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Discussion Starter · #1 ·
I want to see if anyone has ran up against this problem. My car sat for a long time with E85 in the tank. When I fired it up all was good. All of a sudden on hot days my gas tank will build so much pressure it will push gas out of the full tube. And run down the quarter panel. I have no check engine codes. It does have full Fore fuel system if that makes a difference. Thanks for any help given.
 

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Reads as if the fuel tank is not venting properly. Does such occur while the car is sitting or running?
 

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Discussion Starter · #3 ·
Reads as if the fuel tank is not venting properly. Does such occur while the car is sitting or running?
Seems to do it either way as long as it is hot out. When you remove the cap you can hear and feel Hot air moving and if you try to add fuel it will spit it back out for sure. It is making noise well after the lid is removed as well not just like letting it out in one big burst. Very hard to explain now that I am typing. I thought not venting properly as well but I am unsure what could have changed as it was working well at one time.
 

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Make sure Eng is NOT running when adding fuel as vent valve is sealed shut when running at idle unless it does its self test. sure sounds like vent valve/cannister or hoses are restricted but will eventually set a P0446 code which is a B code that will not turn on cel until it fails 2 times in a row depending on when it does its test. with a capable scanner you can go into failure records and see the pressures when the first code set
 

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I had a similar issue a couple of years ago with my Firebird and narrowed it down to the vent valve solenoid. Then the problem gradually went away of its own accord. No problems during this very long, very hot summer here in Kansas. Hoping the same for you. Not sure about the G8, but on a 4th gen F-body, it means dropping the tank to replace it.
 

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Discussion Starter · #7 ·
Yes same I believe on G8. I am so confused with this one because I truly feel like it is a case where the fuel is being boiled rather than a vent issue. I located my regulator in the engine bay so I am wondering if the under hood temps caused by engine, Long Tubes, LSA, fuel lines running down tunnel area even though they are behind the heat shields, etc are overheating the fuel and causing it to boil. Really at a loss as there is no codes represented in a full scan of all modules. One would believe that if it were a true pressure situation it would send some sort of response. Maybe I am giving the system too much credit. Also the problem only being apparent during hot days or lots of in town driving leads me to follow the boiling thing. It is weird because when the cap is off and you are hearing the sound from within the tank the air coming out of the neck is very hot. I am lost but hate to have the tank out to find out that I am chasing the wrong type of issue. I guess the old girl is a fair weather car for now. Side note I am not noticing any loss of enrichment at the wideband during these times either. Thank you for the reply.
 

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To see if it makes any difference you could unhook the line from the purge valve before filling up to see if does any better. If you leave it unhooked it will of course give a large evap leak code, but you could pop it off for a fill up and see if its able to vent then or not.
 
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