Fuel Tank Vacuum

[ou sont les biscuits]

I've been having problems with a big vacuum developing in the fuel tank. To the point where getting the filler cap off has been a problem. A side effect has been that the car shunts badly below 2,000 revs, which is a pain in traffic.

The vacuum can only be caused by the charcoal canister not allowing the tank to re-pressurise after venting the contents of the canister into the plenum, or a blockage in the pipe runs between the tank, the roll over valve and the canister.

Having taken the system to bits, I found that there was a bit of the pipe that links the tank to the charcoal canister had kinked and crushed just where it exits the filler neck, and there was a bit of a restriction in the roll over valve. I've cut out the bit of collapsed hose, and by-passed the roll over valve with a piece of fuel hose.

This seems to have sorted the problem, although I haven't really done enough miles to check.

Anyway. Do I need to replace the roll over valve? Someone in the TVR fixing trade said to me that I shouldn't bother, given that if I ever activated the roll over valve, a bit of leaking petrol would be the least of my worries, but it would be good to know what others think

Fire away. No pun intended.

[FoxTVR430]

I would replace it as a matter of course.
Think of the insurance company's.
God forbid that you need them of course.
They could see this as a removed safety item and therefore not pay-out.

[Loubaruch]

When I replaced my fuel lines a few years back I remember breaking the plastic roll over valve.

From memory I replaced it with an aluminium one from Merlin Motorsports they had a good selection. A much stronger item.