115 two stroke, no power be**** 1100 -1800 rpm

[dingram]

I’m having a very difficult time getting my 89’ Yamaha 115 two stroke to run right.

I have had the carburetor professional rebuilt by a Yamaha certified tech and I have had to take the boat back two times to troubleshoot the issue. I’m getting nowhere with this particular tech and before I take to another mechanic I’d like to see if I can resolve the issue myself.

When I initially got the boat back it ran great, but at the end of the day the engine would not run at full power between 1100 and 1800 rpm. It sounded and felt like it was only running on two cylinders. As the rpms slowly increase over 1800 rpm it cleans up and runs at full power.

At idle all cylinders are firing. The issue is in the power range 1100 – 1800 rpm when trying to plane up. Powering onto the trailer is no picnic either.

I do have a fuel/water separator.

My plan is to check the bowls and the main injector ports for any trash or blockage.

Any other suggestions or possible solutions are welcome.

Dave

[boats.net]

Check the fuel filter on side of engine, if it has trash or water in it then then fuel/water filter needs to be changed. Try a new set of plugs and when out on water pump the fuel primer bulb, if engine boggs down when pumping bulb the fuel pumps need to be rebuilt or replaced.

[Norway73]

Hi,
If you can borrow a tool to check your compression on each cylinder and start with this,,if you get the same results on each cylinder you will for sure know that there is something wrong with the fuel or eletrical system !!

If you have good reading's on each cylinder take of the carb's and give them your best clean ever. Try then to get a seperate gasolin tank and connect it and go for a ride and see if this did help.....
If you should end up with strange figures on the cylinder compression test,, you could have several problems. Burned piston rings, reed-valve leak, or minor damage to the cylinders and so on !!
Anyway try out a few of this tips and post your progress - good luck !!

[Bluebird]

Carbs,Carbs,Carbs. Low speed jets are clogged, thats what happens to mine any way. Do a search on clogged carbs. You'll get the idea.

[slim]

i agree with bluebird. if it ran good at first and then bad again, then it has to be in the carbs. obviously they didnt get all the trash out of them, it has nothing to do with your fuel bulb or filters

[Deepwatertroller]

Dingman,
I had a a similar problem with my 94' 250. My problem was that it wouldn't go above 4200 rpm. I did notice that if I squeezed primer bulb that it would noticeable increase rpms. Took it to dealer. Had CDI checked, throttle position sensor adjusted, #6 carb rebuilt, water seperator added, 3 fuel pumps replaced and reed valve on # 6 cylinder replaced. After all that found out main problem was simple: fuel primer bulb. A missing tab on reed was was secondary problem for performance. Try replacing fuel primer bulb and adding new fuel line. It will cost about $25. Have heard of several people having problems with inner wall of fuel collapsing. Good luck.