Fuel leak

[yahrt]

My car has been done for about 1 year. I have only filled the gas tank past the 1/2 point on two occassions. Last Fall I filled to about 3/4 full, parked the car in my garage. The next morning the garage reaked of gas but there was none on the floor. Went for a ride and emptied the tank below the 1/2 full level. Parked the car and did not have gas smell the next morning. Since then I have never filled up the tank >1/2, until last weeked. Filled to over 3/4, parked the car on Sunday. Didn't get back into the garage until Sat and it reaked of gas. I pushed the car out of the gargae and there was a trail of fuel on the drivers side. A full inspection showed a clean engine compartment, dry fuel lines from front to back, dry filler neck gasket, dry fuel sender/pump seating, and the air vent hose still in the normal position as installed. The only thing I could see was fuel dripping from the plastic belly pan for the fuel tank. I pushed the car forward and back a few times, and a bit more sloshed out of that plastic pan. So it seems I have a tank issue. It seems to be a slow leak because after a few more pushes forward and back, no more spilled out. And today, after a ride yesterday, the tank is <1/2 full and all appears fine. Since it only seems to be an issue when >1/2 full, i am guessing that the leak is where the two halves of the tank are joined. Probably too long of a post for a simple question, but is there anything else I should consider/has anyone had this issue. One would assume these tanks are pressure tested when manufactured, but I am thinking that the tank arrived in this condition. Thanks for any insights. TY

[Higgybulin]

Did you use the Factory Five seal that attaches to the tank and receives the filler tube? Do a search, that is probably the problem. Look for the OEM Ford part.

[yahrt]

I used the OEM part, and there was no sign that the leak was coming from that location.

[boat737]

With leaks, anything is possible, especially the frustration. The leak can be far away from where it is dripping. I would say to check the tank seam as best you can, but don't rule out all the other openings in the tank as well, even the openings on the top of the tank for the pickup, vent, and sending unit. (hopefully you have the access panels in the trunk for those.) Check all the fittings in the fuel lines, return lines (if you have those), and vent lines.

It's possible that all that is fine, and no tank problem. So make sure your filler tube (from top to bottom) is all sealed up and good, because if you are fueling, and spilling out the filler tube somewhere, the gas could be collecting in the plastic belly pan. I've never heard or seen that, but like I say, with leaks, anything is possible.

You'll find it. It's a process.

[egchewy79]

Might be the seal at the sending unit as well. If you don’t lube them up when installing they can tear.

[phileas_fogg]

As Chewy says, check the seal at the sending unit AND at the fuel pump hanger. If you put the sealant on these large O-rings as shown in the F5 video, you're almost guaranteed to get a leak. The sealant gets hard, vibration cracks the sealant, and fuel spills out the cracks.

When you reinstall the O-rings, use a bit of motor oil to let the retaining ring rotate around without messing up the O-ring.


John

[Al_C]

Might be the seal at the sending unit as well. If you don’t lube them up when installing they can tear.

I agree. If everything is good when the tank is less than 1/2 full, I'd zero in on the sending unit connections. I had the O ring on the fuel gauge sender go bad, so this is a possibility. The pump hanger connection is higher. It could be the problem, but at 3/4 full, I believe that connection is out of play.