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

starting issues

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Old Mar 23, 2004 | 12:42 AM
  #1  
93formula's Avatar
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need help starting issues

this only happens when its hot, and even then only once in a while.

the car is a 94 formula

when trying to start it doesnt want to fire, the starter is turning it but it wont fire. the opti, and plugs are brand new.

if it fires up it dies right away, it will do this four or five times untill it finally fires up normally.

if it fires up and is about to die i give it enough gas to idle it at 1500 rpm, anything lower it will want to die. and if i force it to idle it shakes violently, more so if release the clutch pedal while its in neutral.

then after say 20-30 seconds all of a sudden the rpms rise (because my foots on the gas) like it realizes the car is on (so i let off the gas) and it idles smoothly.

i have no explanation for this, could it be a bad iac? im new to maf cars so i dont know what could be causing this, some have said bad fuel presure regulator.

never had a problem with a cold start.

Last edited by 93formula; Mar 23, 2004 at 12:59 AM.
Old Mar 23, 2004 | 01:02 AM
  #2  
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A friend of mine had somewhat similer problems, if I remember right all he did was clean the iac and it sloved the problem, I'll have to ask him today.
Old Mar 23, 2004 | 01:04 AM
  #3  
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thanks i too thought it was a iac problem but wasnt sure. please let me know your friends experience.
Old Mar 23, 2004 | 10:27 PM
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anyone else haev any opinions
Old Mar 24, 2004 | 04:57 AM
  #5  
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I would like to have some more information. Even if you have to experiment some with it. ie.....

What happens if it's hot and sits for about 10 minutes? Does it restart ok?

What happens if it's hot and sits for about 2 hours?

Try this the next time the problem occurs.That is as soon as you see the problem, stop cranking the engine and turn the key off. Then turn the key to ON but don't crank the engine. Keep it on for 2 seconds then turn it off. Turn it back on for 2 seconds and then off again. Do this 5 times and then try to start it normally with no throttle. Note the result.

If the power cycling didn't help, try this the next time the problem occurs. Again if it doesn't fire right up, shut it down. Now this time, hold the throttle to the floor and then crank it. Notice if it starts up and idles smoother quicker than when you're having the problem.

All these types of symptoms and cures are indicative of fuel type problems. Some of the above items will indicate too much fuel "dripping" into the engine. While other tests above can determine if you have too little fuel at start up.

One other helpful suggestion is to get a fuel pressure gage, BUT you have a problem. The problem, at least at this point, is it is too intermittent to see. You obviously can't drive around for days with the fuel pressure gage taped to the windshield. Temporary is ok but not for days.

All of the above may not help at all but when you're hunting problems, sometimes you have to eliminate somethings and then go on to the next.

Let us know what happens and we can further help you.
Old Mar 24, 2004 | 05:01 AM
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I agree about a fuel issue..

You can find tests for that as well as other no start tests here but I would start with fuel first

http://mainstreamtopics.com/forum/in...p?showtopic=78
Old Mar 24, 2004 | 08:48 PM
  #7  
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okay , thanks for the input, ill try them step by step. i do have a fuel pressure gauge for a soon to be mine STS turbo system so i guess ill throw it on and see what it reads, thanks!!
Old Mar 24, 2004 | 09:16 PM
  #8  
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oh and the majority of the time it starts fine, this only does it once in a while, say once or twice a week. last week though it did this four times in one day. didnt matter if it sat for two hours or ten minutes.
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