Fuel sending unit micro crack (temp fix)

[OldDuck]

Today, I finally won against the gas the puddle under the rear passenger seat. I just wanna share what I did as I'm sure most e31 owners will come across this issue.

So I have been battling the gas leak issue for awhile.
I replaced most of the hoses related to the fuel, rebuilt fuel pump, changed fuel sending unit gasket, installed vent valve from Nissan, and still got puddle of gas under the car.

I decided to remove the rear seat again to check the fuel sending unit, but this time with full tank of gas, and finally found the culprit! Gas was leaking through the micro crack in the plastic of the sending unit.
leak.JPG

I was about to order the new fuel sending unit from v12throttle for $900, but decided to try the cheap fix first. I remember reading about people using epoxy to fix micro crack, so I gave that a go.

The stuff I use for this is JB Weld Kwikweld 50176 + JB Weld Waterweld 8277.

This is the area that is prone to micro cracking, so if you want to try what I did, make sure to clean this area very well and lightly sand it down
micro crack area.jpg

After cleaning and sanding, I first applied two layers of JB Weld Kwikweld
kwikweld.jpg

Then I applied another layer of Waterweld on top of Kwikweld after about 8 hours, it's probably overkill, but I just want to make sure it's strong enough. lol
waterweld.jpg

After 24 hours, I put the fuel sending back in, start the car, and there's no more leak coming out of it.
I put temp fix in the title as I don't know how long this will last. I will report back if this repair failed in the future.

Total cost to repair: $15.66 + tax

[dragon850]

Good job on actually stopping the leak for a while so you can at least drive the car!
This repair will last few weeks to a month and will start leaking again.( I have seen at least 50 units in for a rebuild that have been JB welded in this fashion and started to leak again).
Better repair is the method I developed when I was specializing in rebuilding these units before offering new assemblies.
It's chemical welding but from the inside of the cap.. you would need to disassemble the pump assembly completely to do this. However even this repair only lasted a few months and I started to get warranty returns, this made me stop attempting to fix the leaking caps and only rebuild the pumps that have not developed microcracks yet.

[OldDuck]

Thanks! I'm happy to be able to drive it around again without seeing the damn fuel under the car.
I will order a new unit from you as soon as I see it leaks again.