1tubecut.jpg	beforecut.jpg	tubescut.jpg

The "Harpoon" Mod (named after TheDieselstop.com user Maroon Harpoon) is done to speed up the filling process on 99+ Superduties. The actual mod is to cut the vent tube that protrudes into the tank. This allows the tank to fill farther before the fuel reaches the vent tube and the filling process becomes agonizing slow. This is especially needed if you use the "High Flow" diesel pumps at truck stops.

Run your fuel tank as low as possible without running out of fuel. This makes it easier to work inside the tank and also makes it lighter if you decide to drop the tank -vs- removing the bed.

Either drop the tank or remove your bed. Removing the bed is suprisingly easy, and in fact may be the better way of accessing the tank. To drop the tank requires you to have a set of Air Conditioning and Fuel Line Quick Disconnect tools. These are cheap and available at all auto stores.

To drop the tank, remove the skid plate (if equipped), place a jack under the tank to hold it while you unbolt the tank straps. While lowering the tank, you will need the Quick Disconnect tools to remove two fuel lines. Unplug the sending unit connector, and unclamp the fill tube from the filler neck. Lastly there should an equalizer tube at each end of the tank that runs thru the frame. Just pull it off.

Once the tank is on the ground, remove the large locking ring that holds the sending unit into the tank. Make sure to use a grease pen to mark the lock ring and sending unit orientation for later. Carefully remove the sending unit so as not to damage it. Look inside and you should see a yellow tube and a grey tube sticking about 6 inches into the tank. Cut these off with a ratcheting PVC pipe cutter, or heat up a knife with a torch and melt your way thru it. (keep the torch away from the tank, safety first). The yellow tube is the actual vent tube. The grey tube is the fill tube and can be left alone, or cut off. I chose to cut mine off.

Re-install the sending unit and pay attention to the orientation, there is a locating groove that the sending unit must fit into before installing the lock ring. You did mark it with a greasepen earlier right?

Reinstall the tank opposite of removal. Run to the fuel station and watch how lightning fast your tank fills to the TOP!

Back to MAIN page