What is a fuel tank filler neck and where is it located?

A fuel tank filler neck is the long tubular part that connects a vehicle's diesel fuel or gas tank to the fuel cap. When you remove you vehicle's fuel cap to fill your tank with gas or diesel fuel, you insert the nozzle from the service station fuel pump into the fuel filler neck. The fuel tank filler tube provides a passageway for the fuel to easily enter into the vehicle's fuel tank, eventually passing through into the engine.

On one end, the fuel filler neck assembly can either be soldered to the actual fuel tank or can be connected by a rubber hose with hose clamps. On the other end where the fuel cap is located, the fuel tank filler neck may bolt to the quarter panel, bumper, rear filler panel, or may just stay suspended from the fuel tank solder.

How do I know my fuel filler neck needs to be replaced?

Many fuel tank filler necks can become rotted or rusted over time, causing them to leak air or fuel. An air leak in the filler neck may cause the check engine light to come on or allow fuel vapors to escape. In many states, this would result in a failed emissions inspection. If your filler neck is leaking fuel, you may notice that your vehicle isn't getting as good fuel mileage as it used to because every time you fill your tank it leaks out of the filler neck tube, meaning less fuel getting to the tank. Even the smallest of holes in a fuel tank filler neck can result in a large amount of fuel loss over time. Leaking fuel is not only a waste of money, but also a potential fire hazard as well. A fuel filler neck assembly may also become bent or distorted from an accident. When any of these things occur, it is time for a replacement as soon as possible.

Can I replace the fuel filler neck myself?

Before beginning the procedure, make sure the fuel level is below the filler neck line. The fuel filler neck can be replaced with a bit of patience, especially if there's rust. Usually a few bolts need to be removed from the tip of the neck and possibly the neck itself. The neck is usually attached to a tube or tubes connected to the gas tank. Loosen the bracket holding the tube to the neck, and then pull the neck down and out.

Reinstalling the neck may take a bit of manuevering, but once its in place attach the tube and bracket back to the neck. Then simply tighten the bolts that hold the neck to the car.