flymo petrol L300 wont keep running?

I have 2 flymos with two stroke tecumsch engines that do this, i suspect that the light weight of flymows causes vibration to wear out parts in the carb. I had one carb with a float valve system develop a leak in the float itself. Information and parts for tecumsch carbs seem to be available online. Try a carb kit overhaul.
I have had trouble with petrol cap vents getting blocked as well, and this is the easiest cause to diagnose so investigate this first.
Another problem is the fuel taps which tend to develop leaks. Without a fuel tap the fuel cant be turned off and will tend to seep into the carb while the mower is not being used, either evaporating and leaving un-burnable oily residues or leaking out of the mower or both. If the petrol tap is working turn the petrol off and run the engine until it stops before putting it away. I don't have the taps fitted any more cos they leaked and i could not find replacements so I always drain my tank now before putting the mower away.
I have also read that this can be caused by a leak of air into the crankcase that only opens up with heat. Old cracked gaskets or shaft seals would be the culprits here.

David Bean
November 2016

Check the air hole in the petrol filler cap. Mine was blocked and would start then stall.

Eric
July 2015

I have the same problem - check the spark - my magneto is u/s.

Christopher.
June 2009

sounds like a definate carb problem. If you haven't used it in a while the oil has probably gummed up the inside of the carb. you'll need to clean it up thoroughly using some carb cleaner. If it has the small walbro type carb it could need a new pump diaphragm. a carb overhaul kit for one of these is quite cheap. just spent the day getting three of these of varying vintage going all three had gummed up carbs. hope this helps if not let me know what type of carb it is and we'll go from there.

frogman
July 2008