1992 250hp low rpm at wot

[richd]

Just had a rebuilt powerhead installed on the port side, runs ok until about 1400rrpm and then rpms will go up and down with added throttle till i reach a certain speed and it seems to catch and pick up more speed. When i give more throttle to the starboard angine , the port engine will increase if i push it. Boat gets on plane,both engines about 3500 rpms. If i throttle down ,the port engine rpms slow down to 1400 and sometimes wont go any faster.
Appreciate any ideas...

[Ken]

rich,
I would suspect clogged carbs or weak fuel pump(s) - you have three.
If your fuel pumps are at least five years old, I would replace them. Some owners do this just as a preventive maintenance.
Try a shock treatment with SeaFoam or RingFree to de-carbonize the motor and clean up the fuel system including the carbs - sometimes this works.
If not, try to remove all the carb jets you can get to, esp. the high speed jets. Squirt some Berrryman's Chemtool into the orifices.
If none of the above works, then time to remove carbs, teardown, clean, and install a carb kit.
Also, you need a 10 micron fuel filter/water separator between the fuel tank and your motors to counter the effects of ethanol blended fuel.
Good luck [img]smile.gif[/img] ,
Ken K

[richd]

I will try all that you suggested. The engine in neutral will rev to over 4000 rpms no problem but in drive its a problem. Do you still think its the carbs or the fuel pumps? The engine is a 1992 250hp, just replaced but using my old fuel pumps i guess.
thanks

[ August 02, 2006, 10:31 PM: Message edited by: richd ]