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Home » Public Forums » GMCnet » [GMCnet] In tank fuel pumps, or external pumps.
Re: [GMCnet] In tank fuel pumps, or external pumps. [message #316296 is a reply to message #316290] Thu, 20 April 2017 00:14 Go to previous messageGo to previous message
Ken Burton is currently offline  Ken Burton   United States
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
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Senior Member
I have never experienced vapor lock on my GMC with one exception. That was my Onan quit multiple times at 100+ degrees going to GMCMI Branson last summer. Some People here have had problems boiling fuel in the tank on a GMC.

I have experienced vapor lock on a vehicle with in tanks pumps. That was at 100 + degrees in the desert on some no name road with no place to hide out of the sun until the vehicle cooled down. There wasn't a tree anywhere for miles in all directions to hide under. This vehicle has an in tank pump with the output pressure of 55 to 60 PSI. So an in tank pump is not a guarantee of no vapor lock.

After sitting out there in the sun for about an hour with the hood up, the vehicle and fuel cooled down and it restarted. I continued on my way for something like 30 or 40 miles to the next town. There I had lunch at the only restaurant and killed a few hours in town until the sun was almost set. Then I took the car to a self service car wash and cooled down everything under the hood and also the tank with spray water. After that I drove very late into the night (actually a few hundred miles to the next state) to burn off that fuel. I never had another vapor lock problem again. I never removed the gas cap to see if the fuel was boiling inthe tank.

In tank pumps while a better idea, are no guarantee against vapor lock. While killing time in that town, I stopped by the only garage and wrecker service to get his name and phone number in case I got stalled again. He told me that he tows in 3 or 4 cars a week with vapor lock off of that stretch of highway when it is around 100 degrees or better. I did not ask how he knew when to get one of them as there was no cell service out there and only one car passed me in the hour that I sat out there.

Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana

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