40 HP takes a bit to get on plane

[Sox17]

Engine starts and runs fine, new prop and hub assembly, fuel filter but slow off the start. When advancing the throttle seems nothing is happening about 1/4 of the way then last 1/4 it starts to pick up
Any ideas?

 

[Sox17]

40 HP on a 15' side console sunbird

 

[racerone]

Have you heard this motor run properly on this boat before ?-----If yes describe what happened in detail.

 

[Sox17]

I guess I don't know what properly is for I'm new to boats. I can tell you that all 3cyl have 120 psi, starts right up with ease when I put the shifter forward the linkage moves a little bit but then no movement for about 1/4 of the way forward then the linkage moves more with full throttle. Not much vibration when idle never stalls does get one lane and move nicely after a minute or so just no real holeshot. It doesn't lose acceleration just seems to be absent for a moment

 

[JDusza]

Timing isn't advancing properly or fuel system running too lean.
Throw up the model and serial number for us.
J

 

[Sox17]

1999 Mercury 40HP 3 cylinder 2 stroke SN# OG891444

 

[doyle007]

Is the boat kept in the water? If so, is there barnacle and seaweed growth that is hampering you from getting on plane?

 

[Sox17]

Always towed

 

[racerone]

When did you experience going 25 miles per hour with this boat ?----Last week, last year or never ?

 

[Sox17]

I got the boat used last fall and first time out wouldn't go over 15 mph unless I pumped the choke, I opened it up and found a really nasty fuel filter. The filter was replaced and the carbs cleaned, after that the boat was doing 27 mph with 2 grown men and a kid but it takes a minute or 2 to reach that speed

 

[racerone]

Perhaps try a smaller pitch prop.---Or talk to a dealer about the finer points of selecting a prop.-Perhaps the motor has issues and a compression test may help decide on that.

 

[jimmbo]

Does the ignition advance fully and do the carbs open fully with the throttle lever is pushed to the max? You said it has a new prop. Maybe it isn't the proper pitch for your combo, what is the WOT range for your engine, and what rpm are you getting a WOT?

 

[Sox17]

The PSI on each cylinder is 120 and by my research that is right where it should be. I used s prop selector tool from Mercury. I don't have a RPM gauge.

 

[Sox17]

When at wot I can push on the camshaft and still move the butterfly open. Should the valve be flat?