I have a B&S 12.5 HP I/C Engine Model 289707 Type 015401. I've never had a problem with the engine until I tilted the mower up to change out the steering wheel and shaft. Steering wheel is successfully installed. The engine had a hard time cranking so I adjusted the carb. I replaced the air filter. At this point, I've adjusted the carb all the way down and then backed off 1 1/2 turns. The engine runs fine without the air filter for about 3 minutes. Then a puff of grey smoke and the engine shuts off. There is oil and gas residue in the carb. Any help would be greatly appreciated? Thanks!!

It's possible that while the unit was tilted, fuel may have flowed through the carburetor and into the crankcase and is mixed with the oil. Check the oil, if it smells like gas and appears to be thin, drain and refill to proper level with new oil.

If enough gas enters the crankcase it will mix with the oil and raise the oil level and can cause oil and gas from the crankcase to enter the oil breather and feed this mixture into your carburetor, the extra rich mix of fuel and oil can choke down the engine and stall. Also if your oil is dilluted with gas you can cause damage to the internal componets of your engine if you run it that way.

Thanks for the information. I'll change the oil and plug and see what happens.