Weird gas tank problem


my 1998 Nissen Altima belches gas back when I try to fill the gas tank, can take me 35 to 45 minutes to fill.


I don’t know how your fuel tank vents air but it sounds like whatever the venting system is, it’s either plugged up or not operating correctly. As gas goes into the tank, air must go out to make room for the gas. If the air can’s escape, the gas is going to have major trouble going in, maybe resulting in the belching you refer to.

 Have you been in the habit of topping off the tank as you fill it?  If so, you were the cause of the problem.  Topping off the tank clogs the vent system and the fix is to replace the charcoal canister.  On the other hand it may be a crimped or old hose in the vapor recovery system of your car.  

Good Luck


Most cars today have an “anti-spill roll-over check valve” in the filler neck just below the filler port. It’s a simple floating ball check valve that prevents fuel from leaking out if the car is upside down. Sometimes, when you fill the tank to the top, the ball floats up and sticks in the closed position blocking the filler neck. You can try slipping a small plumbing snake down the filler and try to dislodge the stuck check-ball, or you can remove the filler pipe between the fill port and the tank and remove the ball, which will be a separate part…The vent is seldom the problem. When the cap is off, the tank fumes are free to vent back up the filler pipe, which is large enough (3") to accommodate both fuel and vapor return…


Service station fuel nozzles have the vapor return built in. ///// To the other mechanics, with the engine shut off, HOW are the fuel vapors drawn into the charcoal canister?


I agree with hellokit that one shouldn’t blame the vapor recovery system, not unless proven otherwise. If this were my car I’d poke a stiff wire all the way down, trying to locate or penetrate an obstruction if one existed. I’d also carry my wire at all times, especially to the filling station and try a fill-up with wire inserted. Dunno, but I’m willing to wager a 5-pack (one for me) that this would solve your problem.


Once you have dropped a few gas tanks and discovered the “safety” check-valves in the filler necks, it all becomes clear why you could have trouble filling a fuel tank. It’s just a 2.75" cork ball that can float up into a socket blocking fuel flow…