Stephenms

Hey there everyone! Having another issue with the Vette.

I have a 1987 corvette auto and I've been having rough starts this week. Fuel pressure checks out A-okay. 50 psi once relay kicks in and starter works it's *** off to get the engine running. I did replace spark plugs three weeks ago even though a loose plug wouldn't cause this much of a bad start. It's rare that it'll start right up. It used to be 50/50 but now it'll take a few tries to turn on. I'm really stumped on what else this could be. Obviously it's not fuel, unless the fuel pump is bad but seeing as the fuel pump relay jumps the pressure to 50 before start up it almost trials that one out. Once it does start it's at a very very low RPM and sounds like it's starving for fuel which made me think it could be a fuel pump in the first place. I notice more and more the smell of fuel in the interior. The fuel pressure gauge did leak because I had installed it incorrectly so that smell could just be old fuel burning off.

I just disconnected injectors #1, 3, and 6 and saw no change in idle. Bad injectors is a possibility I assume. Also when I disconnected those injectors they still had the injector "pulse/vibrate" when I touched them. Injector 1 was rougher then the rest.

If anyone has had this problem before please let me know and how you're going about fixing it. It WILL start, just needs a few cranks.

Stephenms

After further testing I found that my fuel pressure regulator is bad. Fuel is ejected out of the regulator whenever the car is shut off. Obviously that shouldn't happen. The vacuum line that is connected to it gets a good dose of fuel every time. When I took off that vacuum line I got better fuel pressure and no change in idle. Perhaps I found my problem?

DanielRicany

You indeed did. 50 PSI is way too much for a factory FPR.

Change it and you should be good to go.

And it's hard to tell a power balance test on these cars because they run so smooth.

My 85 with a flat tappet zz409 cam is basically no difference with any of them.

Gotta listen closely.

Stephenms

Okay awesome. I'll be replacing it hopefully tomorrow. Is there a special tool I need? I noticed the screws on the regulator are torx but they have a small dot in the middle. Can I use my normal torx set?

DanielRicany

No, you will need to purchase a security torx set.

Stephenms

Okay, no big deal. My local hardware store should have a set. Is there anything else I should know before replacing the pressure regulator? Anything to keep an eye out for?

Also. I had my plenum/intake apart about three to six months ago to replace a temperature sensor, I did replace the runner gaskets. Do I have to replace them again since I'll be removing the intake again?

DanielRicany

If you're removing the intake, I would replace them just to be on the safe side. Is it worth the risk to have to take it apart all over again after you get a vacuum leak? I don't think so.

I can't answer anything to look out for on that particular repair because I have never removed the stock FPR. I switched to a Miniram intake so someone else will have to cover that question for you.