losing rpms after planing

Help! I have a 2003 75HP 3 cyl. I have replaced the fuel filters both inline and at the carbs. After starting (no problems starting) and no problems getting on plane, the engine looses rpms. I throttle back and let it idle a minute then it will repeat the process when I plane again. It runs on plane fine for about 2 minutes then slows down. What do I need to check? Thanks for your help.- Charlie

Re: losing rpms after planing

either fuel supply is low or restricted Plugs failing at high pressure or stator is going bad. When was the last time you rebuilt the fuel pump and changed the plugs?One more thing check the gas tank vent for restriction

Re: losing rpms after planing

Thanks for reply. Plugs are new but I have not rebuilt the fuel pump. Could that be it? I did take it apart and blow out the fittings and looked at the diaphram. Didnt look bad. Any suggestions?

Re: losing rpms after planing

do you have an ohm meter to check the stator I don,t think it is that but would test it anyway. being you get up there and then fail shows either a volt problem or fuel problem more than likely. Do you get any hesitation at all ? Or does it just drop off? also did you replace the bulb? Check for air leaks in the lines as well. One more thing Check the tank vent for restrictions. without proper air flow to the tank gas flow will be limited

Re: losing rpms after planing

I do have an ohm meter but I dont know how to check the stator. I have not replaced the bulb or lines but I have not seen or smelt any fuel leaks. How do I check to see that the tank is venting correctly? The motor starts fine and has no hessitation when I throttle up. It gets on plane fine and runs great for about 2 mins then just begins to choke and sputter and slow down. If I let it idle a min then throttle up again it runs fine for about 2 mins then does the same thing again.

Re: losing rpms after planing

I have a 2002 90 hp. Have had none of those problems with it. I did have a CDM that was thermally sensitive whereby one cylinder was lazy till the engine got hot....got past the no wake buoys and got into open water; changed it out and no problems since. I use Sea Foam in every tank of gas, about twice what the can recommends. I keep Sea Foam in the gas as I don't get out as often as I would like and it keeps my engine in proper tune with today's gasolines.

My avatar shows what it will do on a 17' boat; 50+ gps.....never a wrench on the engine other than to replace a thermostat. Impeller is original and can pee 1" or so deep stream at the dock at idle.

Mark

Re: losing rpms after planing

Mark, That 90 looks like a screamer! Thanks for your suggestions. Now its just too darn hot to work on the boat. vI'll get to it when the lakes start coming up again. I have to let the dust die down from the fish swimming up the creek. God bless-Charlie