Mountfield Hunting/Governor issue?

[Bat135]

Hi

I have a really annoying issue with my Mountfield sp421 pdr roller mower.

It starts and runs fine but when it tries to hunt/adjust air? using the automatic choke/governer that's spring operated it stalls every time. It's almost as if the hunting spring mechanism hits resistance and doesn't settle or correct itself. It just moves to adjust the choke/air or whatever it's for and then stops in one position stalling the engine. It moves freely with my finger? It's almost as if it's getting stuck or not springing back properly to find its position?

I have changed the carb to a brand new one and still the same issue?

So it's something to do with the automatic hunting / choke mechanism or governer movement.

Any ideas? It's doing my head in.

Kind regards. Paul.

[Mick]

Paul, when you say hunting, you mean the revs are just surging up and down until it finally stops?

[Bat135]

Yep

When I initially start it it's fine. Idles.

But as soon as I push it or put it under load by cutting the small metal lever connected to the governors springs starts to move changing the revs briefly then it stalls. On new carb aswell.

Happens everytime. Can't use it like this??

[Bat135]

It's almost as if the governor setup is getting stuck and not settling into position. So it just stalls. It used to just go back and forth and settle. Now it just goes back and stalls. The L shaped metal but connected to the pairs of springs that controls revs. But it moves freely with my finger.

[Mick]

Sound like the carb is gummed up and needs a clean.  It will basically start up and then stall with the throttle opening up to full.  That's what happens when the engine is starved of fuel. 

I think your starting point will be to remove carb and give it a thorough clean.  Also make sure you're using fresh fuel, and not stuff left in the can from last season. 

[Bat135]

Thing is I replaced the carb. As it was doing this before? So it can't be gummed carb. It's literally brand new?

[Yorkshiremike]

  Wonder if the governor needs resetting sort of thing.

[Mick]

I would say if it starts and runs at all it's not the governor. If anything it would either over rev, or not start at all or just idle if the governor was set incorrectly.  The fact that you see the throttle move by itself indicates the governor is working.

If you have a can of spray carb cleaner, try to keep it running by giving it a few shots of spray in the intake and see if it continues to run.  If it does then you still have a fuel issue.

[Bat135]

Tried carb spray already.

Doesn't fix it.

[Bat135]

Should I send a video??

[Mick]

A video would be useful, do you have somewhere to post it like youtube or facebook.  This site won't take videos due to file size limits.

[Bat135]

The governer doesn't move at all when I start it. And it starts first time everytime. It's only when it starts to move... whilst hunting / revving does it stall. Which is usually about a minuite ir so after starting it or immediately when I start cutting the lawn.

I can see the L shaped thing that adjusts the revs and is connected to springs move... the revs go up. Then just before the revs go down it stalls.

[Bat135]

I will try and post a video shortly. Or a link to one I can host elsewhere.

Can't really describe what I mean any other way.

It's like it starts to hunt when under load (ie, cutting grass) then it stalls. Can the L shaped governer but. Basically an L shaped piece of metal with springs attached get stuck? As that's what it seems like it's doing. Yet it moves freely wuth my finger???

[Bat135]

Thanks for your assistance by the way.

[Mick]

Thanks for your assistance by the way.

You're welcome, and welcome to TGMForum by the way I forgot to say this in my first reply.  It's always tricky trying to pinpoint problems when you can't see of hear the machine.