Small Engines (Lawn Mowers, etc.): Briggs and Stratton 40777 21 HP engine., briggs and stratton, hp engine

Question
While mowing recently, the on our rider engine started to make a screeching sound and was followed with a good deal of white smoke pouring from the front of the riding mower from under the hood.  I believe this situation was attributed to the one rather rough area of grass it had gone over - as that's when this occurred if I recall correctly.

Now, when the mower is started, it runs and stays running but the engine will rev up and down, repeatedly over and over instead of the uniform constant purr it had prior. We checked the air filter and assessed that it is not the problem.  Gas seems to be flowing okay - and did not have old fuel in it before this happened.

Again, this is for a Briggs and Stratton 21 HP engine - serial model off of engine 40777.

Thanks.


Answer
Hi Jeremy
The screeching and white smoke sounds like the deck was in a bind and the belt was not turning with the pulley and burning, not an engine problem. Check your gas cap to make sure it is venting properly and don't put any additive in the fuel. If this problem continues, remove the carb and clean all jets and ports as well as the needle valve. Hope this helps.