Leaking fuel cap

[Ranga]

I've noticed lately that the panel under the fuel filler cap attracts a lot more dirt than the other side. I believe it's leaking diesel from the filler cap. Has anyone had this problem, and/or know if I simply need to replace the big rubber washer in the cap?

[land864]

Yep

Had the same thing.

Are you sure it's still there

I had to do some minor adjust to cam lock fittings on cap

Bought a gasket in Melb.

Could you use an old inner tube and cut one out?

[Ranga]

Yep

Had the same thing.

Are you sure it's still there

I had to do some minor adjust to cam lock fittings on cap

Bought a gasket in Melb.

Could you use an old inner tube and cut one out?

I have some insertion rubber to make a new gasket. I think the cap is locking ok.

[Davido3957]

I have just had a leak from my fuel filler cap - searched a few message boards last night and found a story about the boost diaphragm (on the fuel injection pump) - I have a 1987 2.5td (the old leaky cav19j) anyway I was actually expecting to find a whole load of tips about the fuel cap and how to un block the pressure vacuum release valve - instead I was reading that there was a common fault which required a rubber diaphragm changing in the FIP, this was fiddley but took about an hour tonight - thats right within 24hrs of reading a post I was able to order the part (fremantle fuel injection $64) and fit it - and guess what - it only worked a treat. Last night I could remove the fuel cap and hear a loud hiss as the pressure was being released - put it back on and drive five minutes only for the same amount of pressure to be produced, and I dont mean a little bit this is some major pressure build up guys and no wonder the diesel was leaking out- I thought it was heat and expansion - turns out it was the pipe from the turbo which is connected to the FIP - the reason for the connnection is that when the turbo is on boost the pressure from this pipe actuates a part of the pump to get extra fuel in - only problem is that there is a rubber diaphragm and when it fails the air goes down the spill return pipe and tries to blow up the fuel tank - hence the over pressure - here is a link to the pictures which explain how to change one - it was actually quite easy and she started first time. Even the guy I picked the part up from today had not heard of this happening - but I promise you I have just carried out the exact process below and it has worked - and as soon as I got the old rubber out it was split exactly as shown in the pictures - I just had to tell someone.
Replacing 2.5TD boost Diaphram - LR4x4 - The Land Rover Forum