I have a misfire under load, I have change the plugs and the suspect cylinder coil. I have also changed the plugs side to side but misfire stays with the same cylinder. You can let the spark jump to the plug and is will start to hit better but not perfect. I have not taken a compression test yet. The tractor is only 5 years old and has not been used a major amount. Any help would be great.

Thanks, Dwayne

Dwayne, September 2008

Don't understand the last answer at all. One cylinder is working, so the carb and fuel system must be OK. You've eliminated the plugs (side-to-side swap), so they're OK. Changed coil so (assuming new coil OK), it's not that.

That leaves some mechanical problem with the duff cylinder. A compression test would be my next move. Briggs don't publish figures, but put your finger over the hole (not easy I appreciate) and crank the engine. The pressure should easily blow your finger off the hole. If it doesn't, the compression is too low for reliable ignition.

If compression checks out, start looking for manifold air leaks. If compression is low, check out the valve seats (bore wear is unlikely, and engine would smoke if so).

Hope this helps.

phil_saunders@bigfoot.com

Phil Saunders, September 2008

its not your coils thats doing it it could be your oil level is low i suspect its gravity feed fuel so it sounds like dirt in the fuel system. if it is long reach plugs NGK bpre6s sometimes you might get a faulty one in a batch so it might cause it but sometimes cutting in to fast of gear would make this do that i recomend you take it to specilist to get full service this is best done once a year for longer life for the machine also check oil levels before every use it sounds like you have a few acres need cutting

irish dave, September 2008