MTS Fuel Tank Issues

I recently installed an MTS under seat tank. The sender and gauge I installed work great... perfectly accurate. But with a full tank, after driving around a little, fuel seeps out from the sender gasket. And if that's not bad enough, the venting cap that is made specifically for this tank leaks too! After filling up this afternoon, I took a right turn, looked out over the side of the Jeep and gas was dripping out of the filler tube and onto the back tire. This is my second tankful. At first was using my old cap, which leaked, so I ordered the new cap from MTS and was really looking forward to having the filler tube leak fixed. This is frustrating...

IS anyone else using the MTS gas cap? Does yours leak? Can anyone recommend a good gas resistant sealant for the sender gasket?

How's this stuff?

Thanks...

 

My tank leaks from the filler cap as well. It's a new plastic tank, and I tried both the old factory gas cap and a new one to no avail. I've debated finding some thicker cork and cutting a new gasket for the filler cap.

 

I'd be calling MTS
others have used their tank and cap with NO leak
and I'd say no sealant should be needed on the sender gasket

 

I called MTS and was told that they have never had a gas cap leak ever before I find that kind of hard to believe, given that they must've sold thousands of tanks over the years. They asked me to take photos of the filler neck and email them in, which I did 2 days ago. No response yet. I can't wait for the MTS cavalry, so I started screwing around with it. There was absolutely NO way the cap I got (and it's the only one they seel) was going to seal my tank. I'm not sure what the gasket is made of, but it seems fairly hard, like it wouldn't compress much. I wound up going to a good hardware store here and getting some Buna-N gasket material. I used it on top of the MTS gasket to provide more thickness. Also, the end of the filler neck wasn't flat across its diameter (if that makes sense) so I took some files and filed away at it until it was flat. I took it around the block and it still leaked a little during right hand turns. So I put a thin film of the Permatex gasket sealer on the end of the filler neck to plug any leftover file marks and put the cap back on. Drove it around the block and no leaks. Went and filled it up this morning and it's not leaking even during hard right turns. Yes, it's probably a half-assed fix, but it works. I also fixed the seepage at the sending unit with a little of the sealant under the outer half of the gasket (that stuff is great!). That flange seemed to have gotten a bit warped as well during the blow-mold process or however they make those tanks.

UCDaniel, if you want some of this Buna-N I can mail you a piece. I had to buy a 1 foot length off a 3 foot wide roll. It's 1/8" thick. PM me if you want some, I have plenty. Don't use cork...it wont hold up.

 

"I called MTS and was told that they have never had a gas cap leak ever before..."

Usually people who say that also happen to stock an upgrade kit to fix the problem.

 

Yeah. They must be so busy working on that upgrade kit that they never had time to call me back. Anyway, I was wondering how these vented gas caps work and found this on the web, though mine is a little different than these--I can hear a ball rattling around when I shake mine.
http://www.cj3a.info/tech/gascap.html

 

Look at this picture from that page ...



and you can see the streamlines where leaking gasoline has marked the paint below the filler neck. My impression was that this is the standard condition for these tanks. I know that, when I put a tank under the seat in my '73 long ago, I tried a few different approaches to make it leak and stink less, and was not wholly successful. I tried putting a nipple into the filler neck and tying that into the existing vapor recovery, and using a cap I sealed up, but there was still a little leakage around the cap gasket. Seems like these caps can hold back slosh and splash, and some vapor pressure, but they won't ever seal against liquid fuel pooling up against the inside of the cap - the unavoidable sidehill condition.

 

You're right and I can accept a little occasional leakage (still talkin about the Jeep here...I'm old but not that old), but the condition I was dealing with was ridiculous. Fuel was pretty much streaming out the side just from turning right. I've been reaching down and feeling the filler neck with dread after hard right turns and I did get just a drop or two, but only once so far.