Hey guys I have a 99 gmc sierra and I just dropped in a rebuild 05 LQ9 from gm. I fired it up for the first time and my oil pressure ran about right for 5 minutes and then it spiked off the end of the guage which is over 80. I did change my gauge face so i might not have got my needles back on perfect. So does any one have some advice for me? Were should I start and what should I do? Thanks

 

Turn the key all the way to run position but don't start the engine,the oil gauge should at 0 ,if it moves then the oil sensor is bad.
Engine off - YouTube

 

Ya I did that and it stays right still at 0. So that means it something mechanical and not electrical???

 

Sounds like a bad sending unit to me.

 

Or the stepper motor could have went out

 

/\ These are dead on /\

I have had this happen to me before on my Cherokee and it sucks. It was a pretty straightforward replacement to DIY though; I did it in the parking lot at work because the sending unit actually ruptured and was pumping oil to the ground.

 

But every time i start it, it sweeps from 0 all the way past 80. My best bet still is the sending unit?

 

It may be the stepper motor. Considering that the pressure was fine for the first few minutes, it would be pretty odd for something to fail and cause a pressure spike. I suppose it's possible.

 

i bet its the stepper motor, my fuel an rpm gauge did this

 

I forgot to say that I did change out my oil pressure sensor from my old 5.3 and put it on this new 6.0 because the electrical connector didnt fit the new 6.0 sensor. Would that have messed with it at all?