Mountfield SV 50 help.

[Matt Clueless]

I have recently filed the fuel tank of my lawn mower with water. On realising the mistake I drained the tank and refilled if with the correct fuel.
It now doesn't want to start.
Any help as to how I fix this would be most gratefully appreciated.

 

[Burnerman]

SV150, I guess?
With this one, you need to remove the carburettor float bowl (1 10mm bolt at the bottom) and tip the water out. At the same time, allow any contamination to run through the carb, onto a rag.
Pop the float bowl back on and you should be ok.
John

 

[Matt Clueless]

Great thank you kindly John. I'll have a go at this tomorrow.

 

[Burnerman]

A pleasure! Above the float bowl is a rubber ring in a groove. There's a fair chance it will stay put but if it drops down, carefully push it back into place. The rest you should be able to leave alone.
John

 

[Matt Clueless]

Had a go at this today and it now starts fine. The carton was full of white crust and lots of water. I actually took it off and have it a blast with the missus hair dryer!. The air filter sponge was also slightly damp. The mower now runs but only on full throttle up to the top so this includes the choke. I put fresh fuel in so it shouldn't be this. Any suggestions greatly appreciated.

 

[Burnerman]

Aha....so now it only runs on full choke, I guess?
How long was the water allowed to sit in the carburettor? You'd be amazed at the speed at which things can corrode.
No matter - how do you feel about removing the complete carb, and going for a strip down? 10mm spanner and a screwdriver with a 4mm flat blade would help!
The problem is, you have some sort of blockage in the main jet and/or emulsion tube.....these reside in the same tube that the float bowl bolted on to.
Nothing to be scared of, really - but an aerosol of carb cleaner is best to have standing by.
John

 

[Matt Clueless]

Great thanks John. I took the Carb off today and it had lots of white crust stuck to the inside. I assume this is corrosion. I'm guessing youtube will have a how to on cleaning it. Do you know of a retailer for Carb cleaner? Thanks again.

 

[Burnerman]

Carb cleaner in aerosol is available from motor factors - it contains toluene and can dissolve most varnishes and so on that you find. Take some time to clean the outside first!
With the carb upside down, take the float chamber off to expose the plastic float. This can be removed by pushing its pin across.....it will bring its needle with it, so careful there.
With that out of the way, use a screwdriver to undo the main jet (brass with a hole in it) and hopefully the emulsion tube above it too. Feel free to poke any holes you see with fuse wire.
Squirt the carb cleaner down every orifice you can see...there may be a spring loaded idle jet screw, and if you remove it, count how many turns you can turn it in first before taking it out.
Enjoy - I hope you sort it, but a compressed air line sure helps!
John

 

[Matt Clueless]

John, took the Carb apart last night. I'm sure theres less muck in a brothel! Gave it a really good clean out. The fuse write was a great idea. Put it all back together and started it this morning. Runs great many, many thanks.
Not sure if others can read this but a bit of advice if you decide to do this yourself.

good video to get you started if like me you are clueless.
Put an old sheet on the work bench this will keep everything clean and make it easier to spot little screws and springs.
Halfords sell carb spray is about £3 for a can which is more than you need.

WEAR A PAIR OF SAFETY GOGGLES old ones. The cans are highly pressurised and if you get the stuff in your eyes it burns. Old ones because the spray degrades plastics so they won't be any use after.

Don't put all the bits in a plastic container (old yoghurt pot) to soak them. The spray with melt the plastic.

Finally it's not that hard to do (if you have great advice, thanks John) so give it a go.

 

[Burnerman]

Well done you! I'm still not sure why water was added in the first place (wrong can maybe)
Very pleased alls well.
John