Fuel tank leak... but where from?

[Erin]

If it's not one thing it's another. First my engine was playing up, and just wouldn't idle properly when cold, then yesterday I find fuel in the bilge.

The bilges were lovely and dry until I refuelled last weekend and brimmed the tank, and all seemed to be well on my first 10 mile trip. But yesterday I went down and found fuel in the bilge sump. Now there's a couple of possible causes, but I'd like some advice as to how to proceed.

I've had a good look around the stainless plate on the top of the fibreglass tank where the filler pipe, gauge sender and fuel feed are all terminated, but I can't see any real signs of fuel other than a thin film. What I can't tell is if it is sloshing around when I'm underway and peeing out the top. Having said that, I'd have thought it was quite a big leak given the amount I found in the bilge. If there's a crack in the tank, how the hell am I going to find it and for that matter repair it seeing as the only visible bit of the tank is the cut out in the floor of the console where the pipes connect?

Any thoughts?

Piccy below of bilge before leak. Float switch has now jammed due to petrol affecting the plastic.

[antiqueboy]

thanks for advice for my fuel query, fuel tanks by there nature are pretty bullet proof so i would hope the problem was else where, if you found that it was then i would bite the bullet and replace it rather than fix it
regards
nick

[codprawn]

Maybe a breather pipe is loose? Not at the tank but where the breather exits.

[fast fred]

"fuel tanks by there nature are pretty bullet proof" you would think that, and for the most part thay are, thare are Losers who put in the saddest tanks,
and close the deak so you can't see how sad it is, seen that kind of crapmanship. hopefully it's just a rubed line.
best way to check the tank is to plug the feed, vent, and put air pressure in through the filler, plug it as close to the tank as you can so to eliminate the lines from the test,
3psi is the norm over hear,should hold 4psi, custom to put a psi gauge on the vent.
FF

[Erin]

Originally Posted by fast fred

thare are Losers who put in the saddest tanks,
and close the deak so you can't see how sad it is, seen that kind of crapmanship. FF

Hmmmm, I begin to wonder after the problems I had with the hull!

[fast fred]

well I have no idea what rib your running, so it may not be the case,
another thing is some put the fill and the vent on the side of the tank, so thay can bring the top of the tank to the under side of the deak, it don't work, the fundamentals of a gas tank are simple, vent and fill are on TOP,
to the front of the tank, pickup goes on the bottom rear. as simple as that is
it not funny how many put them on the side, burpin gas out the vent, burpin out the fill, banging sounds when you fill cuzz the air is traped an can't vent.
hopein it's just a hose for ya

I've removed tanks that should have never even been filled with water, and should have never been called a gas tank.
FF

[Erin]

Thanks Fred, but all my connections are on the top as per the photo below. I've used a mirror to look at the gap between top of tank and the underside of the deck, and there's signs of fuel there, but no actual 'puddles' unless it has all now evaporated. I think I'll just have to wait until I top it up again and then look down the gap to see if there's any fresh petrol lake on top!

[fast fred]

i'd reseal them two gaskets, the send and the big plate, if you got gas leakin in the bilge with all the lines and hard ware on top, unless it's them gaskets,
it's a good posability you have blown out an upper seam on the tank, seen this before, only seen when the tank is or all most full. thats an easy one to test.

[Jono]

There have certainly been issues with "glass" tanks not laminated up with the correct resin.... after time they become porous and eventually fail. Drain and purge your tank then lift the inspection plate and check the state of the laminate.

[codprawn]

Originally Posted by Jono

There have certainly been issues with "glass" tanks not laminated up with the correct resin.... after time they become porous and eventually fail. Drain and purge your tank then lift the inspection plate and check the state of the laminate.

A worry of mine as well - but surely it would take a bit longer than this to develop?

IF the correct resin is used then they should last for ever - petrol stations tanks are often fibreglass these days.