Craftsman Tractor Blowing Smoke, Backfiring, and Runing Poorly
We have a Craftsman lawn tractor with a Briggs 15.5 I/C Platinum 28N707 engine. Never had any engine problems, but this year after servicing (oil, plug, and cleaned filter) - the problems began on 2nd cut after servicing. Here are the observations:
- Blows white smoke when heavy load is applied (engage blade for example).
- Backfires when idle speed is low.
- Runs very rough at low idle (but became better the longer I ran the tractor).
I did some diagnosis last night and installed another new plug. I did find that there was too much oil in the engine. It was overfilled by about a half quart. The mower ran fine at normal throttle, but would not run well at low idle (missed, almost died, etc.). The mower would smoke intermittently under load. The more I ran the tractor the better it ran and the less it smoked (even when under load). It ran fine at normal throttle for about 15 minutes up and down grades. The low idle speed operation improved over time and I was able to get the mower to run at low idle after a while. When I pulled it into the garage it "dieseled" and backfired again.
Can the oil level cause this type of behavior? I am going to do a compression test on the mower tonight, but if the fault is related to service I did (oil) - I find it strange that it mowed fine one time (full yard cut), before it really began to act up. I find it hard to believe it has lost time (shear pin) because of how normal it was running at throttle. BTW - I did NOT turn the mower over on its side to change the oil.
Any help would be appreciated........