1993C4LT1

93 LT1, stock. Been desperate trying to figure out a hard starting problem when letting it sit for a while.

​​​​​​So I did a test yesterday just because.

​​​​​​​Key on, engine off, 42 psi. It leaked 10 psi after 10 minutes. Is that good? Or should I look into probable causes?

JimLentz

Sounds like one or more of your injectors has a slow leak which can cause your problem.

C409

..... I would look elsewhere .....

aklim

Clip off the return line hose, pressurize it and see what happens. If it holds pressure, FPR

1993C4LT1

​​​​​​​thank you. And what if it doesn't hold? Fuel pressure is always 42 at key on.

aklim

If it doesn't hold, you have to dig further then. You might have to clamp off the return line, prime it and while priming, clamp off the feed line and see if it holds. If it does, your leak is between the pump and the feed line clamp. If it doesn't, it is the injectors.

That doesn't mean a thing to me that the fuel pressure is always at 42. How do you know that something isn't leaking and the pump is keeping up? Even if we do a WOT run and see it is at 42, it tells us the pump can keep up.

1993C4LT1

I mentioned it's always 42 at key on, because I thought it would eliminate the fuel pump. I hate to sound like a beginner, but what do you mean by clip and clamp? I would assume to get some pliers, and put something over the return and or feed line that won't damage it?

bjankuski

When you say hard starting are you saying when the car is hot or cold. Sitting after it is hot for 1/2 an hour or sitting overnight when the car is cold?

aklim

YES. Damaged fuel lines are bad.

http://www.sears.com/craftsman-hose-...B&gclsrc=aw.ds

1993C4LT1

anything above 30 minutes sitting, with the engine warm, it's hard starting. It always fires up perfect on cold starts. To make it simple, anytime the engine has been ran for a period of time, it's hard starting. But say I shut it off when it starts on a hard start, and attempt to start it, it fires up fast. Am I making sense?

@bjankuski

1993C4LT1

I found this thread, and OP has the exact same problem as me. Even the same bleed down rate. Except my car always passes emissions, and I've had this problem(hard start) since I bought my 93. And I don't have 140k on my car, I have 81k miles. Unfortunately, he didn't say whether he found the problem/fix.

https://www.corvetteforum.com/forums...s-problem.html

C409

..... Key on fuel pressure is the most important pressure there is to a running engine ... why would it matter to your no-start condition if the pressure leaks down a few pounds when the key is off for ten minutes ? .....

1993C4LT1

I hear you. Except I don't have a no start condition. I have a hard starting condition when the engine is ran up to temp, and I let it sit for about 30 minutes or more. That is why my fuel pressure matters to me.

SJW

Look elsewhere for the cause of your hot hard start problem. Fuel pressure is not going to be the fault. Does it puff black or blue smoke when it does eventually start up?

Live well,

SJW

bjankuski

More then likely this is a leaking injector problem. When the car is warm it does not need much fuel to start and if you get too much fuel in the cylinders it will flood and be hard to start. Your fuel pressure is fine but the slow drop in pressure combined with the hard warm start tells me that the injectors are leaking into the cylinder and after 1/2 an hour they have leaked enough fuel to make it hard to start. You can check this by flooring the car before you start to crank the car on a hot start and see if the car starts quicker. (obviously let off on the gas as soon as the car starts) If it starts quicker some or all of the injectors are leaking down into the cylinders. Confirm this theory and then decide on the next step.

Sometimes you can pull the intake bellows off the throttle body and hold the throttle wide open and you can actually hear the injectors dripping fuel, it will sound like a very slight hiss.

JimLentz

I had a similar problem on a BMW 6 cylinder and when it started after sitting for a short while it felt like it was running on 5 cylinders. I ran a couple of tankfuls of fuel injection cleaner and that cleared up the issue. The best way to fix it would have been to replace the injectors.

1993C4LT1

I'll give it a try. I wish I could lift the fuel rail, prime it, and inspect for leaks. But with the fic injectors, not possible.

aklim

Why is it not possible with FIC injectors? They are injectors like all others unless you are talking about the fuel injection retainer which they no longer use?

When was the last time it was inspected by FIC?

1993C4LT1

​​​​​​​Yeah because they no longer use the retainers. I have never sent them to him for inspection. I bought these injectors September 2015. It makes sense that they could be leaking. Because on hard starts, it doesn't idle perfect. But will idle perfect after about a minute.

aklim

Send it back and it will be quickly verified if stuff built up in it or not. More than likely, it has.