2nd Gen Non-Engine/Transmission Major Fuel Tank/ Vent Leak.... HELP!

[GBrock]

While driving home noticed a leak. I had just filled up so I thought perhaps it was some sort of overflow vent (I don't know much about the fuel tank system). I assumed the leak would subside.



Upon reaching home, I noticed fuel pouring out of the top of the fuel tank. Crawled under truck to investigate (burned arm on exhaust pipe... !). I noticed the fuel tank cover/ sending unit nut was completely off and just dangling over the opening it is suppose to cover. I reached up to check the condition of the nut and to see if I could resecure it but there was too much muck (diesel encased dirt). I became concerned if the debris got into the fuel tank it might tax my fuel filters and ruin the injectors.



I was in a rush to pick up my luggage for a trip to the airport so I just left the truck in the driveway and had my wife take me. This was 3 days ago. I will be home tomorrow and was hopin to get to wirk on this problem when I return.



Any ideas? Do I need to drop the fuel tank or can I just clean the debris off an reseal (assuming the nut is not damaged)? Any suggestions on how I can pump out the 34 gallons of diesel out if I do need to drop the tank?



I have searched the forums for advice but nobody seems to have experienced this exact problem.



Thanks for the help.

 

[JNailor]

I just had my tank out last weekend to replace the brakeline. While it was out I checked the tank module attachment as there was some seepage. The nut was loose by about half a turn.



I think you can just put it back on as long as the nut isn't broken. I don't think much dirt can get in because the module covers the sealing ring and the fuel probably washed it off anyway.



Dana

 

[GBrock]

Thanks Dana,



I really wish more members had replied with advice as this repair was a *****.



Perhaps this info is already on the forums but I couldn't find it on any of the searches I did.



Here's the some advice I have if anyone has this problem:



1) First, as a preventitive maintainence procedure, always check the the nut that holds the sending unit in to the tank. This nut slowly loosened over time. Had I known about it, a simple tighten would have saved me a lot of time and mess.



2) In my case the nut completely loosened while the fuel was full. I probably should've just siphoned the diesel fuel out but my 5 gal gas cans were at the shop or in storage.



3) After trying to refasten the nut with the tank in place, it became obvious that I had to drop the tank in order to reseal the sending unit.



4) To do this with a full tank, I used a floor jack and a piece of 2x10 wood mated up against the bottom of the tank. As a safety precaution, I laced rope at three points along the tank and positioned them to the approximate height I was hoping to lower the tank to. I did this in case the tank shifted off the jack.



5) Using the 2x10 to spread the weight of the jack point, I jacked up the tank in order to loosen the tank strap nuts.



6) Once the nuts were loose, I lowered the tank approximately 12 inches. This gave me enough room to get access to the top of the tank and properly seat the sending unit seal.



7) This next step proved to be the most frustrating. I kept trying to wedge the seal and sending unit into the tank hole but it would keep pinching or flipping the seal in the inverse direction. This prevente me from getting the nut to the threads.



8) After struggling with it for a while I had an ephiphony and realized the seal should be removed from the sending unit and place into the hole. I then dropped the sending unit into the seal and the nut followed on to the threads easily after that.



9) I gave the nut a couple of taps with the hammer being careful not to tighten too much so as to not break the nut.



10) While the tank was down I tightened all the ropes just in case the tank shifted. It did indeed shift wen one of the jacks wheels turned and started rolling... the ropes prevented it from slipping off the jack and gave me time to reposition the jack and prevent the wheels from rolling. 34 gallons of diesel would've spilled all over the place. I reversed the process of lowering to get the tank back into position and refastened the tank strap nuts. Problem solved.





Gents, as I said, it's probably a really good idea to check that nut from time to time. I have read on here of members finding it loose. Once it's on the threads and seated, it's very easy to tighten. If it comes off and you're full of fuel. Prepare to get dirty, bang your head on the undercarriage, and maybe even burn your arm on the exhaust during the repair.

 

[Thomas]

Was raising the bed vs. dropping the full tank an option for you?

 

[Kalaehina]

Or if you're one of the lucky ones who's had to change the sending unit out 4 times, reconnect wires that disconnected because the whole module fell out of it's slots twice, then you are constantly monitoring the tightness of the nut. I tried the bed lift method once, but personally I prefer dropping the tank, just easier for me.

 

[GBrock]

I was told it would take 6 guys to help lift the bed. I didn't have a hoist nor the manpower to raise the bed.



Actually, considering all the reconnection work associated with raising the bed, I would choose dropping the tank every time. Dropping the tank wasn't difficult... . dropping with 34 gallons of diesel in is what made it tricky.

 

[Joe G.]

If you don't have any wiring mods or a 5th wheel hitch or tool box, lifing the bed is really easy. You don't have to disconnect any wireing except a ground near the front just to lift the front of it high enough to work on the fuel tank module. Remove six of the eight bolts holding it down. Loosed the two at the rear. Get a piece of cardboard or carpet to protect the paint in the rear corners from the bumper. Jack up the front of the bed with a floor jack and a 2X4. Block it up so it won't get you like a big rat trap while you are working. You don't need six guys to do that. Lots easier to get at the fuel tank module.

 

[Kalaehina]

I did mine like that the one time, looked like Rob Thomas' truck.

 

[PRout]

I know your glad that job's over with. . Ive had mine out twice now and its kind of a pia. One peice of advice for anyone working on their fuel tank module. . Always use a new seal when you put it back together. . If the old one leaks, you'll be pulling the whole thing out again. Also, if you have a full tank, it probably would be easier to lift the bed. I have 5th wheel wiring and an in-bed tank, so lifting the bed is a bigger task. The upside is, having the oem lift pump set up so I can transfer fuel either way (from the aux tank to the main, or vice-versa) Easy to empty the tank that way for maintenance, or running it through a frantz filter to make sure its clean.

 

[damar]

Easy to raise bed. Take out all bolts except the back two, loosen them as much as possible but threads still hollding. Take off grounding strap. Place a board across the bottom front of bed, then jack up bed with a jack. I've done it twice in my driveway before getting the revised fuel module, and I was 72 years old when I did it. Piece of cake if you take it easy and think out what it takes to jack it up. A bottle jack and a bunch of wooden blocks. You don't have to raise it too much to be able to remove the whole module.