How to Replace the Filler Neck on a Ford Truckby Chris Stevenson
A variety of leaks can come from the fuel system in your Ford truck. Cracked or loose hoses show obvious signs of leakage. Sometimes gas tanks corrode and leak at the seams. One other possible source of leaks is the filler neck tube, which extends from the gas cap location down through the quarter panel and into the top side of the gas tank. The filler neck tube suffers a lot of vibration and flex and so can leak from age and deterioration. When the time comes for a new filler neck tube on your Ford truck, a do-it-yourself vehicle owner can perform the replacement in a few steps.
Place the vehicle in park or neutral with the emergency brake set. Disconnect the negative battery cable at the battery post. Use the floor jack to lift the vehicle high enough to place two jack stands under the front frame and two under the rear frame. If you wish to drain the gas tank, find the drain valve and drain the fuel into a large container. If not, run the vehicle until it's nearly dry of fuel. Then you will be able to drop the tank with assistance.
Open the gas cap fuel door and remove the gas cap. Use the appropriate socket to loosen and remove the filler neck's upper mount brackets. You will find the filler tube neck bolted to the inside of the quarter panel just inside the fuel door. On some models, the bracket has Phillips screws, so use a screwdriver to remove them.
Slide under the vehicle and look for any secondary bracket near the tank. Remove the bracket with the correct socket and wrench. If your vehicle has a metal heat shield covering the bottom of the tank, remove it with the correct socket and wrench and set it aside.
Spray penetrating oil on the tank strap bolts. The tank straps look like thin metal bands that stretch from one end of the tank to the other. One end of the straps might have a hinge arrangement, which will require the removal of only two bolts. Ask an assistant to help you gently drop the tank onto the floor. If not enough slack exists for the fuel lines and sensor wires to reach, prop the tank with a floor jack underneath it.
Use a screwdriver to remove the fuel line hose clamp on the fuel inlet line (or pliers if it has spring clamp). Plug the fuel line with a bolt or rag tip to avoid leakage. Remove the electrical wires (fuel pump and sensor) from their connections. Depending upon the model and year truck, the connectors will be either eyelet screws or pull-off spade types. Disconnect the fuel vent hose at the tank. Pull the gas tank from underneath the vehicle into the open.
Grip the base of the filler neck tube firmly. Then twist and pull it free from the gas tank. This procedure must be used for the pressure type fitting. You will see a rubber O-ring on the inside of the gas tank inlet lip. Remove the O-ring and discard it. Wipe the O-ring seat clean with a rag. Remove the large hose clamp on the rubber hose at the base of the filler neck tube. This procedure must be used if the configuration has a flexible hose below the metal portion of the filler neck tube. Disconnect the large hose at both ends if your truck is equipped with one.
Lubricate the new O-ring with grease and place in its groove seat on the tank. Manually push the new filler neck tube into the opening, using enough pressure until it seats firmly. For the rubber hose type configuration, attach the hose (or a new hose if you want it replaced) to the tank inlet neck and then onto the new filler neck tube. Use two new hose clamps and tighten them with a slot screwdriver.
Position the tank under the vehicle. You can use a floor jack with a piece of wood on a spoon to slowly hoist it up in position just high enough to reconnect the fuel line, vent line and the electrical wires. Make sure the fittings have clean and tight connections.
Ask your assistant to raise the tank while you guide the filler neck tube up into its proper position. Make sure the brackets do not snag on anything. While your assistant holds the tank steady, go to the outside of the vehicle and align the top filler neck tube brackets with their holes. Place the mounts screws ( or bolts) into the mounting holes and tighten them firmly.
Slide back underneath the vehicle and align the straps across the tank. Put the tank strap bolts into their holes and use a socket and wrench to tighten them. This will require some coordination between you and your assistant. Replace the heat shield (if removed) and tighten it with the correct socket and wrench.
Add fuel to the tank if you have drained it. Reconnect the negative battery cable. Lower the vehicle from the stands and start the engine. It may take prolonged cranking to start to prime the lines. Once it starts, check for leaks.
- On some Ford model trucks, it is necessary to remove the spare tire and bracket assembly. Check your owner's manual to confirm this before you begin.
- On fuel-injected systems, release the fuel pressure at the fuel rail assembly.
Things You'll Need
- Owner's manual
- Floor jack
- Jack stands
- Filler neck
- Flexible tank hose (if applicable)
- Tub container
- Penetrating oil
- Socket set
- Ratchet wrench
- Combination wrenches
- Hose clamps
- Thin wood plank
- Do not smoke near the fuel tank removable area. Keep the tank away from any flammable source.
Chris Stevenson has been writing since 1988. His automotive vocation has spanned more than 35 years and he authored the auto repair manual "Auto Repair Shams and Scams" in 1990. Stevenson holds a P.D.S Toyota certificate, ASE brake certification, Clean Air Act certification and a California smog license.