91 comanche gas leak

so i know subarus very well got a very low one actually. So i found this guy online that wanted to trade straight up a mountain bike (i got for free) for is 91 mj with 91k miles on it. First night i got it figured it would have problems, but i put gas in the tank and it all started running out the bottom. Dove it actually for a while, the lower the tank went down the less it leaked. I think it may be 1 of 3 problems 1, might be the tank itself rusted out 2 the filler tube might be cracked or 3 the gasket might be leaking. Thats my thoughts, now i dont know how to go about doing this or what to check/do first. Could it be something else? what should i check do or whatever plase help!!! dont know much about this from so pm me with answers or any help thanks!!!!


Ian

Things that make tanks leak:

Rusted through--replace tank.
EVAP/roll over valve grommets deteriorated--replace.
Fuel pump assembly flange gasket bad--replace.
Rotted/rusted fuel lines--replace.

so what is the best way to figure out what it may be???

Craw under it with a bright spotlight and take a look-see.

Unless you're daily driving it, I'd drop the tank and find out for sure.

WHOA! You're in Grafton and own an MJ?

I'm in Worcester and daily drive mine :cheers:

Careful pulling the j-bolts on the tank straps, yours are probably pretty corroded and you can't order the bolts anymore, so what I did is cut the straps (which you can buy online for cheap) and then wire wheel all the rust and junk off the bolts before unscrewing the nuts.

kastein said:

Unless you're daily driving it, I'd drop the tank and find out for sure.

WHOA! You're in Grafton and own an MJ?

I'm in Worcester and daily drive mine :cheers:

Careful pulling the j-bolts on the tank straps, yours are probably pretty corroded and you can't order the bolts anymore, so what I did is cut the straps (which you can buy online for cheap) and then wire wheel all the rust and junk off the bolts before unscrewing the nuts.

Click to expand...

You can get replacement J-bolts, they're just not for a Comanche specifically.
Find a local fastenal, they have concrete anchors that are the right size and shape. They held mine in OK, until I tore it off on a big rock in Moab.
When I took the tank off the bolts tore out the mounts on the frame, so the bolts are plenty strong.

Ah, good to know!

A lot of people use bent carriage bolts, but I'm kinda nervous about getting the bend and whatnot right without weakening them. I bought a bunch of extra XJ j-bolts in the hope that I could modify some of them to work nicely on the MJ, but the MJ bolts are far shorter and the threads start way closer to the head on the shank.

Hey thanks guys, hey kastein where in worcester do you live, is there anyway you could help me work on it. It is not my dd right now but i want it to be soon, i have a subaru wrx that has a bunch of work done to it, but i did most of the work in vermont. I live in a condo place in grafton so there is no where for me to work on it... what ya think???

Tank was at fault:


That's what happened with a single stomp... whacking it with my hand resulted in a 7+ inch long crack opening. Dragging it out from under the MJ caused it to start leaking badly from the bottom, as well, I guess it knocked the remaining rust loose and opened up a few more pinholes.

New tank is in and working great... needs some exhaust work and a brake line or two though.

Hey Ian, Glad to see you signed up on here. :cheers: Go Red :scottm: