Archived Fuel leak from top of tank

[Wyomingcowboy]

I have an intermittent fuel leak coming from somewhere on top of the tank. I looked with mirrors and a flasglight but can't see anything obvious. Is there some common problem that I am not aware of? I had the bed off 3 years ago to install the Air Dog but have had NO problems until today. Any Ideas?

 

[Sticks]

Mine does it too when I try to squeeze that last 2 gallons into the tank/filler neck.

Most likely it is either coming out of the vent or sending unit seal.

However if it is a constant leak regardless of fuel level, I would hold the return lines as suspect. The OEM quick connect does have 1 or 2 o-rings in the female side for seal.

There has also been a problem with the steel lines along the frame rail behind the tank getting rubbed through.

 

[GAmes]

The big hold down ring for the canister might be a little loose. If you are flexable enough you can tighten it with a long flat blade screwdriver and a mallet. A few taps will let you know if it is moving.

 

[Wyomingcowboy]

I tried to tighten it and thought I had it only to see it dripping a few minutes later. I park outside at night and temps have been dropping to about +20. I notice the leak when I pull inside the warm shop.

This morning I went ahead and opened the fill cap and I had a vacuum but that seems to have stopped the leak.

 

[JTruelove]

Mine was doing the same. Ended up being the bulk head fitting needing tightening. I used a strap wrenches to tighten. No leaks

 

[Wyomingcowboy]

Do you mean the big deal on top?

 

[JTruelove]

Yes the big thing on top.

 

[Wyomingcowboy]

I pulled into the heated shop again this morning and popped the fill cap and so far so good. It must have been expanding under the heat and forcing it's way out somewhere. I only had a 1/2 tank previously, though. Today I have almost a full tank. Would it be forcing it up through the vent hole somehow?

 

[Wyomingcowboy]

I moved the bed back far enough to see the top of tank and see a cap that has been worn through. It is actually a hose clamped over top of a fitting. The picture on all Data calls it an "auxillary capped fitting". Could this be the source of my leak? I see nothing obvious.

 

[B.G. Smith]

Yes, that is a non pressurized (not supplied by fuel pump) fuel supply for like an auxiliery generator etc. bg

 

[Wyomingcowboy]

So if the heat of the shop forced an expansion inside the tank could it force fuel out that fitting? It was a fairly slow leak - almost like a weeping. (Maybe a few pints over 5 hours. )

 

[EDankievitch]

There are 2 hose nipples on the top of the fuel tank for use with the emmissions system on the gas version of our trucks. Dodge caps these niples off. It's common for the cap to pop off and it to leak. I used some 1/4" fuel hose and connected the t2 together and "T" them in to the tank vent with some home made plumbing fittings. Oh, the one (nipple) under the cab is in a pocket recess that will collect water and allow water to get into the tank.

 

[Wyomingcowboy]

Excellent, thanks!