I've been having some trouble with my 2003 15 hp pull start tiller steer, it starts and runs perfectly for 10-20 min then cuts out
And air leakage before the raw water pump. You'd be surprised how much trouble that can cause.
Ditto, and be sure to remove/ replace the old gaskets.
Which motor are you talking about! On the 4 cylinder Merc, you have an ignition issue--it's dropping a cylinder (or more) under load. I suspect a bad
Parts of the old impeller is probably stuck in water passages in the power head. The best way to remove them is to blast compressed air and water mixture