Join Date: Sep 2006
Location: Longmont, Colorado
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Gas tank gets pressurized?
I am new to the BBS, and it sure looks interesting.
I have a 1984 CJ7 with I6 258 engine. Most trips I run into this problem and would like to find a permanent solution. This has been occuring for several years.
Pressure builds up in the gas tank. The result is eventually a poor running engine that won't idle due to the carburetor flooding. A couple of times I have had gas dripping out of the charcoal canister. There is often, but not always, an altitude increase involved. Home altitude is 5050 feet and I have gone above 11,000 feet. I have also had the pressure develop after 10-15 minutes of idling in my driveway, so maybe the exhaust pipe is heating the gas tank.
My temporary solution is to stop and loosen the gas cap every 20 minutes or 1000 foot elevation gain.
I described this to the local dealer. They said that they "blew out all the lines" and didn't find any problems. They also didn't fix the problem.
I studied auto repair in High School several years before this Jeep was born, but I do enjoy tinkering with it. I know that the fuel system is supposed to be a closed loop to control vapors from polluting the atmosphere, but somewhere there must be a vent to allow for expansion and contraction from heating and fuel useage.
Any ideas will be appreciated.