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Hi, I have an 86 f250 w/460 stick 4wd. Problem is when the :f: tank is full and I am drawing fuel from an almost empty :r: tank and shut the engine off fuel begins being forced out of the f tank through the filler. How the pressure builds up, and how to make it go away. My first thought is change the filler cap the vent mechanism may be snafu. I always think of a soultion that seems most reasonable and cheap and it often turns out to be way different and way more expensive. I look forward to any and all suggestions. THANKS
I have an 86 F-350 that does exactly the same thing. Also, always a lot of pressure in the forward tank when I go to fill up. Also, I can't get more than about 13 gallons into it before it acts like it's "full". Where is the venting system, and how can I fix it?
I don't know if it is the same, but the venting system on my 80 runs under the bed to pick up both tanks, and then runs to the back of the cab where it takes a turn to the passenger side. It then runs along the frame rail to the front where it goes to the charcoal canister.
I have the same problem with the pressure build up in both tanks. It appears that regardless of how much is in the rear tank it still lifts the cap and flows out. Does the charcoal canister act as a fume vent for the tanks? If the canister was blocked, or the line to it was, wouldn't that result in and under-pressure from the vacumm caused by fuel pump suction? This is the opposite of what I'm seeing... I'm confused
[updated:LAST EDITED ON 12-Jul-02 AT 04:15 PM (EST)]In each gas tank is a little vent tube that runs inside the filler hose. It's plastic and goes from the top of each tank and stops at the top of the filler tube, where the cap goes. Make sure each tube is not clogged up. Next tiime you fill up dont fill each tank so full and see then if it still does the same thing.