I have a 13.5 hp B & S engine on a 38" cut Yardman Mower. Every time a make a turn with the blade engaged the engine stalls. I have replaced the deck belt and thoroughly cleaned all around the blades. The belt does seem a little loose. Is that the problem or is it something else? If so how do I tighten the belt? I can't figure it out.

I suspect that you have a safety switch that is shorting out when you make a turn. Carefully inspect your wiring harness to see if any wires touch and part of the steering linkage including the gear on the end of your sterring column.

Hi,
It may well be the wire that kills the engine when it is put in reverse flopping around.
Peace,
Clarke