HELP!! 2004 Speedster 200 fluctuating rpms.

[Asvetz]

Hi everyone. I am new to the boating world and forums. I recently purchased a 2004 speedster 200 with the twin 155 engines. NOT supercharged. The guy I bought it off of took me for a quick test ride and everything ran great but now I'm finding out after about 20-30 minutes on the water the port side motor will start fluctuating rpms. If I bring it back to idle then rev that engine it feels like its lagging or theres something in the impeller or something. I checked all of that and there isn't. Long story short I've done everything from changing spark plugs,oil,fuel to swapping fuel pumps. I took it to the 1 of 2 mechanics in the Pittsburgh area and he ran diagnostics on it and said its not kicking and codes or going into limp home mode or anything like that so after a month there he changed the fuel pump core and gave it back to me. Its still having the same issue. No lights are coming on, I've checked engine temp when the issue occurs and both engines are running the same. If I remember correctly they were about 148 degrees. Im wondering maybe the wiring harness? Wires are getting hot and making it fluctuate after 20 minutes of running fine. If I sit on the water for 10 to 20 minutes the engine will fire right back up and run great again for allotted time then start the same issue over again. Is there anything I can be over looking? Any info would be greatly appreciated. Im going crazy over this problem.. Thank you very much for your time!

 

[pete63]

just wondering if the impeller/drive shaft bearing starting to seize. might be worth checking the pump/impeller out.
check/swap the air filters

 

[Asvetz]

Hey Pete. Thanks man. I looked into the air filter and it doesn't have one. Just a air box. Not much there but the impeller is something I was thinking of also. My only question to that is would that happen like clock work every time? It will literally run perfect for 20 minutes then start acting weird. I would think if the impeller was messed up or anything in the propulsion system for that matter I would know as soon as I turned the engine on? Or can that stuff heat up also?

 

[XP 787]

Try swapping rectifiers.

 

[Asvetz]

Ok. Do you know where they are of the top of your head? If not I'll get in the book and check it out. Tanks man.