2003 yamaha 115 4-stroke

[bzkt42]

HELP!! My '03 yamaha 115 4-stroke bogs down. I can rev up just fine. But, once I engage the prop, I can only get up to about 1500-2000 RPM. Had it in the water and could only go about 8 mph at full throttle. The motor runs really rough passed the RPM stated above. I've treated the fuel and changed the fuel filter. I dont think it's a fuel issue. Because as stated above, it only acts up once I engage the prop. Can someone help?

 

[99yam40]

Re: 2003 yamaha 115 4-stroke

Sounds like fuel issues to me, if you run cylinders lean it can and will hurt the pistons and cylinders themselves .
Do a compression test or leak down test to make sure to motor is still mechanically sound and then check spark on all cylinders.
Check to make sure the timing is moving properly and is in spec

make sure the alarm system is funtioning properly and the motor is not going into safe mode

If all this is normal then you have a fuel problem

 

[SparkieBoat]

Re: 2003 yamaha 115 4-stroke

99 what is the proper procedure for a leak down test??

 

[99yam40]

Re: 2003 yamaha 115 4-stroke

Never done it myself, do not even own the tester as I have never owned a 4 stroke outboard.
But from what I have read it is they proper way to test them and is simple as long as you have regulated compressed air handy and the tester. Just put cylinder on top of compression stroke and hook the tester up and read the leakage. If it is not sealing properly , you just listen to see where it is coming out of (intake,exhaust, or crank case )to determine what the problem is.

 

[SparkieBoat]

Re: 2003 yamaha 115 4-stroke

thanks..I was not sure how to do it...I hope I can get my 4 stroke fixed soon and get RID of it and never have to worry about it again.