Fuel leak??

[Dan:)]

I've done about 20 miles and my tank was full now it has dropped below 1/3 of the fuel guage. The driving isn't careless as I've got to keep the revs under 2k as I've to bed in the headgasket replacement. I can't see any leaks anywhere so what could it be??

This is on a standard 1.3 2f Polo by the way si I should be getting better fuel economy than that surely.

[Jezza-7]

Does it smell like its burning a lot of fuel?

Best thing to do is put an old white sheet/blanket down and drive over the top, leave it running and look for any drips/leaks.

How sure are you it was full and not just a faulty gauge? Mine has read 2 gallons once and i ran out of fuel.

[Dan:)]

Nope no smell of burning fuel.
i'll try that sheet thing you mentioned.
I know its a leak as the guage reads as I fill the tank up as normal so thats what lead me to believe its  a leak

[Jezza-7]

Or another method we use a work for leak finding on the aircraft gearboxes is to put french chalk (like flour really) over the gearbox as it will show leaks. Could try that from the tank to the engine. Might get a little messy on the floor though.

[cheys03]

You can usually smell a fuel leak quite strongly. The fuel gauges are not known for accuracy. Have you definitely had a full tank and gotten to a point where you've run out of fuel or had to put in nearly a whole tank's worth after a short number of miles?

[Dan:)]

I'll try the french method with the chalk. thanks for that
I usually have to put in nearly a whole tank's worth after a short number of miles (less than 100)

[AlexG40]

Most likely cause is a crack in the filler neck, but like said above you'd be able to smell it for sure.

[ereeiz]

I've had to replace countless tanks, always a PITA. Always gone where the neck bends and mud sits on top = corrosion. Or where the tank meets the neck. I'd bet LOTS on it being that. Especially if it's happened after nothing has changed.

Also, if you've done your HG, I'd check you have the fuel pipes connected properly and they're not split, undertightened, overtightened, correct clips used, etc.

[G40supercharged]

I had a leak from the fuel filter under the back by the tank. The thin alloy body of the filter had corroded under the metal strap that holds it on. Only leaked when the engine was running and it was under pressure.

[DMWG40]

glad you found it