motor bogs down over 3500 rpm

I have a 1987 yamaha 2 stroke saltwater series motor starts and idles nice anything under 3500 rpm is good. I try to go over 3500 rpm and it bogs down I have to go to neutral and throttle back up to 3500 rpm to maintain speed. I changed fuel pump,plugs, gas filter,new gas and still same problem.

Check to make sure you have spark on all cylinders -----------Do a compression test as well.----------------If those are good then likely the carburetors need to be cleaned.

I changed plugs I have a spark on all plugs I hooked up the fuel pump to independent gas tank . I'm going crazy just trying to figure this problem out all of my connections to the batteries are nice and tight it starts nice when I put it in neutral press the throttle it sounds great . I put back on the water just won't go over 3500 rpm the fishing season in jersey is coming to an end I need to get out there help

Your compression test results indicate what ???-------------Check that spark will jump a gap of 7/16" or more ,laying plugs on the block is not good enuff.----------------Sound like you have a dead / non working cylinder.--------------Reed valves been checked ???

right now its out of my hands I took it to the mechanic what those numbers were I really don't know he did a compression test and said that it was okay

it works great last year all the way to the very end I had the boat winterize I've been having this problem since early spring but now it just keeps getting worse

Frank,
Check the fuel pump. If you do a search most of the people have problems with high RPMs it usually the fuel pump. Good luck

I am having the same problem with my 2005 Yamaha 115 4 stroke. it has only 90 hours on it and always maintained properly. I was down in the Keys and had the same problem. It would plane out and get up to 3500 RPM and then slowing bog down. If I fether the throttle I can keep it on a plane but seems like it is starving for fuel. When I got home I brought it to my mechanic who assumed I had watter in my gas and my injectors may be clogged. He has checked everything and we are at a stand still. He called Yamaha and said they are not aware of a problems but I have heard others experiencing the same thing. One suggestion I heard was to install a high pressure fuel pump. The jury is still out on this and my mechanic who is in the business for over 30 years is determined to fugure it out. I will let you know what happens and you do the same.

Thanks for your replies my mechanic is also determined to resolve this problem .he also changed the fuel pump but we are still having the same problem. What doesn't make sense to me how it worked geat to the very end of the season.I got it winterized, it sat for 6 months and all of a sudden I'm having this problem.we ruled out bad fuel by hooking up to an independent fuel tank.mechanic said he doesn't think it's a bad carburetor because there are ways of checking it and it seems fine ill keep you posted

Well here we are October 19,2011 I have till the end of november to fish I checked in with my mechanic to day and they are in the process of removing the carburetor to see what's going on in the inside. He changed the fuel pump some would say he should have put in a high pressure fuel pump the mechanic said my motor is carburetor not fuel injected. I try not to know more than the manufacture. If that's the pump for that model that what should be in. He also ohm out the stater and it checks out ok ill keep you posted.

Well here we are my boat was finally fixed after changing 2 fuel pumps some sensor located at the fly wheel,spark plugs,gas filter it turned out to be a pinched fuel line at the motor clamp. That explains a lot my boat was winterize and it sat for 6 months with the motor in the tilted up position pinching off that fuel line something so simple can make you belive that the problem is elsewhere. With the parts and labor it came out to $650.00 dollars ouch . I know my mechanic really tried he said to ease the pain he would winterize the boat for free that's about $350.00 savings so I guess its not that bad. I would like to thank everybody for there response.good luck everybody time to go fishing.

In the future get a portable fuel tank with a separate primer pump and hook it up directly to the motor.what my mechanic did he hooked up the primer hose line that came from my motor to the portable fuel tank that didn't rule out the entire fuel line . If this helps anyone experiencing the same problem please write back I would like to know.