I-6 hard starting.... - Chevy TrailBlazer, TrailBlazer SS and GMC Envoy Forum



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Go Back   Chevy TrailBlazer, TrailBlazer SS and GMC Envoy Forum > 2002 - 2009 TrailBlazer/Envoy Tech > 02-09 Vortec 4.2L I-6 Engine and Drivetrain

02-09 Vortec 4.2L I-6 Engine and Drivetrain Q&A forum for engine and drivetrain repairs/modifications/tuning.

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  #1  
Old 03-28-2009, 06:23 PM
wheelhorse76 wheelhorse76 is offline
 
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I-6 hard starting....

Have a 2002 Trailblazer 4.2L I-6 . The thing is acting wierd . You have to turn the ignition key on till the fuel pump stops running , and do it again... then it will start. Sometimes it will take 3 times .It will just crank away if you just get in it and try to start . no matter position of gas pedal it does not change anything ?? Where should I start
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  #2  
Old 03-28-2009, 07:06 PM
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Super 88 Super 88 is offline
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Have you changed the fuel filter recently?

If it's not that I would say maybe the fuel pump is on it's way out - or you have a very leaky fuel injector that is causing the system to lose pressure.

Any other driveability problems? Rough idle, hesitation, etc? Any dash lights on?
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Old 03-28-2009, 07:24 PM
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with all suggestions.
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  #4  
Old 03-29-2009, 12:17 AM
wheelhorse76 wheelhorse76 is offline
 
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Fuel filter was cahnged 30 days ago , after starting the thing runs just fine . Fuel Pump ? ... i was always under impression that those either run or they dont
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  #5  
Old 03-29-2009, 12:22 AM
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Might you have to reset the PCM calibration?

Hold off until someone else agrees, but you might have to disconnect both negative and positive battery cables for at least 30 minutes, while these minutes are ticking away, clean the throttle body plate...
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Old 03-29-2009, 12:31 AM
jackedupcanyon jackedupcanyon is offline
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Yes clean the throttle body. Not sure if you have MAF sensor or not but I would clean it also with MAF cleaner if you do. Probably want to change the plugs also. Put in some Iridiums. Might even want to try so really good entire fuel system cleaner.
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Old 03-29-2009, 01:06 AM
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Quote:
Originally Posted by wheelhorse76 View Post
Fuel filter was cahnged 30 days ago , after starting the thing runs just fine . Fuel Pump ? ... i was always under impression that those either run or they dont
Sometimes that is true, but not always. I have seen cases where the pump wasn't putting out enough pressure. I've seen pumps that would work for about 10 - 15 minutes and then quit, after cooling down would work for a few more minutes.

I would agree, it wouldn't hurt to disconnect the battery terminals for 30 minutes and try that - but I don't think it will help. But you never know. It's cheap and easy.
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Old 03-29-2009, 01:19 AM
WOOLUF1952 WOOLUF1952 is offline
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Just disconnect the negative cable. You don't need to disconnect both.
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Old 03-29-2009, 09:17 AM
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Reseting the PCM will not fix a no start/hard start problem.

Reseting the PCM simply reinstalls the factory parms. When this problem is fixed, the PCM should be reset to remove "learned" driving characteristics that may not be correct because of the fault.
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Old 03-29-2009, 09:43 AM
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Don't think the filter would do that, the pump still only makes so much pressure. This sounds like either a fuel pressure regulator or bad fuel pump. The '02 models use an external fuel filter and its on the pressure side of the pump....possible an intake sock or pickup issue, but not the filter. Now if he had no high speed power or fuel starving, yes the filter, but from what he's describing, I don't think so.

Where do you live, can you fill out the profile? There was an issue with '02-'03 (maybe even newer) model years, that involved salt corrosion and damage to the pump/regulator housing. If you're in the salt belt, there's an extended warranty in effect to replace a failed fuel pump.
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