Stock Oil Pressure Gauge Question

[RussFEST]

Hey Guys,

Im having a prob with my daily driver/ tow rig, 90 GMC heavy half ton. When I first rebuilt my 5.7 the stock oil pressure gauge worked fine (analog type on LH side), then it dropped halfway across the gauge after a month, and the red 'check gauges' light kept coming on when I was at say a red light. I hooked up a mech gauge and the pressure was still fine, 30-35 pounds warm at idle. I changed the oil pressure sensor on the engine with an aftermarket one, and it made no difference, so I put a GM one in, same again. Fast forward to today (two years later, yes yes I know lazy ass), I finally got mad at it due to other problems and decided to look into it. I was told to check the plug in at the back of the dash cluster, and when I removed it, it looks fine? No corrosion and it was in tight.

What else could it be? The wiring all looks ok to me, but with all the other junk in there I didnt follow it all the way. Is there something else I could check?

This all came about because now at red lights when Im waiting, the vehicle stalls. When the red light comes on, the engine surges/stutters, and every little bit it stalls. Its probably something else, but I wanted to sort this before moving on to something else, as my thinking was the ECM might be taking the low oil pressure literally and try to compensate.

Thanks for looking and any help you may have.

Russ

[My88TexasTruck]

Could be the guage itself. Also, I think I have read in other threads that the ECM will not pulse the injectors if it does not sense oil pressure - so even though you have oil pressure mecanically, it may not be getting the signal electrically. Check for a bad wire, connector or even the sender. Maybe you have 2 senders - one for the guage and one for the ECM? A service manual should tell you.

[derail]

i had an "oil pressure" problem on my 88 5.7 tbi, it was the ecm, it just wasnt registering. therefore it wasnt pulsing the injectors. a new ecm is under $200