Gas pump thinks empty tank is full and it shuts off

ANSWER : 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.

ANSWER : The most common cause of this type of problem is when the fuel filler neck’s inner tube comes off of the neck itself. You will need to have the filler neck removed to check to see if the inner tube was knocked off from someone trying to get fuel out of tank with a siphon hose and managed to knock the hose off. This causes the tank to not get filled properly and the inner hose can get caught in the fuel sender causing wrong readings.

If you’d like to get this fixed, consider YourMechanic, as a certified technician can help you service your fuel filler neck and ensure that your fuel gauge functions normally. Good luck.

ANSWER : There are a lot of things that can cause what you’ve described: a faulty fuel sending unit in the tank and the tank is actually full, a stick ORVR valve not allowing pressure in the tank to leave when fueling, or a saturated charcoal canister that cannot let the excess pressure in the tank escape. Are you able to fill an additional $10 in fuel after it cuts off? If so, then this may be a malfunction in the evaporative emission system not allowing pressure to leave the fuel tank when filling. If it cannot take more than $10 at all, then the fuel tank may be full and the sending unit is failing and providing a false reading. I strongly suggest acquiring a qualified technician to perform an inspection due to the volatility of fuel. A certified professional from YourMechanic can come to your car’s location to inspect the fuel problem and advise you on repairs.

ANSWER : To drop the fuel tank on your model, and immediately re-install the tank (without any cleaning or service) would require about 2 to 3 hours in total for an experienced professional if a lift is available. The fuel pump itself can be installed without removing the tank but to do that you must have access to the inside of the car because the pump is removed through an access panel under the rear seat. Also, you can’t drop the tank without access to the inside of the car because to drop the tank the wiring harness has to be disconnected and that connection is only accessible from inside the car. So, if the car was locked, obviously no work was performed on the vehicle. YourMechanic does offer these services and you can start by requesting fuel pump replacement. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.

ANSWER : It sounds like you put in an incorrect sending unit or it is defective and needs a replacement. The fuel sending unit will vary resistance from low to high resistance controlling the gauge. If the signal from the sending unit is opposite of what it should be then the gauge will work opposite of the way it should. I would recommend replacing the sending unit and make sure the new one works opposite of the one you have now. You may have to get the correct one from the dealer since sometimes the aftermarket ones do not always work. You can connect the sender and check it before installing it back in the tank.

ANSWER : Hey there, thanks for writing in about your 1996 Chevrolet Blazer. If you hear the pump, but still get no fuel out of the pump, then you have the power and ground backwards in the wiring or they have it backwards on the pump. If you need help having this checked, a certified professional from YourMechanic can inspect the starting issue and let you know what repairs are necessary.

ANSWER : It sounds like the fuel level sensor on your vehicle is faulty. The fuel level is always about a quarter tank lower than what the gauge says. This can cause the vehicle to run out of fuel when the gauge still reads 1/4 tank. I would recommend having your fuel level sensor inspected to determine if it is functioning properly. If not, have it replaced as soon as possible to avoid being stuck on the side of the road from running out of fuel.

ANSWER : This is a problem likely related to your fuel tank sending unit. This is a small float type component inside your fuel tank that measures the level of the fuel inside the tank. As the fuel level drops, the float level changes and sends a signal to the car’s computer which then displays the reading on the fuel gauge in your dash. If you need assistance with this, I would recommend having an expert from YourMechanic come to your location to diagnose the issue and repair your fuel sending unit as necessary.