My boat has been starting cold well, after running the engine for 20-30 minutes and then turn it off, the warm start a few minutes it hesitates to start unless you give it gas. I used a fuel pressure regulator and the pressure is good while the engine is running, then when I turn it off the pressure quickly drops to 15psi. The injectors are good, I have replaced the low pressure fuel pump and the fuel filter is good.

Today I took the boat out and it hesitates, then a second or two gets going but with less power. The engine is smoking more as well. When I throttle up the engine at the dock it runs and sounds fine but when I try to pull up a skier there is low power and a weird wapping sound. The spark plugs are good as well.

I think it might be the high pressure fuel pump. Any info. would be great.