A common complaint by builders is that they have problems filling their completed cars with fuel. They have to pump very slow or they risk the problem of over pressuring the tank and get fuel splashed back out the filler.

This problem occurs because of need to cut the Mustang fuel filler pipe to make it fit the Roadster and Coupe. The cutting of the pipe and adding an extension removes the venting feature of the Mustang fuel filler pipe. Lets take a look on how the stock system works.

The system is made up of an outer steel tube which has an attaching ring, an inner rubber tube which contains a rollover value, a flow/vent tube, and a filler/cap adapter. Here is how it works. When you remove the fuel filler cap, you unscrew it from the filler/cap adapter. You insert the fuel nozzle into a hole in the filler/cap adapter. This moves the flapper valve at teh bottom of the filler/cap adapter. When you pull trigger on the fuel nozzle, fuel flows down the flow/vent tube, the inner rubber hose and past the rollover valve and into the tank. As the fuel displaces the air in the tank, it needs to go somewhere. The inner rubber hose is much smaller than the outer steel tube. The space between the two acts as a vent. The air goes up this space and through holes in the flow/vent tube and filler/cap adapter.

When builders modify the Mustang filler pipe, it is the air venting system that they remove. This doesn't allow the air to escape properly when filling thus pressuring the fuel tank. In the modified system, when you stop pumping, the pressure needs to go somewhere and it ends back up the pipe and over the person or the side of the car. I did some research and came up with a different solution.

My solution is to disassemble the fuel pipe and removing all the components. Then modifying the pipe to fit and reinstalling the pieces.

1. Take the 1987-1995 Mustang fuel filler pipe and clean it. Remove and grease or dirt.

2. Locate and drill out all the welds that hold the mounting ring to the pipe. There should be four. I started off by drilling a locating mark with a 1/8 inch drill bit. Just going deep enough to make a dimple. I then used a 5/16 inch drill bit to drill though on the mounting ring welds. Do not drill through the filler pipe.

3. Use a pipe that has a 2-1/4 inch ID and is 1-1/2 2 inches deep to break the drilled welds. I used a piece of 2-1/2 inch exhaust pipe. Place the pipe from the top and pound down until the mounting ring moves down the pipe.

4. Locate the dimple on the filler tube as shown in the following two pictures. It should be in line with where the bronze coloured flapper is mounted in the pipe. Mark a line from the top of the pipe down 3 inches. This is where you will open the pipe to remove the components.

5. Use a 60 grit flapper wheel on a grinder and remove the metal. Go slow and gentle. You can tell if you are going too fast if the metal discolours. Keep going in light grinds checking regularly. When you see the metal start to deform, then you have it very thin. This can also be seen in discolouration even when grinding lightly. When it is this thin, you should be able to use a small pick or nail to open up sections of the pipe. Keep grinding those sections that are thin enough yet, but make sure that you don't touch those sections that are open or you can damage the internal components.

6. Once you have the pipe opened up, mark a line 3 inches from the top of the pipe at the location of the dimple. Then from the dimple mark 90 degrees around the pipe on both sides of the pipe. Take a hack saw and gently cut the pipe.

7. Pry the pipe back. You should be able to remove the filler/cap adapter easily. The use a screwdriver and placing it in the vent hole of the flow/vent pipe, pry the flow/vent pipe and inner rubber hose out of the steel pipe. It will be hard at first, but easier once the rubber tube is past the bend in the steel pipe.

You will now have all the internal pieces removed.

At the 3 inch location where you cut with the hack saw, cut through the pipe. Then you can remove the mounting adapter.

The pipe is 2 inch OD and someone could get a muffler shop to bend the pipe to your exact situation. Then using a muffler tube expander, open the top and put all the pieces back together.

More to follow...