Hi all, I wonder if anyone has any thoughts on how I can resolve a problem I found when I was out on elsie last weekend? I noticed, after filling up with fuel, that as I was riding around it was leaking out past the fuel cap into the 'well' around the filler neck and then running down the side of the tank. I tried refitting the cap a different way round, but to no effect. The rubber seal inside the cap is fitted with the lip facing towards the tank and I have a spare fuel cap I tried, that also leaks in the same way. Looking at the top of the tank where the cap fits, there appears to be some damage to it, which may be causing it not to seal correctly. Hopefully the pictures show this clearly. Does anyone have any ideas how I might 'bend back' the part of the neck which is damaged? or if there is any other way to stop fuel leaking past the cap and onto the tank?
That looks like there is a dip around the sealing area where the rubber sits
I'd try and build it up level with some fuel resistant epoxy
That was my thought as well, the slight stain on the paint indicates this is where the fuel appears to be leaking. I had thought to try and build it up with some epoxy, but wasn't sure if that would work.
I resorted to using my old aftermarket cheapo cap to stop the leakage
Was it Stusco who used the seal off the aftermarket cap and put it on the genuine cap?
The caps have an internal spring don't they ? Could the tension be altered to make the seal "grip" better
I'm not sure what cap it has, I'm guessing aftermarket as it's got the central key not offset, though it does have one key for all locks. I'll pop up a pic later. The spare cap has a different key, looks the same, and has the same problem. I'm not sure how to strip the internal spring from the cap to try to increase tension, though I did notice the cap can be twisted a small way, side to side, when in the 'locked' position.
Ok, in case anyone is interested, I managed to find the problem and hopefully fix my leaky fuel cap. Not sure it will help anyone else, as it appears quite a unique problem, but I was pleased with my detective work and wanted to share!
I was looking closely at the tank filler shape, where the fuel appeared to be leaking and the shape compared to the opposite side, which appeared to be sealing. At first I thought it was the 'gap' had been bent down and was leaking fuel, presumably by someone tying to lever off an old fuel cap for some reason. Then feeling under the rim and looking square on to the neck, I realised that the inner 'ring' of the filler neck had been bent upwards (again presumably to release a stuck fuel cap) and thus the rubber gasket in the fuel cap was probably not sealing on the 'outer' ring of the filler. I think this can be seen in the first picture.
So I removed the tank and carefully placing it on a blanket, on a pallet, with rubber gloves and mats taped to the top of the tank, to protect the paint in case I dropped something on it. I then used a hammer and a clutch centre rod and gently hammered the part of the inner neck that was standing proud, until it was below the lip of the 'outer' ring. I think this can be seen in picture two, I know it doesn't look like it, but the 'finger' test tells me it is no longer proud of the neck.
Putting the fuel cap back on it felt nice and tight and engaged properly with the cut outs in the filler. I left it overnight with a near full tank and the faint whiff of fuel I could smell before has now also gone. So it looks like Sherlock has done his stuff and the Smithy has finished it off. Happy days 😁