I have a 91 camaro rs with a 3.1 liter. The oil pressure drops terribly low and makes the engine shudder like crazy until i hit the gas and bring the pressure back up. Runs fine when accelerator is being pressed. what could be causing this? It has plenty of FRESH oil. just changed it with high mileage 5w-30. No leaks in the engine. I was thinking fuel pump. Anyways, I need quick advice or else i have to drop my baby off at a mechanic which I REALLY don't want to do...

 

Check for a vacuum leak. That would cause a crappy idle and it would probably hesitate a lot. Inspect the vacuum lines, egr, etc. Since your fuel pump is electric revving the engine (and thus demanding more fuel) would only make it worse. So that's probably not it. Are you sure you actually have low oil pressure?

 

Oh crap. meant oil pump not fuel pump. car has 160,000 miles and no one's ever replaced it... Pretty sure no vacuum leak, already replaced all the lines and connections. the idle is hard to measure being that my tach is busted.

 

I just replaced my oil pump. Not that hard, you'll have to lift the engine up a few inches. All you need is a nice tall bottle jack and some wood blocks. Also look at your pan and see if there are any dents in the are of the pump (right before the k-member). Your could also have a clogged pickup screen or your main bearing clearance is too big (ie wore away). If your interested in doing it your self I can give you a step by step.

 

Unfortunately I don't think I have any of the equipment to do it... Well, maybe. I would be interested in a step-by-step if you don't mind.

 

On the 3.1, it has a safety system built in that if the oil pressure is not up to spec, it will shut the relay down to the fuelpump. Its likely that your car is getting ready to stall from lack of fuel tell you push the gas and give it enough oil pressure to satisfy it.

Start with a oil pump from a 3.4 model motor (bigger pickup and tube).

Also replace the timing chain. 6/60 motors recommend replacing them every 30k.

 

Well the timing chain has only been in for about 2k miles. that was loose before. so why wouldn't i get the same size 3.1 liter engine style oil pump? As a side note, the Chevy dealership deemed many of my sensors useless and as a result I have no sensor to indicate air flow in or out... Just in case that may have a bearing on advice

 

The pickup tube on a 3.4 IIRC is .625, where the 3.1 is .5. The screen size as where it picks up is larger IIRC too.

Its been 2+ years since I messed with the 6/60, so I'm going from long term memory.

Good job on the timing chain.

The 3.1 never had a true air flow sensor like the 2.8. And airflow out?? That would be an o2 sensor, and you NEED one of them. That is the key to the whole system.

 

That switch through the oil pressure sending unit to the fuel pump is not a safety feature. It's a backup power source in the event that the fuel pump relay goes bad you wont get stranded. you can take the oil pressure sending unit out of hte block entirely and plug the hole and it would still run just fine.

 

Well, coming from the fact that I ran it for about 1 year without the air flow sensor and about 6 months w/o both i wasn't really concerned. the Chevy dealer told me that it didn't matter and they were the ones that unhooked the O2 sensor (had forgotten the name before).

They also installed the timing chain which was all a total less than $300 for service, parts, etc.

 

Um, NEVER GO THERE AGAIN!!!!!!!!!!!!! You NEED an o2 sensor, period. I'd look to see if they took the bulb out of your SES light because you'll get a trouble code once the car warms up. Gimme a day or two to make a step by step. It's pretty easy. All you need to own is a ratchet set, jack stands, a tall jack, and some 2x4's. You can just rent a torque wrench for free from o'rielly's (i dunno how ta spell it).

 

I'm not sure if they went through the trouble to remove the light. is it separate from the normal check engine light? because that still comes on... but thanks for the help!

 

Check engine light one in the same ses means service engine soon.

 

That's what I thought. They didn't take it out because it still works when something different goes wrong.