YAMAHA 2002 115 2 STROKE

[NEIL JOHNSON]

HEY GUYS CAN YOU HELP ME OUT WITH THIS PROBLEM?
I HAVE A NOV 2002 115 HP YAMAHA 2 STROKE WITH 100 HOURS ON IT. I SUDDENLY HAVE LIMITED FORWARD THRUST AND CANNOT GET ON PLANE WITHOUT THE ENGINE REVVING ALL THE WAY UP TO 5800 RPM'S. AT SLOW SPEEDS SHE MOVES AHEAD FINE UNTIL I GET UP TO ABOUT 2800 RPS AND OVER. THOUGHT I HAD A SPUN PROP SO I REPLACED IT WITH THREE DIFFERENT ONES WITH NO SUCCESS. IT SOUNDS LIKE I AM DROPPING OUT OF FORWARD GEAR INTO NEUTRAL AT THE HIGHER RPM'S.
ANY IDEAS WHAT ELSE IT COULD BE???
I CANNOT FIGURE IT OUT. I CHANGED THE LOWER UNIT OIL TO BE SURE IT HAD ENOUGH FLUID.

[LuckyLady]

Originally Posted by NEIL JOHNSON

HEY GUYS CAN YOU HELP ME OUT WITH THIS PROBLEM?
I HAVE A NOV 2002 115 HP YAMAHA 2 STROKE WITH 100 HOURS ON IT. I SUDDENLY HAVE LIMITED FORWARD THRUST AND CANNOT GET ON PLANE WITHOUT THE ENGINE REVVING ALL THE WAY UP TO 5800 RPM'S. AT SLOW SPEEDS SHE MOVES AHEAD FINE UNTIL I GET UP TO ABOUT 2800 RPS AND OVER. THOUGHT I HAD A SPUN PROP SO I REPLACED IT WITH THREE DIFFERENT ONES WITH NO SUCCESS. IT SOUNDS LIKE I AM DROPPING OUT OF FORWARD GEAR INTO NEUTRAL AT THE HIGHER RPM'S.
ANY IDEAS WHAT ELSE IT COULD BE???
I CANNOT FIGURE IT OUT. I CHANGED THE LOWER UNIT OIL TO BE SURE IT HAD ENOUGH FLUID.

What did the gear oil look like, burnt? Excessive metal shavings?
If you had a problem with the gears, you would usually not movement at all and would most likely hear something coming from the lower end.

100 hrs on a 2002 is light, and most likely is fuel related.

I would change the high & mid pressure filters ( not the visable one when you remove the cowling) they are recommended to be replaced at a 100 hrs.

Otherwise maybe a bad fuel pump and i would recommend taking it to a dealer to have it checked fuel pumps vary and are not cheap to change out some range depending on models $600-$1200.

Just change the filters before hand to save yourself some bucks, because if they find low fuel presure they are going to want to change them.

Also before you change the filters you should have a fuel water seperator inline dump it in to a clear container and look for debris and run it again dump it to be sure there is nothing in your fuel.

Hope this helps....

[HOLWACHAGOT]

If it is a fuel problem I seriously doubt the engine would wind up smoothly. Something gear related or something causing the prop to cavitate possibly. Does the engine sputter or does it just sound like it is winding up and not propelling you forward at speed? Sounds very likely that you have some sort of cavitation issues or gears are slipping. Have you checked the hull of the boat?
Has it ever worked properly FOR YOU? Has the motor been on the boat that is giving you the problem all along? Did it ever work properly without revving to 5800 on the current boat it is on? Is this a new problem or has this been the issue with said boat since you had it? Has anyone modified the hull in front of the motor? Is theboat taking on water that you are unaware of causing it to be much heavier than it should? These questions may sound stupid but I am asking them for a very good reason.

As stupid as these questions sound, answer them before you change anything else. I may be able to help.

Holwachagot

[LuckyLady]

I could be wrong but his post is a little difficult to follow

Fuel related issues will cause a boat not to go over a certain rpm, and definitely will restrict top end speeds.

