What are the things wrong with a lawnmower that will start, but then dies?

the most common cause is dirt in the carburetor on those ,most of them don't run a filter and dirt builds up in the tank and causes the needle valve to stick on them or dirt clogs the main running jet on them,id try cleaning it out and see if that helps it,most of the time it will and also try changing the spark plug they will do that also,good luck.

Sounds like you have a dirty or clogged carburetor or carburetor jet. Did you leave it for the winter with gasoline in it? Do the various 'arms' on the carburetor (choke and throttle) move freely, or is there a lot of junk and debris on them so they stick open or closed?

Often, adjusting the carburetor jet on a small engine is enough to break off the 'gunk' - the screw to do this may be on the side, the top, or the bottom of the carburetor, depending on the model of the engine. If you can identify it, then tighten it by half a turn, loosen it again EXACTLY the same amount, and try to start the engine again. No guarantees, but that often helps.

hi curiously as in case you placed the incorrect blend of oil to petrol,i'm hoping you're using 2 stroke oil, you will desire to empty the petrol tank,flow away exact open for greater or less 2 days for any left to evaporate,Then blend in separate petrol field with petrol/oil to the education on the two stroke oil tin/bottle,if no longer there, im uncertain, yet your close by storage will know.top off the mower petrol tank to obtain new blend, do no longer fill with lot in simple terms a small quantity in case you have an identical hassle lower back, drain as previously because of the fact there would be some left in the pipe from tank to mower.yet i think of it incredibly is going to be ok first time good slicing John

the fuel pump can get clogged or have impurities on the screen which will shut it down. make sure the pump assembly and gas tank are clean from garbage. and make sure there are no fuel leaks.