tommyeflight89

iTrader: (4)

Hi guys,

Bit of a rookie mistake with my 82 FB today... I overfilled the tank. I could hear it filling to the top and then the gas pump cut out.

Shortly afterwards, gas started to leak from somewhere near the filler neck and tank junction area. Slow to moderate dripping.. it eventually stopped.

Got the car home, took the plastic shield off (inner fender thing) and could see wetness from fuel around the sender unit area.

Now, I closely inspected the rest of the tank, used a mirror and checked the perimeter... no other evidence of fuel. Seems to be isolated exactly to the sender unit. So that made me feel good.


The tank was recently removed, cleaned, and recoated by a reputable shop. The sender unit was replaced with a new gasket also. I have the paperwork. The condition of the tank etc is mint.

Any advice here?

What I think happened is when I overfilled it, there was a bit of pressure that started the leak. What I am hoping is as long as I don't overfill it, I should be fine.

I may try tightening the sender unit screws a bit, maybe the gasket is a but crushed and needs to be tightened down.

Is it possible that the fuel could come from the junction of the sender unit plate and connector body??

I wanna try and get some of the gas out of the tank.

Also, I will post more on the car later, got it Friday from a Local member. Loving it so far!

RotaryEvolution

iTrader: (30)

recheck the screws to the sending unit, some shops are paranoid about snapping the screws so they might be just cinched down but not tight. they have to be rather tight on the FB since the sender sits below the fuel level, and hopefully the new unit didn't come with a cheap cork gasket(if so it should be completely dressed with fuel compatible gasket dressing).

tommyeflight89

iTrader: (4)

Good advice!

I actually just finished rechecking the screws, they were not completely snug, I tightened all of them maybe another half a turn or so.

I will re-level the car and see what happens, perhaps it will be ok now.

-Tommy

Edit- Well its for sure leaking from the sender-tank joint. When I leveled the car a very small wetness started. Looks like it only leaks when the fuel has enough head developed above the sender unit level.

Removing it and using Permatex Sealant will be my long term fix. it will be tricky not stripping the phillips head screws. For now, I will get some of the extra gas out of it!

tommyeflight89

iTrader: (4)

At this point, the leak is very small. I tightened up the screws as best I could without strippng them completely.

My permanent fix will be to seal as you have suggested.

However, I am hesitant to remove the screws as they are close to being stripped.

I have searched, but have had no luck in finding the thread type on the screws. I assume it is some type of metric thread, but want replacement screws before I start the job. Anybody know?

-Thanks

JSmall

Good to see you've found the leak nice and quick!

Im wondering this also as I may need to take mine off. Will replace the screws with allen screws after. Does anyone know at all?

NCross

iTrader: (18)

To remove fuel just disconnect the fuel line on the carb and drain it into a gas can. Turn the key to ON and let the pump run. You should only need to drain 2 gallons or so. After the level is below the sender plate remove it and inspect the plate and gasket for imperfections. Clean the surfaces thoroughly with brake parts cleaner and apply a gasoline resistant sealant to the gasket and torque it back down. Dont tighten it to much past hand tight, they will strip or shear.

To be on the safe side, you can apply a bead of the sealant around the torqued down plate for extra sealing. Let it cure over night before testing for leaks or refilling the gasoline.

tommyeflight89

iTrader: (4)

Thanks for all the advice so far!!

So I found new screws, they are an M4 thread. The exact size I got was M4x8mm, they are an exact replacement.

Now, I removed the sender unit and inspected the gasket. I did not realize it has a kind of double sealing flange, where part of it seals into the recessed face. To me, the gasket is too thick, when you tighten the screws down it doesn't seat properly. That inner lip is far too thick.

As you can see, the gasket is a bit chewed up. It looks to be identical to the pictures I have found online, so it appears to be the correct part.







I cleaned up the mating face and reinstalled without sealant.. I was hesitant to use sealant because I did not know exactly what would work. It still leaks a small amount when the car corners and gas sloshed etc. Not happy.

What sealant should I use? I bought Permatex No.1 Form a Gasket that is apparently fuel resistant. It is a hardening sealant.

I am hesitant to try sealant because if it doesn't fix the leak, I just have a big mess. Maybe if I buy Permatex No.1 Form a Gasket (non hardening) at least I can clean it off if it doesn't seal.

Thanks again, very helpful forum. Can't wait till I can contribute!

Edit- My worst fear is if I keep messing with this, I will strip out a screw hole.