Outdoor Power Equipment and Small Engines - B&S 16HP Vanguard only fires on one cylinder

Hey

I have this piece of garden equipemnt with a Briggs 16HP Vanguard powering it. The problem is that the engine isn't doing so much of the powering nowdays.

The problem seems to be that it fires on only the first cylinder. I can sometimes get it to fire on the second cylinder as well if I set the throttle to slightly above idle. But it will only run on both at that speed and on idle. If I try to open the throttle more, the second cylinder dies again. I've tried running it full power under load, and well sometimes it's just chugging along on one cylinder and sometimes it will backfire like crazy, shooting flames out the exhaust.

I've gone though the carb, and it seems allright. I also took the valve covers off to see if any valves were stuck, wich they were not. I've tried replacing the spark plugs, and that didn't solve the problem at all. The ignition seems to be working because it sparks very reliably on both cylinders. I've tried bending around the wires a bit and tapping the coil with a piece of wood but nothing happens.

Where to go from here? :help:

I would suggest checking the spark with an inline spark tester, that can be used while the engine is running. This way you can see if your loosing spark. You may have a weak module that quits firing under compression.

Yup, that's probably it. I tried decreasing the gap on the sparkplug, and when I did that it seems it has enough power to spark. It still don't run well on idle but at higher speeds it suddenly works well. Stilla gonna get a new coil. :)