Lawnmower fix broken governor
Satan, a Rover Sprint 373 Lawnmower, with a Briggs and Stratton ‘Easy Start’ engine got his name because from NEW he would never start easily – only ONCE did Satan start easily and that was the day I took him back to the shop to complain!!
Here’s the misleading advert –
Our previous mower had a vertical pull cord. I could put one foot on the mower and yank up and easily start it, so of course when it was time to buy a new mower, I bought another Rover, not realising that the pull start was now aimed backwards.
The mower is 15 years old now and has only ever run for 10 minutes at a time, to cut the small amount of grass around the pool. He’s started showing his age. Recently he would only run for 3-4 minutes before dying.
Investigation showed that the rubber primer bulb was completely sucked in and research suggested the carburettor to fuel tank gasket has dried out and needs to be replaced.
Before I could get to that job, more problems turned up. The only way to start this ‘Easy Start’ mower is put the lawnmower on an incline, prime 4-6 times with firm pushes of the bulb, then pull the starting cord as hard as possible while shoving the mower down the slope- also as hard as possible. With all that, it barely starts.
I started the mower, intending to quickly cut as much grass as I could before it stopped, and when I released the starting cord it must have caught up in the blade of the governor and jammed. There was a horrific shrieking noise, as if the engine had seized. I rotated the blades backwards and unjammed the cord, but the governor lever, which is connected by thin springs, was loose.
I started the mower again and it ran at full throttle. It was quite impressive, never before had Satan sounded so eager!!
It was revving so hard that fuel began to spray out of the three vent holes in the fuel cap!! I switched it off quickly.
I’ve assumed that the blade of the governor is broken. I could take everything apart and fix it, but the mower is old, it’s only a small amount of grass to cut. I decided to connect the throttle directly to the butterfly in the inlet manifold and take over control of the throttle.
It was very simple, using traditional Aussie Bush Remedy methods –
FENCING WIRE !!
I removed the springs, bent a piece of thin fencing wire with a loop for adjustment and connected it to the butterfly lever and the throttle cable.
I made sure that the throttle would totally close, because that’s the only way to switch the mower off. Started the mower and – YES!! I had control over the throttle. I mowed the grass and although the rubber bulb sucked right in, the higher revs I was using allowed enough fuel to be sucked into the engine for it to keep running.
I noticed that where the grass was a bit higher and thicker, I had to increase the throttle a tad and reduce it once back on lighter grass. Just as I expected. I have new respect for the clever governor system and I guess I have just taken the evolution of motor mowers back 30 years. But I’m happy with the result and now more encouraged to fit a new carby gasket.Share