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A true no-start mystery...


hambone's Avatar
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08-05-04, 09:11 PM   #1  
hambone
A true no-start mystery...

Give this one a try...it has baffled many:

I have a '94 S-10 Blazer (85,000 miles). Recently, it has been giving me problems starting. In the mornings or after long periods of time of not being on, the engine starts normally. Even after I start the engine, drive it around and get it nice and hot, I can shut it off and start it again with no problem (up to even an hour afterward, there's no problem).

However, from about an hour and a half to about six hours later, she'll crank fine but won't turn over. On the third try, she may start to turn over, shudder a bit, and then either start or die (giving it some gas helps the engine to pull out of the shudder).

Once started, the car always seems to run just like normal. A mechanic told me it may have been my Idle Air Control (IAC), so I got a brand new one installed...but no improvement. Is there a brave soul out there with the answer?

 
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08-05-04, 10:06 PM   #2  
is this a 4.3 vortec or is it throttle body injected?
I would suspect fuel pressure problem especially if it is the vortec as it requires 55 psi to start a cold engine if it is slow to build pressure and it has anything less than 55 psi it will not want to start.
have you changed the fuel filter lately.

 
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08-06-04, 03:45 AM   #3  
I don't know where he got the IAC idea but that never had a chance. It has absolutely nothing to do with starting.
Bejay may be on the right track with the fuel pressure but you have to approach this systematically like any other diagnosis. You need to test three things at the time it won't start.
1) good spark at the plug
2) Injecter pulse using a noid light
3) Correct fuel pressure
The correct symptom will lead you to the correct answer.

 
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08-06-04, 08:54 PM   #4  
hambone
Do you all know of a good link for information on testing the fuel pressure. I did plan on changing the fuel filter tomorrow anyway (I believe it's been a while).

Let's say the fuel pressure is low (that makes the most sense with the symptoms), couldn't it be a number possible leak locations? Any ideas on tracking down the culprit?

Thanks for your expert help!

 
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08-07-04, 03:46 AM   #5  
Posted By: hambone Let's say the fuel pressure is low (that makes the most sense with the symptoms), couldn't it be a number possible leak locations? Any ideas on tracking down the culprit?

Thanks for your expert help!
Only 3 possible causes of low fuel pressure.
1) bad pump, includes poss. restricted pick up (most likely)
2) restricted filter
3) bad regulator

 
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