the engine on my mower is a briggs & stratton quantum 35, it will rev up if i move the throttle butterfly by hand but not via the throttle cable. the cable & linkage are free & moving & also the arm & linkage coming from the crank-case are free.
I would be greatfull if anyone has got any advice.
Thanks

Dave Lacey, September 2009

The crankcase lever is the engine speed govenor. The operator control on the handle moves one end of the govenor spring. The spring is attached to the govenor arm on the crankcase, and via a rigid link, to the carb butterfly (throttle valve). The tension on the spring (which tends to pull the throttle open - the butterfly should be wide open with the engine at rest and the speed control at 'FAST') is opposed by a force generated by the govenor assembly inside the engine. The point at which the 2 forces balance sets the engine speed. More spring tension = more speed. The speed control on the handle sets the governed speed - more of a cruise control than a throttle. The engine will maintain the speed set regardless of load (within the power limits of the engine!).

What I suspect has happened in your case, is the spring has become damaged/stretched. Some versions of the engine have provision for adjusting max speed (by adjustng the maximum spring tension). If so, no problem, if not, new spring required.

Hope this helps!

phil_saunders(a)bigfoot.com

Phil Saunders, September 2009

I have 2 machines (mine + neighbour) both intek edge engines with the same problem. I would be interested to know what the linkage from the c/case is for and why the throttle lever doesn't move the butterfly valve directly. The best I could do was to bend the arm that has the spring attatched and is moved by the throttle lever out a bit.

Graham Kidd, September 2009