leaking gas from top of tank (1 Viewer)

[97ToyotaFZJ80]

I just found and fixed my leaking gas tank, and installed the GM charcoal vent canister.
The gas tank leak was exactly the same location as others show in their photos. Small crack, maybe 1/4” or 5/16”, and it was tight, hard to find. The metal in the area around the crack was slightly distorted. I don’t see the crack increasing in size as long as the charcoal canister does it’s job and keeps the tank from pressure cycling. The tank pressure cycling between pressurized and depressurized causes fatigue failure at the crack initiation site. That’s why the crack is in the same spot on everybody’s tank; the area that gets the most movement from pressure cycling, and a geometry prone to cracking (stamped rib in the tank top). Think of it the same way a piece of metal breaks when you bend it back and forth many times.
It was super simple to partially lower the almost empty (on reserve) tank on a jack, and access the top of the tank from the front. Make sure you disconnect alll hoses, electrical connectors and fill nozzle hose and vent hose. You will need to lower the tank maybe 8” to get enough room to work in there. My truck is lifted 2-1/2” so I was able to sit at an inverted position and get my shoulders and head, and 1 arm up in there to clean the paint off by hand with coarse sandpaper. Or, you can use a grinder and blow-up
I cleaned all the paint off the tank 1-1/2” around the crack I used JB Tank Weld, which is a 2-part putty, I made a putty patch that was 1-1/4” in diameter, and 1/8” thick. I tapered the margins to the tank, and painted any remaining bare metal.
I know there are those out there who likely believe this repair epoxy repair to be sub-standard, but after I looked at the situation, I believe the structural integrity on the tank will remain, post collision, at least up to the point where the original (new) tank would have. It’s a tiny crack and in an area not prone to ripping or failing catastrophically.
Address your leaking tank - I’m glad I did.

Thanks for posting this! I'm about to give this a go. When you say disconnect all electrical connectors are you talking about the ones on top of the tank through the access hole under the second row seats?

 

[inkpot]

Thanks for posting this! I'm about to give this a go. When you say disconnect all electrical connectors are you talking about the ones on top of the tank through the access hole under the second row seats?

We just drain the tank at the plug on the bottom, then we completely remove it from rig. MIG, TIG, braze,epoxy. All work pretty good. Epoxy has the most fails, but they are few and far between.

 

[Handy Al]

Thanks for posting this! I'm about to give this a go. When you say disconnect all electrical connectors are you talking about the ones on top of the tank through the access hole under the second row seats?

Yes, I disconnected all of the tank’s top side pipe and electrical connections that are accessible from the access panel under the passengers seats area. As well, I disconnect the large gas fill hose and vent that come into the rear of the tank.This is because you must partially lower the tank from the front edge to get enough room to work between the top of tank and the bottom of the floor pan.
Be sure to use a high-quality penetrating oil like Kroil on the cinch bolts that retain the straps, for several hours / days so you don’t break the straps.

Check-in: It been several months, two off road trips, and 5k miles and no leaks. Also, the initiating root cause, tank pressurization / depressurization has been eliminated with the GM charcoal canister- no more whooshing sound when I remove the gas cap to fill up !