Mercury 2001 150hp loss of speed power

[vic5758]

I have mercury 2001 saltwater series 150 hp carb twin engines that are not performing like they did last year i get 25 mph at 5600 rpm when last year i was getting 45 mph 5600 rpm and motors stall at full throttle before boat gets on plane..

Motor on port side is smoking allot (white smoke) during (cold start and hot start) and hard to start when hot i have taken out plugs and looked at them and top of pistons for the steam clean look indicating water in cylinder but everything looks good except for some carbon build up..

This is what i have ruled out so far
compression test 125psi across the board on both engines
spark test on both engines jumping 7/16 gap

Any help would be greatly appreciated

 

[Chris1956]

Re: Mercury 2001 150hp loss of speed power

Vic, Your post is confusing. Are you seeing 25 MPH at 5600PRM on both motors? If so, and last year you got 45 MPH at that RPM, the props are not working properly. Maybe you spun one prop? As for the white smoke (steam). Sounds like a bad head gasket, however, it could be worse. I am not an expert on that motor, so I will let the experts help on it.

 

[vic5758]

Re: Mercury 2001 150hp loss of speed power

hey chris, i indeed am getting 25-28 mph on both engines.. If i had a blown head gasket wouldn't the plugs have that steam clean look??

 

[vic5758]

Re: Mercury 2001 150hp loss of speed power

any help would be greatly appreciated..