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Mountfield Ride-On Mower

Discussion in 'In the Garden' started by Treeze, 19 Apr 2021.

  1. Treeze

    Treeze

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    Hello - hopefully someone can help - we have a Mountfield ride-on mower (about 2 years old) which keeps cutting out at high revs. Ticks over fine on low revs, but stick it into high revs, it runs for a little while (30 secs to a minute) and then just cuts out. My partner has cleaned the carb, taken out the air filter, but it still does it. Could it be the dodgy battery or plugs? Any help gratefully received because I did my daily number of steps yesterday with the push mower!! Thanks in advance
     
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  3. Burnerman

    Burnerman

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    By all means try a new spark plug but the chances are its fuel starvation.....can you tell us which machine it is?
    When it tries to pack in, give the engine some choke, if possible, and see if it picks up again.
    John :)
     
  4. Treeze

    Treeze

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    Thanks. I'm pretty sure it's a 1530H, but I'll confirm for sure later. It doesn't give you much chance to give it some choke, it just stops. It doesn't sputter first, it just dies.
     
    Last edited: 19 Apr 2021
  5. Burnerman

    Burnerman

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    That machine is likely to have Mountfields own engine, against the earlier Briggs and Stratton.
    No problem though, the carburettor will have to be removed for a clean, and an aerosol of carb cleaner is essential.
    Post a picture of the carb if you want to have a go!
    John :)
     
  6. Treeze

    Treeze

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    OK, thanks. I'll check the machine when I get home. Now I've started the thread, I'll hand it over to my partner as he's the technical one. He did clean the carb yesterday, but not sure if it was with carb cleaner or a quick rub on his shirt...! Anyway, I'll be back on here later with an update. Thanks again.
     
  7. Treeze

    Treeze

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    It’s a 1538M. Fuel line was blown through, fuel filter was removed and replaced temporarily with a piece of pipe to eliminate a blocked filter, carb was removed and jets checked, float valve cleaned. I agree seems to be starvation but I can’t see how, all looks ok. I haven’t removed the plug yet. The battery is not good, was having to jump with leads to get started. Ticks over great, but bring up revs runs for short period then cuts out.
     
  8. Burnerman

    Burnerman

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    Once the engine has started, the battery condition has nothing to do with your problem.
    Spark plugs failing under load and heat isn’t unknown so always best to fit a new one, just to rule it out.
    When you overhaul these carburettors it is essential to use a proper carb cleaner in aerosol, I have the luxury of a compressed air line too.
    Always look for rust deposits in the float chamber before you go any further. I’d take great care looking at the needle valve operated by the float, followed by the main jet and the emulsion tube directly above it but its only a cleaner plus compressed air that will really do - just blowing through jets with your breath isn’t enough.
    The fact that the engine runs for ever at slow speed but dies at high revs, where its using much more fuel has to indicate a fuel shortage at this time.
    John :)
     
  9. Treeze

    Treeze

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    Thank you. We’ll give the carb another go. Fingers crossed
     
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  11. SEBB52

    SEBB52

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    My mower does the same thing, I was cutting the lawn one day when it just cut out, I fitted a new plug, air filter, fuel filter, flow from the tank, petrol OK works in my push mower, dismantled the carburettor twice. start some times oK or struggles if starting after its cut out managed to get it to run on tick over for 4 mins max or about 1 min on fast speed so all the symptoms lead to fuel but at a complete loss of what to try next.
     
  12. Burnerman

    Burnerman

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    In this instance I'd pay particular attention to the flow of fuel to the float chamber of the carb.....there should be a good flow of fuel after the filter (pipe disconnected) and then the needle valve, controlled by the float. If it's a Briggs motor, look up for a red circle of rubber where the needle valve seals onto.
    Occasionally these swell and fuel supply can be restricted.
    John :)
     
  13. Treeze

    Treeze

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    Even though we had already done the things suggested and re-done them, the last resort was to get a new battery - bingo - the problem has gone away. Thanks for all the responses and suggestions.
     
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  14. Burnerman

    Burnerman

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    Hmmm!
    Not really convinced but delighted that it's sorted.....unless it has the electric shut off on the carb base and the battery terminals were slack.
    Enjoy the machine!
    John :)
     
  15. Lower

    Lower

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    I don't think that mower has an alternator so the battery has to have a decent charge or it won't be able to provide enough power to keep the plug sparking at higher revs.
     
  16. Burnerman

    Burnerman

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    Has it got an external coil rather than a flywheel magneto?
    John :)
     
  17. Lower

    Lower

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    Pass, looks like you know more about it than me :)

    However, i have a mountfield ride on with a briggs and stratton engine. If the battery on mine is flat i can jump start it but it will stall as soon as the booster battery is disconnected.
     
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