Gas Leak, Where Could It Be Coming From?

ccrider · June 26, 2008

There have been several occasions over the last year when getting out of my truck after parking it, I would smell gas.

I have a 2003 1500HD. Just the other day after getting home on the driveway from a recent fill up, I got on the ground and looked under my truck to see a wet spot on the bottom side of the gas tank.

I have since monitored it over the course of a week and it has not come back yet, obviously there is a persistent problem. Has anyone known of similar issues and what the root cause is? I don't want to take it in until I can see for myself and describe in better detail what is going on. I have not made the correlation that it only occurs after fill-up , it may occur other times as well, I just dont remember the other instances in the past year.

Any help is appreciated, I did search this for 1 hour and found one hit, yet there was no root cause entered in the thread.

BigJayDogg3 · June 26, 2008

Could it just be overflow?

ccrider · June 26, 2008

Could it just be overflow?

If you know of an 'overflow' port then this info would be would be helpful. Are you saying there is an overflow port?

I wouldn't think the mfg is going to design an overflow where gas comes out and flows around the tank to the undercarriage.

But you have over 3300 posts, so I would think you know something here, please say some more.

BigJayDogg3 · June 26, 2008

IDK either, it would just seem to me that you would have to have some kind of hole somewhere so the tank can take in air so it doesn't implode on itself, and when you are filling, it doesn't fill to the point where it is coming out of the neck. I haven't filled the tank to that point yet, so .

And as for my 3300 posts, the vast majority of them are BSing with other members (), and asking questions myself so...

98silvz71 · June 26, 2008

Did one of the filler necks come off the tank. There are 2 necks, one for the gas to get into the tank and the other for the air to leave the tank when filling. Reach up inside the bedside and feel to make sure the necks are still connected. When I dropped my tank on my 98 I was sure that I didn't get on connected back up and thats all I can think of where the gas is coming from.

ccrider · June 27, 2008

Did one of the filler necks come off the tank. There are 2 necks, one for the gas to get into the tank and the other for the air to leave the tank when filling. Reach up inside the bedside and feel to make sure the necks are still connected. When I dropped my tank on my 98 I was sure that I didn't get on connected back up and thats all I can think of where the gas is coming from.

I reach up and stuck my head up there when I got home ,. and I could actually lift the sendiing unit (?) up !! Un-believeable! A four inch wide hole in the top of my gas tank. Nothing is securring it. Feels like there is a collar that is to secure it, I was actually able to take some pictures of it ( Hope I know how to attach to this post.) There are some 'hooks' on the tank, and the collar has some slits, but I can not seem to fasten it with my hand.

- Does it take a special tool?

- What will the dealer charge to do this?

- What would a mechanic charge?

- Does it involve removing the gas tank?

ccrider · June 27, 2008

Did one of the filler necks come off the tank. There are 2 necks, one for the gas to get into the tank and the other for the air to leave the tank when filling. Reach up inside the bedside and feel to make sure the necks are still connected. When I dropped my tank on my 98 I was sure that I didn't get on connected back up and thats all I can think of where the gas is coming from.

I reach up and stuck my head up there when I got home ,. and I could actually lift the sendiing unit (?) up !! Un-believeable! A four inch wide hole in the top of my gas tank. Nothing is securring it. Feels like there is a collar that is to secure it, I was actually able to take some pictures of it ( Hope I know how to attach to this post.) There are some 'hooks' on the tank, and the collar has some slits, but I can not seem to fasten it with my hand.

- Does it take a special tool?

- What will the dealer charge to do this?

- What would a mechanic charge?

- Does it involve removing the gas tank?

What is this piece? the sending unit? the level gauge? the fuel pump? or what?

I want to take it in first thing in the morning as I need to get this fixed. I plan on towing a trailer and taking the family camping after July 4, starting on the Sun July 6. This really scares me now, I know I've been driving it like this for a year or so, but now that I know I dont' even want to drive it to work tomorrow.

tobias · June 27, 2008

I believe it is all of those things wrapped up in one.

alaska511 · June 27, 2008

You can drop the tank after unplugging the harness. There will still be a ground wire attached that you must remove before the tank will come out from under the truck. Squeeze the 2 tabs on each fuel line to disengage them from the bayonette fitings on the tank

I would replace the entire sending unit, you will get a new seal ring with it. The unit locks in place on those tangs you see on the tank.

2005LT · June 27, 2008

Just looking at the connection, those tabs along the outer ring of the sending unit with the slits in them look like they catch on something if you push down on the whole unit and turn it to lock it in place. Have you tried that yet? Even if it catches temporarily, it may get you around until you get a replacement (if you wish)? Just an idea.

98silvz71 · June 27, 2008

Drop the tank-

Unbolt one the strap holding the tank, let it rest on that crossmember, unplug the pump and unscrew the ground wire, lower the tank (at level height the fuel lines will let the tank touch the ground), and take off the fuel lines.

Then you can take out the sending unit, put a new gasket on it (make sure to put Vaseline on the gasket or you will never get the sending unit to slide down), spin the collar of the sending unit to lock it down, and tada you are finished. For added security you could put a bolt, zip strip, etc on the collar to secure it to the tank.

ccrider · June 27, 2008

At the dealer early this morning, got a pictorial view of the assembly, then decided to bite the bullet and drive in the service center. Discussing with an actually pleasant rep about the issue, I had full pictures for him to look at. The obvious question is has anyone touched it. I was asking if it could be covered under warranty as I could not see how it would ever come undone on its own. Well, he looked up the history on his computer and turns out I had it in there 1 year ago for 'cold start, hard starting in the mornings' type symptom, and they at that time had replaced the fuel pump sending unit. He quickly said immediately after looking at his CRT that 'it is covered under warranty" , how nice of him. Anyway, I was actually relieved that I wasn't looking at a $600+ bill .

I could have been toast, quite literally anytime between their last service and today.

ROOT CAUSE: dealer did not secure the fuel pump at an earlier service 1 year prior to today.