mercruiser 5.0 not getting full power

[2long]

I have a 1999 Chapparel sign 300 with twin merc 5.0 efi. the boat has been has been sitting for about 2 years. motors has about 200 hours. started repairs in april and still not running properly. Motors starts up fine and runs at proper temperature, but will not go above 2500 rpm (both motor). Boat will perform a little better with strong head wind and heavy chop, will then get to about 2800 rpm. Fuel tank has been drain and replaced with fresh fuel, New fuel pumps, new injectors, new filters, new alternators, new risers and elbows, new idle control sensors, new circulating pumps, water pump, plugs and plug wires. Mechanic has check motors with computer and found no codes. Another mechanic mentioned than is motors sit too long computers need to be reprogramed??? When I checked with mercruiser they said this was false. Does anyone ever encountered this problem or have any suggestions??

thanks

 

[Bondo]

Re: mercruiser 5.0 not getting full power

or have any suggestions??

Ayuh,.... Had to believe Twins are runnin' Exactly the Same,..??..??..??
But anyways,...
They were run Dry at some point,+ the Shutters burnt up,+ finally fell down into the exhaust passages,...
They can breathe In,+ Can't breathe Out....

Maybe.....

 

[180shabah]

Re: mercruiser 5.0 not getting full power

Put a vacuum gauge on them and run again. If the exhaust is restricted, the needle will drop lower and lower while the throttle is wide open.