lawnmower (petrol) engine – fix it or buy new?

well the ‘unkillable zombie mower’ lives on, quite by accident for now really.

i was reading through the thread again and noticed….

Not sure if lawnmower’s are ripcord/ pullstart (I’m guessing they are) but don’t just go flalling away on the cord – SLOWLY pull and turn the engine over till at TDC (maximum resistance on the cord), let the cord go back in, slowly take the slack out then give it a good pull. Repeat until started.
Pull cords will thank you.

thought nothing ventured and all that so tried it.  still nothing.  just sat staring at it and with my super-scientific boffin head on i thought ‘well if that squidgy prime button leaks its maybe not even priming it but just drawing air in’.  we’d discounted filling it as it already has petrol in it, but i thought i’d at least try filling it up, so that even if it leaks a little, at least therell be fuel behind the button for priming.

so….. filled it to the brim and it struck up!!  no idea how scientifically correct that theory was but its worked.

not resting on my laurels tho, it does need a service, so ill order a new kit including ‘squidgy prime button’ when i know which is the right kit to buy.

thanks for your help chaps, it lives on!

In my experience lawn mower mechanics are very helpful and like to share their knowledge, parts purchased from them whilst more expensive are usually the correct ones!

Carb kit or new carb both cheap and easy to change. Put in an inline fuel filter.

still it lives!

after getting it started for the last cut by just topping it up, this now didnt work a couple of days ago, so i waited patiently for my ebay service kit to come, wife chuntering away in the background about it being the final straw, its definitely had it now, links to shiny new B&Q mowers being constantly sent by messenger 😀

kit came yesterday, followed the youtube video to the letter (thanks for the link @mugboo) and put it all together again.  only thing i couldnt do was take the ripcord top off as one of the bolts was rounded off but…… lets give it a try.

also changed the air filter (didnt fit quite as well as the old one but the old one was really manky) and the spark plug (no feelers so couldnt check gap) and the priming button.

smug look towards my onlooking wife as i pulled the cord and….. nothing.  b*st*rd! 🤬

started thinking about what the problem could possibly be and checked the fuel again.  half full.  nothing to lose by filling it, tried again and bingo, it worked!!

well…… i dont like to think that this is beyond me so i looked more closely at the priming button.  i think that its all ok but thought id run a couple of things by you experts 😉

firstly, i wasnt sure that the locating clips on the new button definitely pinged into place, altho they were definitely down as far as they could go. i even pushed a socket over the ring and pushed it as far as it would go, just not sure that the aftermarket locating ring is exactly the same (the little plastic lugs below the red retaining ring below).  but then again, im not convinced that this is the problem anyway as it started again after being filled up.

secondly, after filling it, i watched as i primed it and saw small amounts of fuel being expelled through a small hole next to it, shown below (centre of photo)

that to me suggested the primer worked fine and was just expelling air until filled with fuel.  but….. i just wondered whether this happened prior to topping up, and whether itll still work on half a tank.  just checking, there shouldnt be a cap on it should there?  i assume its supposed to expel air then fuel?

like i say, it lives for now, but im just not convinced that the kit has solved the problem and that for some reason it needs a full tank to start.

cheers