Brigs & Stratton Lawnmower engine won't stop!

[eveares]

I have a self propelled petrol mount-field lawnmower that I have had since 2004, and for the first time last week it would not stop when the throttle was let go. I had to push the throttle cable in by hand very hard to just about stop it.

At first I thought it stops by friction from the pad what brushes up against the flywheel, but now I think the thin wire what attaches to the brass bit, shorts the coil/armature out to ground when the throttle is let go, thus stopping the engine.

Below is a couple of pictures of the stopping mechanism what I have cleaned up. Can this part still easily be got if it needs replacing, or do I just need to bend the brass pointy bit down with force?

stopping mechanism

• eveares
• 21 Jul 2016

Close up of ground switch

• eveares
• 21 Jul 2016

 

[Burnerman]

You are correct, the engine is stopped by the grounding of that low tension wire and the problem is the brass point isn't wiping onto the other contact. Careful bending should sort it!
John