You can buy genuine diaphragm repair kits 43028-1015, currently £10.24. This is the part that often splits and lets petrol into the carbs and floods the engine which then hydro locks and basically destroys the engine
![Embarrassed :-[](http://zggtr.org/Smileys/default/embarrassed.gif)
When you rebuild the fuel tap, use the genuine kit as above, and also replace the spring 92081-1171 £1.75. Some people then suggest stretching the spring a little, to increase the pressure on the diaphragm. The original spring rusts and collapses. another cause of fuel leak.
I think that some people don't replace the spring, which then gives the impression that the diaphragm is still leaking, making them replace the whole tap.
I also flatted off the aluminium parts of the tap, using 1000 wet n dry paper on a sheet of glass, with water, to ensure a perfectly flat face on each piece. I covered the faces with a black ink pen/sharpy. and then rubbed them down lightly until all the black ink was removed.
The tap now works perfectly, but I still check for leaking fuel before starting up he motor!