Boat Issue

[sunkee]

I have a 99 17' Tracker with a 60hp motor. I put on a new prop but cannot get the boat on plane. It revs up fine and then hits a spot where it sounds like it is cavitating and then revs back down and only runs 50% power. Any ideas what might be my problem?

Thanks
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[HeberCreeper]

Does your new prop have a different pitch vs. the old? Maybe you're over revving the motor and bouncing off a rev limiter??
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[fsh4fun05]

Yep. We are going to need some more information on this one. What brand motor, what size prop, type of prop, what pitch, what kind of hub, what rpm's are you pushing, etc.
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[sunkee]

Possibly. I got the boat from a guy who trashed the prop at utah lake last year. Matched the new prop as close as I could to the old one. I had the prop doc look at it and said it definitely is not a prop issue. Rev limiter? What can you tell me?
Thanks
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[ReelMasta]

Motor type and size?
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[sunkee]

1999 Mercury 60 horse on a 17' pro deep v tracker.

Thanks guys
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[HeberCreeper]

2 stroke or 4? What kind of RPMs are you getting? You could be dropping a cylinder (no spark) with a bad CDI unit.
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[sunkee]

The motor is 2 stroke. Pitch is 11 and 11-1/2" prop diameter.
Not sure on what rpms I'm getting as the tach is not hooked up.
Seems like it runs fine at low rpm but when you try and get on plane
It revs high quickly like it's cavitating and then runs like it's only firing on 2 cylinders.
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[a_bow_nut]

I refurbished a boat that had sat for twenty years this spring. When I took it to the lake it was doing the same thing. I ran a couple of tanks of gas through it with a can of sea foam in each tank of gas and it runs much better now. If your boat sat for awhile with gas that has ethanol in it the ethanol can form some nasty stuff that the carburetors don't like.
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[Outfishing13]

Make sure that the water pump is in good working order. Make sure you are getting a good stream of water from the pee hole on the back of the cowling. Another problem this can be is overheating and the ignition system automatically retards the timing and reduces the speed.

Over heating can be the water pump or over propped.

You can call or email Tracker Boats or Mercury Motors and they will suggest a prop of the right diameter and pitch. Do you still have the old prop? Inside the hub on the part that mounts on the inside against the lower unit you should be able to see a number on the prop. That will have the make and model number and often the size of the prop.

If the prop has to much pitch (to steep) then the 2 stroke will have problems getting enough revs to get out of the hole and will start to overheat. Then the automatic overheat sensor kicks in and slows the motor down (by retarding the timing).

A 2 stroke motor with the proper size and pitch should rev right up and get you going. Over propped it will stall and overheat.

A little research should help you out. Hope this helps.

I love boats, but only when they run right.....[]
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[sunkee]

Yes this boat sat for 3 years so that could be one of the problems. The water pump is good with a steady stream pumping out. I had the prop sized based on the motor from mercury dealer-so my impression is it's not a prop problem.
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[wiperhunter2]

Does the motor have power tilt? If so, have you tried to adjust it the tilt down when it starts acting up, like you described?
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[sunkee]

Yes it has power tilt and I tried raising the motor while it sounded like it was cavitating and it just throttled down the engine.
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[ReelMasta]

PM sent
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[utwalleye]

The 11 pitch sounds a little small for the altitude of slc valley. I ran a 17 pitch in the valley and when I went up to strawberry I had a hard time getting on plane, I put a 15 pitch on and got on plane right a way. But one thing though you really need that tach hooked up, it will tell you everything. "It revs up real quick" sounds like the pitch is too small.
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[southernbass]

Here's a little suggestion.take a couple of friends with you(2 will work) havr them sit in the front of the boat to get it to plane, if your motor runs great while it's plane then its probably a trim issue, motor or prop.if it still runs ruff try cleaning the carbs if you have any on that size motor.
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[wiperhunter2]

[quote sunkee]Yes it has power tilt and I tried raising the motor while it sounded like it was cavitating and it just throttled down the engine.[/quote]

If that's what is causing the problem and not something else, then you want to lower the engine not raise it. Raising it will make the problem worse and you will loose power.
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[sunkee]

Thanks everyone for the help. I'll try everything suggested and I'm confident the problem will get resolved.
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[lakepowellnut]

Everyone has made some great suggestions. Make sure you haven't spun a prop hub. Fixed a boat last year with same problem. Turned out to be a spun hub.
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[Fowl-Hook]

Question: Can you visually determine if a prop hub has spun or broken loose. Is the hub designed to break loose and still be functional after without maintenance or repair?
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