7hp B&S runs rough then stalls?

Me again. Check the air filter as mike w and I both suggested. On my partner's mower the crankcase breather feeds into the air filter, which can become saturated with oil which then gets drawn into the engine and smokes. A really good wash cured this on my machine - at least till the air demand balance spring gave up...

Dunk
October 2004

sounds to me like you have a air leak in one of your carb mounting gaskets.also you may have a dirty carb or a leaking float valve.i would contact sears and see if they would check it under warranty since the mower is not old.sears usaully has a good warranty policy.depends on what color smoke it is if it is white smoke you have internal problems in the engine which could be a simple valve adjustment.if it has overhead valves they probally need adjusted.if smoke is blue not good it is oil make sure the oil is not over full make sure no gas is in oil carb may be leaking gas into the motor.if the smoke is black looking the problem is in the carb the engine is getting to much fuel.you also might have a weak coil if it does it worse the longer it runs which you would get alot of missing.although i beleive your problem is carb or a valve adjustment if it has overhead valves

mike w
October 2004

Oops, nearly forgot. Get a new primer bulb too, just to be on the safe side

Dunk
September 2004

I think that the answer lies in two springs, one large one small and delicate, that control the gadget that balances the engine speed to inlet vacuum, preventing the engine from running away with itself ince the throttle is effectively an on/off switch.

On my partner's machine, which she has had a goodly length of time, I found that the small spring, which looks as if it's wound from 1 amp fusewire, had sheered, and the bigger main spring isn't quite up to the task of accurate control.

Not sure where you'll find these springs on your machine, but on a British Hunter mower I had to remove the airfilter (give it a good clean while you're at it!), and underneath on the side nearest the engine block is the largish spring and this diminutive little sucker, both attached to what looks like a throttle linkage. Check the small spring hasn't become detached. If it has, you may need to re-bend the hooked end and re-attach it to the slot in the linkage, which is the only place it will go without tensioning it, and slip the looped end over the circular post (which looks like a really tiny ringbolt or curtain wire support). If you do have to reprofile the end of the little spring you may find the mower runs a bit fast, but not enough to be life threatening. Both springs should be untensioned at start up

I hope that all makes sense. It should when you have a poke around the engine/airfilter area and find the twin springs/linkage. If the engine hunts, ie won't find a constant running speed, you'll see the linkage moving back and forth, alternately stretching and releasing the tension in the springs. Those are the springs you need to take a look at.

There you go. Saved you some cash if it works, since my local agent charges about 50 quid (about $85) to sort out this sort of thing.

Dunk

Dunk
September 2004