home Fix label Garden Tools label_important Lawn Mowers category Briggs & Stratton

Mountfield Laser Omega Running fast and slow?

My mower is fitted with a briggs and stratton engine and has just started running a bit rough, it runs fast then slow like its regulating itself that way. Its never happened before, when i turned it off it became difficult to start and normally it starts first time, any ideas?

Jay, June 2008

home Fix label Garden Tools label_important Lawn Mowers category Briggs & Strattondone

just had same problem. you do need to take the tank off or least loosen it. but mine was a broken carb manifold. was hiden by all the grass dabery. cleanned and washed out the carb and primers too while it was off.

ash, March 2011

Thanks guys, just to let you know that I replaced the diaphragm and the problem is now fixed. A great site! thanks again. Jay

Jay, September 2008

Im pretty sure its the diaphragm too, jetting out the carb did not cure it.

Ive struggled to get the Carb off the mower, there are 4 bolts holding it down which i have removed but still can not get it off, do I have to remover the fuel tank?

Also where can I get the new diaphragm from?

Jay, September 2008

Hi its more than likely the Diaphragm it sits between the carb and the fuel tank
Hope this helps

mowerman, September 2008

If it's a carb-on-the-tank model, I'd bet money you have a faulty diaphragm. While the carb is off for cleaning, you might as weeel replace it. Costs pennies, and faults are not always visually obvious so replace as a matter of course.

phil_saunders@bigfoot.com

Phil Saunders, June 2008

Thanks John, I will give it a go!

Jay, June 2008

Your mower has a carburettor problem - namely the slow running jet is blocked. To compensate for this, the governor system calls for the motor to speed up....and then slow down again. A good clean of the carb. is needed here - not difficult but its best to use a proper aerosol carb cleaner and compressed air if you have it.

John, June 2008

link Click here to see other fixes for Briggs & Stratton.