jenn's truck has never worked properly. when the key is turned to accessory the gauge reads about halfway but as soon as the engine starts, the gauge drops to nothing and that's it. how do i check the gauge and sender to determine which one is hooped?

[ARCHINSTL]

I'd imagine the Tercel FSM would work...FSM: LU-2, but BE-27&28 looks easier for a start.
You might also check the AutoZone site and enter your truck; it has pretty good Repair Guides info on most older vehicles.
Tom M.

[Jarf]

DLB - if you are worried about it you could install a manual mechanical gauge in place of the sender to verify actual oil pressure, but if you didn't have any, the engine would be rather noisy.
99% of the time, it is the sender.
The variable output senders ( as opposed to the idiot light type) are notorious for having the internal spring go weak and read low after a time though they usually work fine when the engine is cold.
Back in my Jag days, they actually came out with a "fix" which involved replacing the VO sender with an standard idiot light type and a resistor to create a 1/2 way reading, I think they got tired of replacing sending units under warranty, customers tend to freak when they see no oil pressure displayed.

[dlb]

thanks jarf. i know that the pressure is fine, it's just one of those small details that bugs me and i want to get to eventually. the PO had installed an AM oil pressure gauge but it was ugly, didn't work either, and was totally in the way whenever i needed to remove the dash, so i removed it. i'll get this stock one working at some point.

[arbskynxnex]

http://www.ncttora.com/fsm/

Bunch of toyota 4runner/truck FSM's here, they might have the one you need.

[4wdchico]

I have seen so many bad oil sending units on Japaneese motorcycles and cars that were built in the '70's & thru the end of the '80's that I just replace them as soon a I have any issue. May not be the problem, but at least you will be done with the old one...

Not my usual approach to electrical issues at all. But in this case of the oil senders I have a standing policy.