'94 XLT very rough starting...

[motopsycho650]

This issue just recently started. The problem is, this is a very intermittent problem.

If the vehicle sits for more than 4 hours or so, sometimes it has a very hard time starting. I hear the fuel pump kick on, but then the engine runs very rough, the RPM's bouncing way down around 300. Sometimes it's a challenge to keep it running. After about 5 minutes, it clears up and runs great.

I knew it wouldn't fix it, but I changed the fuel filter, and it seems I got a slight improvement. Again, the problem doesn't always happen. Also, it's not throwing any kind of code.

Any ideas? I'm planning to swap fuel pumps with a donor part I have saved from my older '92. Other than that, all I can think about is the intake manifold gaskets possibly leaking. That doesn't seem right, because it runs too good once it cleans it's self out.

 

[motopsycho650]

Then, I have weird days that is starts just fine. Today is a cold, rainy morning. I turned the key on, allowed the fuel pump to cycle, and it started right up without any bogging or choking.

I read in a different post to clean/replace the IAC. My brain is not working right now, and I'm not understanding what the IAC is. I'll probably say duh to myself when someone reply's.

 

[MrShorty]

IAC=Idle Air Control valve -- that "film cannister" (if we can still remember what a 35 mm film cannister looks like) thing on the side of the intake manifold.

Have you ever checked fuel pressure? With mine in particular, just because the pump runs doesn't mean it is generating enough pressure. One of the first things I'd probably do with a hard start would be to check the fuel pressure.

 

[Maniak]

Your fuel pressure may be bleeding down too.. Try this..

Turn the key to on and wait for the fuel pump to turn off, then off, then on until the fuel pump turns off, then off, then on until the fuel pump turns off and then start the vehicle..

Do it for a few days.. If it never has the issue during those days your fuel pressure is releasing.. which can be the fuel pressure regulator, an injector or even the check valve on the fuel pump.

edit: if you have a fuel pressure tester, just test the fuel pressure right before you start the vehicle.. that a quicker test.. what I gave above is for the people that don't have a tester.

~Mark

 

[YBCold]

i have a similar issue. i just turn my key on and off twice and usally it runs good

also maybe try cleaning your IAC and MAF sensor.

and also check your fuel filter too. and your air filter

 

[motopsycho650]

IAC=Idle Air Control valve -- that "film cannister" (if we can still remember what a 35 mm film cannister looks like) thing on the side of the intake manifold.

Have you ever checked fuel pressure? With mine in particular, just because the pump runs doesn't mean it is generating enough pressure. One of the first things I'd probably do with a hard start would be to check the fuel pressure.

DUH! I knew I'd say that. I have tried checking fuel pressure a few times, but sure enough, it didn't act up any of the times I tried. I agree that it seems like a fuel issue to me. I have a much newer fuel pump that I took out of my old '92. And, I have the fuel rail and pressure regulator from it as well. I'll try swapping and cleaning parts this weekend.