I recently restored a 1979 citation 300 with a 294 twin. The sled ran great after replacing the plug wires, caps, and plugs themselves. I was riding it the other day around the yard and lost a ton of power and the motor began skipping and backfiring. I have narrowed it down to the MAG cylinder and have checked the timing and points more than once. does anyone have a suggestion as to what would cause this sudden change in operation?
I have clear tubing on the fuel pump pulse line and when it backfires I can see flame shoot out the case toward the fuel pump. Like I said, this was an instant change and I dont know what caused it. I still have spark on the plug, and can tell when the cap is pulled the engine slows to a true single fire. This all seems to be worse the more open the throttle is held or pumped.