Fuel Leak Help

[lesvignes]

Hi, just found petrol is leaking into the boot space of the Cerbie, wet all the carpeting, any ideas where it might be coming from. Darn't use car at all.

[Tony69]

Hello,

my guess would be that a seam on the fuel tank has a fracture and it is slowly leaking fuel.

if you remove the carpet/fabric cover above the tank that covers the control units, look to the top left and you'll locate the "roll over" valve. remove it from its bracket and disconnect the two rubber pipes.

one of these pipes is connected to the fuel tank and allows it to "breath". as the fuel is sucked out, air is allowed to be drawn in through the valve. in the case that the vehicle is overturned, the roll over valve will close and not allow fuel to escape.

anyway... one pipe will not and should not offer much resistance if you blow down it... the other pipe will be connected to the fuel tank. if you blow down or apply gentle/low air preasure with something like a modified foot pump, the preasure gauge should remain constant and no air should leak out. if there is an air leak then you have a problem.

a possible cause of stress on the fuel tank that could in time cause a fracture or leak... is the roll over value itself. the original unit is Ford and from a Senitor I think. anyway it is a rubbish part that I replaced as I kept getting high presure or a powerful vacuum in my tank because the valve was not allowing the tank to breath. I did try a new ford replacement but that was just as poor as the original part.

the constant preasure followed by vacuum followed by preasure etc... causes the tank to continually flex, needlessly stressing the seams in the tank. Replacing the old ford valve with a little aluminium Mocal part resolved the problem for good.

anyway...

1) Syphon out whatever fuel you can before going any further and store in sealable metal fuel containers
2) Test your tank with gentle/low air preasure to determine if there is a leak in the tank.

The old ford roll over valve may have been a contributing factor to causing a leak, if you have a leak at all. I don't know of any other reason why you would have a fuel leak in the boot.

anyone with any other ideas?

[Tanguero]

There are three connections to the back of the tank. The feed to the pump is at the bottom on the passenger side, the vent (via the rollover valve) is higher up on the same side and the return line from the fuel rail is at the top on the drivers side.

If it isn't leaking from one of those fittings then the other possibilities are either that the tank its self has a leak or that you over filled it and left it in a warm place causing the fuel to expand and push out of the filler or rollover valve.

[mickydoo]

I had a similar problem associated with a light whiff of fuel in the passenger cabin.

I investigated and in fact the rubber connector hose between the fuel filler cap assembly and the fuel tank feed pipe was perished and the o-ring holding the fuel cap assembly in place was getting loose. That was contributing to petrol sloshing around & leaking out of the tank in very small quantities when I went around corners with any moderate speed. It was generally worse shortly after filling up (obviously as the fuel was further up the tank).

Temporary fix was to remove and refit the o-rings much tighter and subsequently arrange for the garage to get a replacement length of suitable bore fuel hose.

[lesvignes]

Thanks for all info, just investigating as fuel has now dried up in boot and can expose the hoses etc. Any one had to buy a new tank? if so where is the best place and is it expensive and difficult to fit? Will keep you posted on progrss.