Stiga Multiclip 50 plus lawnmower starts fine from cold and runs fine for 5-10 minutes. Then it gradually starts to extinguish. The mower has new oil, gasoline, new spark plug etc. What could be the problem ? Dirt / grass particles in fuel tank or oil chamber ?

Kenneth, June 2008

Thanks for the answer as it was correct : Problem solved! The Stiga imported said that some of the 2007/2008 models have too tight/narrow airholes gastank caps. If you loosen the cap a bit and it runs properly (doesn't stop when warm), then this is the problem. Make a little bigger air holes to the cap to fix it perminantly. This all because the vacuum in the fuel tank caused by fuel comsumption, will need to be filled by air - otherwise the fuel inlet stops working.

Kenneth, July 2008

concise!diagnosis at distance dificult.suspecting negative pressure build up in tank /flexi lines.fuel filler cap breather hole/ or engine to carb flange gasket failure.does not sound like heat related open circuit failure unless fitted with point/condensor ignition then possible condensor heat failure(rare)does sound like exess air /insuficiant fuel.try discarding filler cap first.

caine, June 2008

This is the improved question : (with more details) Stiga Multiclip 50 plus starts fine from cold and runs fine for 5-10 minutes. Then it gradually starts to extinguish. After a five minute break it starts again and does the same thing. The mower has a CHOKE gear, which helps for a few seconds when the engine is almost stalled, but even when pulling CHOKE on it stalls - there's no way to keep the mower running. The engine coughs, but in a 'nice way', it doesn't sound as it is suffocating. When the engine has warmed up, I think for some reason the engine doesn't get enough petrol. I just wonder why the CHOKE gear doesn't keep it running. The engine extinguishes from running fine to dead in a linear fashion. The engine is new, has new oil, has gasoline. There should be no missuse/accidents happened to the mower. Maybe there are dust/grass particles in fuel tank or oil chamber ? I've previously had (on a another mower) tree leaves in fuel tank and then the engine sounded like a sine-wave (motor went up'n'down in power), and this mower sounds different - it runs smootly until it starts to fade. How about possible carburetor problems ?

Kenneth, June 2008