Vapor lock?
Thread Starter
Launching!
Joined: Mar 2002
Posts: 242
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From: Columbia Mo
Vapor lock? Well I hope someone here has seen this. When I bought my 99 WS6 the owner said the only problem she had was that when she used premium gas that sometimes the car would not start and or would die right after it starts, Well I thought she was nuts and run premium anyway, but every once in a while the car will not want to start (seem worse when warmer outside) but if you wait a few minutes it fires right up and runs great. I have swaped out the MAF with the GMS-MAF and added a MTI lid. I get no warning lights and the car seems fine once I get it to start. Any ideas?
thanks you guys are great thats why I ask here first <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" />
Ozz
thanks you guys are great thats why I ask here first <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" />
Ozz
On The Tree
Joined: Apr 2002
Posts: 112
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From: Ottawa, ON
Re: Vapor lock? Hi Oz
My 98 LS1 is doing the same thing. I thought at first it was a fuel problem but after installing and monitoring a fuel pressure gauge it isn't fuel pump related. It is heat related and when the A/C is on the problem is worse. I find it is idle speed related. The engine stalls at very slow idle. If I left foot the brake and right foot the gas to keep the idle speed up the engine seems to stumble badly whenever the A/C compressor and fans start. I'm still working on the problem. If you come across a fix let me know please and I will let you know if I solve it.
Thanks
Neil
My 98 LS1 is doing the same thing. I thought at first it was a fuel problem but after installing and monitoring a fuel pressure gauge it isn't fuel pump related. It is heat related and when the A/C is on the problem is worse. I find it is idle speed related. The engine stalls at very slow idle. If I left foot the brake and right foot the gas to keep the idle speed up the engine seems to stumble badly whenever the A/C compressor and fans start. I'm still working on the problem. If you come across a fix let me know please and I will let you know if I solve it.
Thanks
Neil
Thread Starter
Launching!
Joined: Mar 2002
Posts: 242
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From: Columbia Mo
Re: Vapor lock? Had ATAP running on it and it did it again and ATAP shows a pending code P0108 MAP sensor high voltage, I have posted it but not getting any response from anyone, I sure thought we had more brain power on this site but nobody is chiming in.
I need to get a contact at the dealer and see what they really know about it.
Ozz
I need to get a contact at the dealer and see what they really know about it.
Ozz
Thread Starter
Launching!
Joined: Mar 2002
Posts: 242
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From: Columbia Mo
Re: Vapor lock? Update, it hit 85 degrees today and I was sitting in a drive thru when the car started running VERY bad like it was running on half an engine I pumped the accelerator and all I got was a intake backfire the car was acting like it had no fuel, I was able to pull it out of line and I let it try to idle (maybe 200 RPM) it almost died a couple of times then smoothed out and is running perfect again. ANY IDEAS?
Ozz
Ozz
Thread Starter
Launching!
Joined: Mar 2002
Posts: 242
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From: Columbia Mo
Re: Vapor lock? Those do not really fit the profile here because the problem seem to happen in warmer weather and it has been going on now for a couple of months and 99% of the time it runs great.
<img border="0" title="" alt="[Confused]" src="images/icons/confused.gif" /> <img border="0" title="" alt="[Confused]" src="images/icons/confused.gif" /> <img border="0" title="" alt="[Confused]" src="images/icons/confused.gif" />
Ozz
<img border="0" title="" alt="[Confused]" src="images/icons/confused.gif" /> <img border="0" title="" alt="[Confused]" src="images/icons/confused.gif" /> <img border="0" title="" alt="[Confused]" src="images/icons/confused.gif" />
Ozz
Thread Starter
Launching!
Joined: Mar 2002
Posts: 242
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From: Columbia Mo
Re: Vapor lock? Neil here is what I found, I also put this info on my other post.
I was able to contact someone from GM and he confirmed what I found out on the web lastnight. here is what is recommended. (due to the way my problem comes and goes I am swapping the sensor)
Check vacuum hoses. Check wiring to sensor. Change sensor. Check connections at ECM
I was able to contact someone from GM and he confirmed what I found out on the web lastnight. here is what is recommended. (due to the way my problem comes and goes I am swapping the sensor)
Check vacuum hoses. Check wiring to sensor. Change sensor. Check connections at ECM
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On The Tree
Joined: Apr 2002
Posts: 112
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From: Ottawa, ON
Re: Vapor lock? It makes sense to me as to your problem but I guess mine is different. I have a fuel pressure gauge mounted on the dash and the fuel pressure doesn't drop when the engine stumbles. It actually goes up because the vacuum drops and raises the fuel regulators output pressure (as it is supposed to do). I guess I'll just keep looking. Thanks for the info though. It has been filed.
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Verdad Gallardo Thread Starter
Launching!
Joined: Mar 2002
Posts: 242
Likes: 0
From: Columbia Mo
Re: Vapor lock? Ok I found the problem, it is posted on some other posts, but here is a copy of the fix (AT LONG LAST)
At last the mystery is resolved!!!! All I can say is that if I had not found the problem by accident while taking a long trip this would have gone on forever. The issue was resolved when I pulled the front seat and pulled back the carpet. There is a wiring harness that runs along the drivers door, this harness includes the power for the fuel pump and seats lights and anything past the drivers seat. Just in front of the left front seat bolt is a grounding bolt with 2 grounds attached to it or in my case NEVER tightened. Once I put a ratchet to it all my problems have been resolved. The dieing was because the fuel pump was shutting down and the problem with starting is the pump never turned on till by accident I stepped on the magic spot and the ground was completed. So anyone having the same problems I think we have a fix (several people emailed me with same problem).
Ozz <img border="0" alt="[Fluffy]" title="" src="graemlins/fluffy.gif" />
At last the mystery is resolved!!!! All I can say is that if I had not found the problem by accident while taking a long trip this would have gone on forever. The issue was resolved when I pulled the front seat and pulled back the carpet. There is a wiring harness that runs along the drivers door, this harness includes the power for the fuel pump and seats lights and anything past the drivers seat. Just in front of the left front seat bolt is a grounding bolt with 2 grounds attached to it or in my case NEVER tightened. Once I put a ratchet to it all my problems have been resolved. The dieing was because the fuel pump was shutting down and the problem with starting is the pump never turned on till by accident I stepped on the magic spot and the ground was completed. So anyone having the same problems I think we have a fix (several people emailed me with same problem).
Ozz <img border="0" alt="[Fluffy]" title="" src="graemlins/fluffy.gif" />
