[jimdman]

Ok so here's the deal. Drove 500 miles each way to Kentucky this past weekend pulling a 7000lb enclosed car trailer and had to fill up while traveling each way. When I bought the truck the fuel gauge wasn't working right from the get go. I filled up in MD and left. I had driven 250 miles and then tried to fill up again. The pump clicked off at 15 gallons. I had to force fuel in to get to 24 gallons with it coming up the filler neck. On the way home yesterday while driving another 250ish miles I went to fill up and it clicked of at 12 gallons. I was like WTF. I pushed another 8 gallons in.

So basically my problem is I know the tank only had a few gallons in it and it was clicking off and back filling up the neck with way under the tank limit.

What's my problem.


Thanks

 

[SandawgK5]

Tank design. Do a search for Harpoon Mod it will tell you everything.

Basically the fuel foams and the vent line causes it to back up the neck. Cut the vent line off inside the tank and the problem goes away.

Dik

 

[GregsSD]

Yes, the Harpoon Mod will take care of the problem you are having!!!

Here is a pic of the factory vent and fill tubes sticking down inside the fuel tank:

What you need to do is to remove your sending unit so that you can get access to the inside of your tank, then use a pair of PVC cutters to cut the vent tube (yellow tube) as close to the top of the tank as you can.
When filling, as soon as the fuel level reaches the vent tube it causes the nozzle to click off, so after cutting it the fuel level will almost reach the top of the tank before it causes the nozzle to click off

Here is a pic of it after cutting it off:

It is one of the best mods you can do to your Superduty!!!

 

[jimdman]

My fuel gauge is also screwed up. Do you think it is the sending unit?

 

[GregsSD]

My fuel gauge is also screwed up. Do you think it is the sending unit?

It most likely is the sending unit or a bad wiring connection going to the sending unit.