With multiple fuel pumps kicking in at different times, if there is a problem with the high pressure not delivering will create similar problems

Not to mention the engine runs on part of the cylinders at lower speeds, could also be a bad/clogged injector.

The computer controls the fuel flow and if its not firing on all cylinders it can lose that cylinder, and keep on kicking not skipping a beat because the engine is already running on part of its cylinders and it feels no different to the user.

Gears & clutches do wear but do not restrict speeds or slip.

Clutch wear is normally grinding in to gear or slamming in to gear with a noise.

Gears typically break and if a gear is worn he would feel the effects across the board

Every gear is constantly engaged and turning at every moment other then neutral

Maybe he can give us some further detail, what ever it is I hope he gets it worked out

[Mirage36]

Sounds like prop aeriation to me. I have no suggestions other than the odvious causes of that.

[HOLWACHAGOT]

Mary,
You are much more mechanically inclined than I am. I was not aware that with fuel issues the engine would still achieve full RPM's(5800). I would assume that you would hear sputtering or missing at some point before hitting full throttle if the issues were fuel related. Again, that would be my assumption, and it would not be the first time I made an ass out of myself if I was wrong...this is a great place for an expert to chime in..
Is it your experience that with fuel issues such as water, low fuel pump pressure, etc. that the engine will achieve full throttle without spitting, sputtering, missing, etc?
My YAMAHA 115 HP 2 Stroke runs 57-5800 RPM with the stick pinned in the corner. I would bet my favorite fishing rod that if the fuel was bad, or the fuel pumps were tired, or the filters had crapola in them, that it would never make 5800 RPM without me hearing it miss, seeing the engine shake, or something. I am asking for two reasons...To try to elicit some help for Neil and for my own future info. Any help greatly appreciated.

Is there any possibility that something is stripped out or fastened improperly on the prop shaft(for lack of a better term), i.e. something b/w parts 47-58?

I agree with you, Neil's initial post does not give enough info.

Suppose this motor is new to the boat and not far enough down in the water...

Holwachagot

[LuckyLady]

The hub sounds likely the cause but it says checked so its a little tough to understand.

The reason for my fuel related answer is because he stated that the prop and hub were okay. Also in my past experience with gear case issues knowing that they just do not slip like that fuel is the 3rd option.

Will a boat reach full RPM with a fuel problem,its possible. The more you increase throttle the demand for fuel increases, there for is slight debris are blocking, with high pressure they push thru "sometimes"

With all the bells and whistles that motors have anymore fuel seems to be the common cause. Never are they the same, little by little.

Fuel related issues can suck because there is so much to the fuel systems now a days it could be anything.

A knock sounding like its coming from the gear case can be clogged injectors. We had this happen recently where we even changed the gear case. With the engine idling in neutral engine was fine not shaking or sputtering at all. Drop it in to reverse or forward knocking badly and with throttle advance it would knock louder and stall out. Had me fooled I thought for sure it was a gear case issue, changed the case problem was gone. We did not have time to mess around with missing the 1st fish day of the tourney, swapped out the case. Dealer inspected pulled it apart no signs of any wear or problems what so ever. But problem was gone??

3 trips later starts acting up again with no knock but dropping RPMS while underway from 4300 down to 2300 back and forth, drop the throttles back to neutral rev the piss out of it in neutral, notta, run for another 15 same thing, next day gone.

Moral of the story the whole time it was fuel related, would reach full rpms and I would not put anything past fuel.

As for this question: Is there any possibility that something is stripped out or fastened improperly on the prop shaft(for lack of a better term), i.e. something b/w parts 47-58?

Typically you would hear griding of some sort, and see the case lock up. Everything is keyed and shimmed in there and if something was slightly out of wack you would know. Its by no means like a trany in a car, with fluid heating up getting thin and slipping. Gear is either there or not there or making noise of some sort

[HOLWACHAGOT]

Gotcha. Thanks for the info Mary.

If I may ask another question...WHERE THE HELL IS NEIL?

Holwachagot

[LuckyLady]

Originally Posted by HOLWACHAGOT

Gotcha. Thanks for the info Mary.

If I may ask another question...WHERE THE HELL IS NEIL?

Holwachagot

No problem.

Checking his hub again!