Originally Posted by Blakeya

Almost defo the cold start valve as previously stated. The cailbration normally runs this valve for cold start when the ambient air temp is below -5DegsC (Very rare in the UK). Th starting problems seen with this valve connected & not in use is caused due to the Cold start valve going faulty & leaking fuel at all times. Disconnect it & forget it! It will be fine!!

Regards
Andy