kerry.king

I have a 75gal aux tank in the bed of the truck, that is plumbed into my fuel filler neck thru a pump. When the tank is full if I leave the valve open that I have in-line, it will gravity feed thru the pump and keep my tank full. It never over flowed, just once it filled up to the spot I tapped into the filler neck it balanced out and stopped. Yesterday I noticed the valve was open and a puddle of diesel on my driveway. I got under and looked, and fuel had leaked from on top of my tank. Can't see from where exactly, but I was able to get my hand up there and feel around and it felt like it came out around where the pick up tube and all go into the tank. Like a round 2 or 3 inch across fitting or something. Similar to where a fuel pump would be if it was in the tank I guess. Is this a place that our trucks have issues? Is there possibly a breather that let some out? Do I need to drop the tank and replace a gasket maybe?
Any and all advice/help is appreciated.
Thanks,
Kerry

Dieseldude4x4

Just pulled my tank to replace the fuel level gauge. There is only one penetration on a stock tank and that is the big three or four inch assembly that holds the sending unit in top of the tank. There are however, several penetrations through that piece of junk. Obviously the fuel pick up, the return to the tank from the VP-44, a roll over valve, and one line that is capped. Could be the big plastic nut is loose or some of the rubber bushings are degraded nad leaking. Or the roll over valve could be burping or the one line that is capped could be degraded and leaking. I doubt you have a hole in the tank because when I went to drill a hole in the tank to add the FASS big pick up tube, that tank is about 1/4 inch thick or more and very tough stuff. Shine a lignt in over top of the left rear wheel (s) and you may be aboe to see where the fuel is seeping out of. I used a motorcycle jack to lower my tank. Did what I had to do for the new pick up tube, and lifted it back into place with the same jack. Worked very well and no leaks.

Sleigher

I had a leak there once. All I did was tighten the big nut and it was ok.
I've dropped my tank two times to replace the sending unit.
The last time I must not have tightened it enough or the gasket slipped.
Either way has not been a problem since and that was at least five years ago.

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kerry.king

do i need to drop the tank to tighten the nut? if i drop it, should i go ahead and replace the gasket on the big nut? I have a motorcycle jack also, what i was planing on using if i need to drop the tank. how difficult is it to drop the tank?

Sleigher

When all I had to do was tighten the nut I was able to do it with the tank in place.
It is not that hard to remove the tank.
The first thing you have to do is use most of the fuel.
I may have used a floor jack but it isn't heavy when it is mostly empty.
There are just the two straps that hold it in place.
The hoses need to be disconnected and the wires to the sending unit.
Then you just loosen the straps and it lowers down.
It has been at least six years so I may be over simplifying things but you haven't much to lose by reaching up there and seeing if you can tighten the nut.
If you can't then you might as well drop the tank and get a better look at the problem.

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kerry.king

I seem to remember when I installed my fass unit that I had to use a special wrench to unhook the fuel line. Hoping I don't need one this time. Can't remember how the fass line hooked up. The wires are just on a harness right?

Sleigher

I think the fuel lines have a special fitting that you push in and pull out on the hose.
I replaced mine with hose clamps years ago.
I don't remember the wiring. None of it was terribly complicated.
You can actually drop the tank partially and then go after the connections when you can see better.
Everything but the filler hose, which has to come off first.

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kerry.king

Sweet, thanks for advice. It will be a couple weeks before I get home to work on it. I'll let you know what I find.