Own a 2003 Manitou pontoon with a four-stroke bigfoot with just over 100 hours. Lately have a high pitched constant alarm going off at snail speed, with a motor shudder the minute I try to increase speed. Water stream is strong and steady from motor. New water pump, and oil just fine. Any ideas what's going on? I am at a loss with the owners manual for any help. Thank you!
Sounds like a low pressure fuel pump problem to me ( your engine has both low and high pressure pumps). Or, it might be a bad alarm module. Either way, I have no "quick fix" for you. Have a certified technician inspect the engine.