newguy0042
New member
hi everyone. I am new to all this. I have a 99 Yamaha c115 TLR 2 stroke that keeps stalling and just not running right. Things I have done already: cleaned carbs, replaced fuel lines from tank to motor, replaced fuel pump, checked reeds, changed plugs, checked compression (140) on all 4 cylinders, added fuel/water separator, changed fuel filter, checked for air leaks, and attempted to adjust air mixture.
symptoms I am having: ran good for a while. Then it began to foul plugs. I would cruise at WOT speed around 40 mph. After running for about 20 minutes at WOT, i would lose top end like it was starving for fuel. I could back off to around 30 mph, and it would run fine. As I get back to WOT, it would run good for about 2 minutes, then lose the power again. The plugs were black with carbon foul. Asking around, i was told two different things about the air mix screw settings. One was two turns out for general start point, and the other was only 5/8 out from seated. I tried both. During adjustment, not much changed on the idle side of things. I ran the boat for a while in the water moving place to place and adjusting each time i stopped. Got it running good at WOT with RPM in range, but then starting having stalling at idle. Last thing i changed was fuel pump. Now it will run for a few minutes and then stall like its not getting fuel moving to the motor. Had a thought of putting an electric fuel pump to see if this changes anything. Seems to be an adjustment issue somewhere. what is the actual start point on the air mix screw? Or would this just be easier and better to pay several hundred dollars to put in the shop? Any help would be great. I'm just frustrated at this point and trying to save a little money where I can. First boat owned and its not going well. I'm starting to feel the analogy of B.O.A.T., break out another thousand....
symptoms I am having: ran good for a while. Then it began to foul plugs. I would cruise at WOT speed around 40 mph. After running for about 20 minutes at WOT, i would lose top end like it was starving for fuel. I could back off to around 30 mph, and it would run fine. As I get back to WOT, it would run good for about 2 minutes, then lose the power again. The plugs were black with carbon foul. Asking around, i was told two different things about the air mix screw settings. One was two turns out for general start point, and the other was only 5/8 out from seated. I tried both. During adjustment, not much changed on the idle side of things. I ran the boat for a while in the water moving place to place and adjusting each time i stopped. Got it running good at WOT with RPM in range, but then starting having stalling at idle. Last thing i changed was fuel pump. Now it will run for a few minutes and then stall like its not getting fuel moving to the motor. Had a thought of putting an electric fuel pump to see if this changes anything. Seems to be an adjustment issue somewhere. what is the actual start point on the air mix screw? Or would this just be easier and better to pay several hundred dollars to put in the shop? Any help would be great. I'm just frustrated at this point and trying to save a little money where I can. First boat owned and its not going well. I'm starting to feel the analogy of B.O.A.T., break out another thousand....