I have twin 50hrps, the boat belonge to my Grand father, it sat in his barn for years, I changed the water pump impellers, the temerstats, blown air through the power heads, but they both crank up pissing then once warm Quit! get hot set off the alarms and I shut them down. I have done everything I can think of short of removing the power head? I have even put a water hose to the water intake inside the housing with the lower unit off and the water flow looked normoral