I have established that fuel is being starved to the cylinder but there is a decent spark at the plug. If I pour a small quantity of fuel in the plug hole it starts for a few seconds. The neoprene seal at the fuel cap has started to break up and fuel spurt through the small hole in the cap, does the seal at the cap have any affect on the pressure in the fuel tank which enables the fuel to be sucked up to the engine ?

Chris Stockley, July 2010

Thanks for your help. However to elaborate further, I took the filter off the fuel pipe to see if it made any difference just for testing purposes but it didn't. Anyway I subsequently thought that if the fuel bubble was able to pump fuel up to overflow it must be ok. Also took carb apart and separated all sections but nothing obvious. Gaskets all seemed ok so reassembled and still no joy; a bit of a puzzler.

Chris Stockley, July 2010

No is the simple answer, this is just a breather to stop a vacume building up in the tank, it is nmore likley a blocked fuel filter in the tank, or a cracked broken fuel hose, failing that it is a blockage in the carb

Husqvarna man, July 2010