LT1 Based Engine Tech 1993-1997 LT1/LT4 Engine Related

Help: Cant Figure This Problem Out!

Old Mar 26, 2004 | 09:48 AM
  #1  
Fast96WS6's Avatar
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From: Bergen County, NJ
Exclamation Help: Cant Figure This Problem Out!

I posted a few days ago about my fuel pump starting to go. I'm going to check my FP on sat when I have access to a FP guage. But someone tell me if this could still be a FP problem

My car has had BAD hard starting probs recently when cold. When its raining or had rained, the car will not start at all. Gives a few Put Put's, but wont turn over. UNLESS I swap out my new programmed OBDI PCM with my stock PCM. When I put in my stock PCM, the car still starts hard, but starts up after a while. I ended up draining my battery trying to start it on the new pcm. BUT this only happens when its wet out. Otherwise, it will start with the new PCM but only after a while of cranking.

WHAT CAN THIS BE?

I'm thinking it has somthing to do with the timing being advanced in the new PCM

I already ordered the racetronix FP because its my stock 130K FP, might as well change it anyway

Last edited by Fast96WS6; Mar 26, 2004 at 09:51 AM.
Old Mar 26, 2004 | 09:55 AM
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Untill you test the fuel pressure for correct pressure and no leak down it;s just gonna be a stab in the dark, Start there and see what happens
Old Mar 26, 2004 | 10:04 AM
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valter's Avatar
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Exclamation

I had simular problems with my car. It was fuel pump. Try not to drive far away with these symptomps. Towing is totally sucks, especially when it's not included in your insurance
Old Mar 27, 2004 | 01:39 AM
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The FP is on order, just a few more days.

I took my car to redline tongiht to see how it would do, and it threw an SES code, then the code went away as soon as I was back down in lower rpm's. I'm guessing its running lean up top. I'll check the F Pressure asap.
Old Mar 27, 2004 | 01:44 AM
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I've had two hard start problems. One was the opti pulling its usual crap. The second was my AFPR. The seals inside it were leaking fuel into the vacuum line which was sucking fuel directly into the manifold and throwing the computer outa whack. I put a stock one back on and I'm much happier now (well, I will be when I get the car running again, hopefully this weekend).
Old Mar 27, 2004 | 10:59 AM
  #6  
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Originally posted by 97WS6SCharged
I've had two hard start problems. One was the opti pulling its usual crap. The second was my AFPR. The seals inside it were leaking fuel into the vacuum line which was sucking fuel directly into the manifold and throwing the computer outa whack. I put a stock one back on and I'm much happier now (well, I will be when I get the car running again, hopefully this weekend).
How could I tell if it was the FPR problem you had?
Old Mar 27, 2004 | 11:01 AM
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Pull off the hose that goes to the FPR and cycle the fuel pump a few times. If it starts dripping then that's probably your problem. I found mine when I removed the throttle body and found the inside of the intake wet with gas.

Also, with mine, if you let it sit for a day or so, it would fire right up on the first crank (stock like), but if you let it sit for an hour it would just spin the motor for 10-20 seconds before it caught. Also, as it got worse, I could smell gas when I started the car.

Last edited by 97WS6SCharged; Mar 27, 2004 at 11:03 AM.
Old Mar 27, 2004 | 12:14 PM
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I'll check out the hose you are talking about right now.

Your symptoms seem the opposite of what I have though. Mine cranks right up after letting it sit for an hour, but after about a day, it wont fire up before about 10-20 seconds.

I also just ran a datamaster scan on it while going for a drive. I'm not exactly sure how to read the datamaster file, but I do know that its looking really lean. The code that I threw last night while taking it to redline was MALF 55 - Fuel System Lean. I'm throwing a FP guage on it tom morn when I get access to one.
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