Thread subject: Whaler Central - Boston Whaler Boat Information and Photos :: Loss of Power 2004 90 merc two stroke

Posted by mbochino77 on 05/29/10 - 7:03 PM
#1

I have a montauk 170 2004 , I am second owner . When i plane off and cruise at 4200 rpm or less it runs fine , AS soon as I increase throttle above 4200 to 4400 or more it runs for about 30 seconds or less and drops down below 3600 rpm. I can plane off again imediately but i dont know whats wrong. My mechanic rebuilt the fuel pump and cleaned the carbs this week and it runs alot better and smoother but i still lose power at higher RPMS.
Assuming the gas vent is ok can someone tell me how to eliminate the throttle controls from being the culprit. Any other clues before i try my mechanic again . It seems he will have to take it on the lake.

Edited by mbochino77 on 05/29/10 - 7:04 PM

Posted by John Fyke on 05/29/10 - 8:29 PM
#2

If you brought the boat to your mechanic for this problem and it's still happening then I would take it back to him.

Posted by DWinter on 05/30/10 - 5:12 AM
#3

It sounds like either a fuel restriction at hi demand or it's loosing spark at hi rpm. The best thing you can do in this situation is let the mechanic see the problem. I encourage my technicians to "water test" many of our boats with this type of problem. It may be something as simple as a loose ground on a coil, but assuming your mechanic is a Mercury tech, it'll do you and him a lot of good to see the problem for himself.

Posted by sosmerc on 05/30/10 - 6:24 PM
#4

You can run the engine on a second fuel tank/line assembly to at least eliminate the boat's fuel system as the culprit.