Twessing

Ive got a 91 camaro rs 3.1l and if i let the car sit for a while it will start right up and idle for a minute maybe. then it shuts right off just as if you were to shut the key off. If you rev the car up it will rev up a little then shut off. I suspected maybe the ICM but i swaped it out and same thing, now if i keep starting the car and let it warm up then the car will begin not starting and will fire a couple times and die imediately. I hooked up a fuel pressure gauge and when you key on it goes to 45 then drops to 40 and holds but slowly drops. over the course of maybe 5 mins it drops to 8psi and wont go any lower. This isnt normal is it? Any ideas what is causing it to shut right off? and what might be causing the pressure to drop, a regulator? a fuel pump?


Any help would be greatly appreciated!
Thanks!

RBob

iTrader: (1)

If the engine still has the stock OEM Multec injectors, replace them.

RBob.

Twessing

Do you think that its leaking through the injectors and thats why after it runs for a bit wont start because its flooded?

Twessing

more suspicion towards bad fuel pump. Today wouldnt really run. would fire then shut down. So i decided to spray right into the TB and it revved right up like it should and then it would shut off once i stopped spraying. Must be the fuel pump doesnt stay running? any other ideas instead of replacing injectors, im on a rather tight budget

RBob

iTrader: (1)

The stock OEM Multec injectors, the coils short out and the ECM can't open them. The result is no fuel to the engine.

Before replacing the fuel pump, borrow a fuel pressure gauge and check the fuel pressure. If low it could also be that the filter is clogged.

RBob.

Stewie

Since your fuel pressure drops so fast, it could also be the fuel pressure regulator (FPR). As RBob noted, if you have the original Multec fuel injectors, they may need to be replaced. The Multec injectors are poor quality and tend to fail quickly.

Your fuel pressure should not drop for at least 20 minutes after shutting off the engine. When you turn on the key, the fuel pump starts up for a few seconds to put fuel pressure in the system then shuts off until you start the engine. I had similar symptoms and found a bad FPR. When replacing the FPR, I also noticed that one of the Multec injectors was leaking and replaced all the injectors. I had about 140,000 miles on the car at that time. I got more miles out of the Multec injectors than a lot of owners.

However, check the easy stuff first. How old is your fuel filter? If you don't know, replace it first. However, based on your description, it is likely to be the FPR and/or injectors. Not too hard to change, but you will need to remove the top of the plenum and replace the top plenum gaskets.

You can get a less expensive FPR online at Rock Auto (www.rockauto.com) and good new or rebuilt injectors at SouthBay (www.southbayfuelinjectors.com). SouthBay will give you a discount if you tell them you are a ThirdGen.org forum member. If you want to save some $$, they have good quality rebuilt injectors. It's best to call SouthBay at 516.442.4707 to make sure you get the right injectors for your vehicle.

Base91

iTrader: (1)

Replace the injectors (Southbay?) and while you're in there replace the diaphragm in the fuel pressure regulator so you won't have to take it all apart to do it when it fails. That way you're working from a good foundation.