Q: Gas pump thinks empty tank is full and it shuts off

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This happens almost every time I fill up my gas tank. The cut-off on the pump hose thinks the tank is full and it automatically shuts off. What seems to be causing the problem is ‘back up’ in the fill pipe to the tank. Even when the tank is empty, it still happens when I first squeeze the pump’s trigger. Is this a design flaw and is there a solution to fixing this problem?

Yes, this is an issue I have experienced before myself. I had a 2007 FJ cruiser that did the same thing. The fuel filler neck is very narrow on the FJ cruiser and will cause the sense of a full tank at certain gas pumps, especially ones with sensitive nozzles. If this issue happens all of the time, then it is possible that the fuel filler neck itself has become damaged.

The neck runs down from the fuel filler area, behind the rear tire and underneath the back of the vehicle to the tank. There is also a venting tube that runs parallel to the filler neck. Rocks and debris can strike the filler neck and/or vent tube and dent the neck. If this happens, the resulting restriction of the neck or tube will cause fuel nozzles to shut off. New filler neck assemblies can be purchased and installed, but because of the nature of the repair and the safety factors involved, it should be completed by a qualified mechanic.

You may want to enlist the help of a mechanic, such as one from YourMechanic, who will have the equipment and training to inspect and/or replace the fuel filler neck assembly.

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