Installed YJ poly gas tank

I just finished installing a 94' YJ poly gas tank into my 88' XJ. This is my 4th tank gas so I decided to go poly. My previous tanks were rusting inside the skidplate.

The donor vehicle was a 94' YJ 4 banger. The fuel pumps ended up being the same.

The YJ tank is like 1" deeper, and 3-4" wider.
Here are some side by side pictures:





The XJ has a tank saddle built into the unibody underneath the rear deck. I cut slots into it, and hammered it flat to get the tank to fit. The following is picture of the flatten saddle.



The wide YJ tank just barely squeezed between the frame rails of the XJ. This was so close that the filler neck and vent neck are protruding through the frame rail to get it in. This is what prevented me from moving the tank backwards to get more rear axle room.

The hole in the unibody frame rail could be enlarged and strengthened to move the tank back farther, because there is about 4 1/2" more space behind the tank.



Even with the wider tank the YJ tank is notched for the exhaust and the clearance looks good.



The sizes of the filler neck and vent tube were different sizes, so I had to adapt generic hoses to get them to fit. I also had to splice my harness on, because the connectors were different.

The YJ tank I used had a return fuel line, and the same gas vapor lines. I didn't do a late model XJ poly tank because I was told there was no return fuel line.

After I got it installed, I added two gallons of gas and it started right up. Gas gauge works, and it seems to be about 16-17 gallon tank.

Good job on the innovation, but what was the end goal? To not have a rusted out tank?

Did you ever paint the old ones? Usually water sits inbetween the skid plate and the tank, so I coated both with POR-15 on mine when I had to swap my tank out.

I rusted out one, and others get dented right through the skid plate, and it usally results leaking from a pin-hole or a seam. I figured I would try a poly tank and maybe get some more clearance to move the axle back for a set of 38"s.

hey globetrotter, you play much basketball?


looks like a good swap, how does the skid fit on it now?

The XJ tank is a little more tapered in the back, so my old heavy Tomken bathtub skidplate didn't fit. I may try a junkyard YJ skidplate.

in your use of "generic hoses" for the filler neck, make sure you didn't use radiator hose for the splice. The gas vapor will break down the rubber in VERY short order and begin plugging up the works with black goop. I used non-fuel hose in a couple trail type repairs and could see the residue within a week or two.

do yourself a favor and hit the local NAPA for designated fuel filler hose soon if it's even a question-- that goop sux and I'd hate to see you stop up your in tank filter and burn up a pump.

Hey, was out on trail with the YJ tank, and I'm getting lots of pressure at the fuel cap? Is the cap suppose release pressure? I thought those small lines to the front were suppose to burn off excess pressure in the tank?