Topic: Leaking fuel sending unit

[Building 3]

I have had a very good summer driving my 1966 convertible. I have used up many gallons of gasoline but never filled the gas tank to the absolute full level. I few days ago I decided to fill the tank right to the top for several reasons. First to get a really good reading of the fuel economy and second because it may be the last fill before the snow arrives. I filled the tank. Drove it home and parked it in the garage. The next day I found the fuel sending unit leaking at the front of the gas tank.  One drop every nine seconds. I was stunned because the car has been so reliable over the last five years.  Nothing like this has happened. I told a friend about it and he said that it could be a pressure build up in the tank. If the tank was full to the top, since there's no vent it could have blown out the seal in the tank. Any opinions? Thanks.

[J_Speegle]

If it has an original gas cap its vented so (if in good order) there shouldn't be a build up of pressure.

Might be a gasket that just failed or the sealant/weld around the wire junction or fuel pick up.

Tissue paper test should help you focus on where its most likely coming from

[Building 3]

Yes it is the original gas cap. Good to know that it is vented. The whole sending unit around the circumference leaked, so I assume it is the O-ring that failed. I am only using ethanol free gasoline so I am surprised about the failure. I new O-ring should fix it and I will monitor it. thanks.

[NEFaurora]

Time for a Sending Unit O-ring replacement obviously!