Won't restart when engine is warm

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  #1  
Old 04-07-08, 07:45 AM
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Won't restart when engine is warm

My 1988 Grand Prix 2.8 litre almost left me stranded twice in the past couple off days. I drove it around, went in to the store and then went to restart it and it cranked but wouldn't start. I waited several minutes and it finally started. Since I was by myself, I couldn't verify if it had spark or not. It started fine when the engine was cold all weekend.

I will try to duplicate the problem and then check for spark but if not, does this sound more like a ignition control module, crankshaft position sensor or perhaps fuel injectors that are out of spec.? Any other ideas? Thanks!
 
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  #2  
Old 04-07-08, 08:04 AM
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george...there isn't enough info at this point to offer up a "it's more than likely". 6 injectors failing at once...definately not.

ign modules go bad...so do fuel pumps and engine controllers. you have the right approach...drive it til you get it to act up and then test for spark. and yeah...crank sensors go bad on those as well...but are a huge PIA to replace. lets' try the diagnostic route first...it's usually much cheaper and more satisfying.
 
  #3  
Old 04-07-08, 08:26 AM
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Thanks for the input!

Hopefully I can get it to not start again but only in my garage. The fuel pump was replaced 3 weeks ago. The pump does "energize" when you turn the key to ON when the car wont start.
 
  #4  
Old 04-07-08, 01:15 PM
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just because the pump runs does not mean it has sufficient pressure to start the car you could check for spark first though, if you get the vehicle to act up but if you have spark you should probably check fuel pressure and injector pulse.
would say crank sensor, ecm or fuel pump either one of those could cause your problem.
 
  #5  
Old 04-07-08, 10:33 PM
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A repeated stall after hot restart may be caused by residue accumulating inside the throttle body bore, behind the throttle plate, which limits the air flow past the throttle plate in the idle position. The hesitation concern may be due to a lean electronic control module (ECM) fuel calibration. The cold start stall may be due to a lean ECM calibration, low engine idle speeds, the loss of fuel pressure, or loose electrical connections at the ignition coil and/or the mass airflow sensor. TSB 88-6-97

Check the Oil Level, too. I know back then the 1989 Cavalier Z24 would shut down the fuel pump circuit with low oil pressure. Would store a code for Fuel Pump.

Check for DTC's, can be done with a paper clip.
 
  #6  
Old 04-08-08, 06:13 PM
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I'm going to argue with carguyinva just a little bit and say that all 6 injectors don't have to fail it only takes one out of spec on the resistance to cause a problem because they are wired in parallel.
 
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Old 04-09-08, 04:37 AM
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looking at the wire diagram, the injectors are wired in 2 groups of three, hence there are 2 separate injector drive circuits. one failed injector won't cause a problem in the other 5. in fact, a low resistance condition in 1 injector might cause a QDM to shut down since they are current limiting, but they come right back on as soon as they cool. so a single failed injector wouldn't cause a warm restart issue as the driver would be operating normally until threshold current is reached. there are so many other more likely causes for "hard start after hot soak".
 
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Old 04-09-08, 06:33 AM
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OK.. I drove it around the neighborhood, got it hot, shut it off and tried to restart it. I worked fine. Darn... I tried a few more times and finally git it where it would not restart no matter what! Great. It finally died for good. I checked for spark and got nothing. Fuel pressure was good. I pulled the ignition control module and had it replaced for free under warranty from Autozone. I replaced it last back in 2003.

As far as the injectors going out, I did have a similar issue a couple years ago, where the car would not restart when hot. I pulled the plenum back then and found three injectors that were out of spec. I replaced them and it was fine. The only thing is it was 3 injectors that were bad and the car also stumbled real bad upon acceleration too.
 
  #9  
Old 04-09-08, 07:00 AM
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That's good...i hope that does it for you.

and on the injector thing...while rare, multiple injectors do fail and I guess three lean or rich cyls can keep an engine from starting. I've seen 6 fail once in my time in a 2.8L cavalier. All with shorted coils and a no start condition. the root cause...too much gas line antifreeze. 10 or 12 empty bottles in the back floorboard was the clue. the alcohol in the additive attacked the insulation on the inj coil windings, shorting them out...also trashed the driver circuits in the ECM. sometimes if a little is good...alot is NOT better. never say never in this business...
 
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