When I start my car its around 50,as i drive for a while it slowly drops to 0, only when i rev past 3k does it goes up a TINY bit.

i have full oil...is my pump bad? why would it work for a little? is it the gauge? it takes a few hours before the pressure goes up, restart does nothing only time

 

Could be a bad sender or bad gauge.
Sender is on the back of the block between the firewall and the motor. It is a large cylinder looking thing, should be goldish in color. New sender is about $12 or so.

 

On my car, I don't have the sender in that location. Mine is a black cylindrical thing perpendicular to the block. It is mounted in the oil filter area.

 

It's most likely not my pump though right? It wouldn't make sense that the pump woul work at start and then just stop since it' s mechanical.....why does the sensor work then slowly degrade as I driv? I'll check the sensor.....thanks for the info

 

yea that sounds like its it.... Mine did the same thing and it was the sender..that thing gave me alittle trouble to get out with how its angled and near the block. Definitly doable though. Good Luck.

 

My other car had a bad sender and it lost pressure at hot idle too. If you hear the rattling of the valvetrain, stop the car immediately.

 

I am not sure when they changed the sender location, might have been 87 when they went to roller motors.
My 86 305 and my 95 LT1 has it on the block behind the intake.
A friends 88 GTA has it next to the oil filter.

I'd get a mechanical gauge and double check the pressure.

 

As long as the motor doesn't start to rattle the pump is fine. These senders are real bad about going out...the diapraghm tends to get little holes in it from the heat. Oil leaks through the diapraghm and after a little while it will equalize the pressure on both sides which causes your gauge to read 0 psi. Sometiems they blow out completely and the gauge just stays at 0 all the time.

 

If you were really getting 0 psi, you would not be talking to us. You'd be getting a new motor. I suspect the pressure is equalizing due to the hole mentioned because it reads fine then drops off. Change the sender and you will be fine.

 

it s probably a bad sending unit mine is always peged at the top of ym guage so i wouldnt worry about it!