i have a 2000 sierra, and the oil pressure jumps around at idle and smooths out when i give it a little gas, but when the truck is completely off the gauge does not zero out like the rest of them it sticks like 1/4 way. ahs any one gone threw this? is this the sending unit or the cluster im thinking any info is helpful thanks for any advise.

 

Assuming that there are no mechanical issues, and considering that the sender in the block should be out of the loop with the key turned off, I'm going to guess at the gauge in the cluster. Maybe with the key off, go and unplug the oil pressure gauge on the engine to see if it has any effect on the gauge in the cab...if it stays at 1/4, I'd say that the gauge in the cab is at fault. If it then goes down to 0, I suppose the sender or it's wiring could be at fault.

Not sure what mods have been done to the engine, but often when an oil gauge jumps around at low RPM's, there is a problem with the oil pump and/or it's pickup. Pinched oil pump pickup tube o-rings are not uncommon after the oil pump or pickup has been removed for a cam swap with new oil pump, or removing the oil pan, pickup tube, etc to install ARP rod bolts and what not. There are a few different oil pump pickup tube o-rings available, and the green/blue/black ones often don't seal right, but the red one that is available is the way to go...just some extra info for ya that you may not need as I'm guessing that if you've been in the engine for anything that I mentioned, you would have let us know

Gauge failures are not uncommon...they're more common on 04 models, which received and extended warranty from GM, but they can and do fail on all models and years

 

yeahi did a cam swap and put a oil pump while i was at it so yeah that could be a cause thanks for info. am going to diconnect the sending unit and see if the gauge at the cluster is at fault. hope its not the oil pump or pick up or o ring. thanks again man

 

Glad to help man...the incorrect/pinched oil pickup o-ring is very common. The PN for the red o-ring is floating around here somewhere...