I am having issues with my carbed 2004 Yamaha 150 TXRC 2 stroke motor and I am at my wit’s end. I have rebuilt/replaced everything that I can, and am still having the same issues. I will try to keep this short.
The motor cranks and idles, but isn’t what I would call a smooth idle and you can smell raw gas when idling. When you give it throttle to get on plane, it is missing on some cylinders, but then will hit and smooth out and run ok up to around 32-3500 rpm. Once you give the motor full throttle, it will speed up and then will start to bog down until you pull back on the throttle.
Here are the troubleshooting steps and repairs that I have made.
Interestingly, while the motor is running in neutral, you can pull the plug wires off of the 3 cylinders on the left side of the motor and there is no change in rpm, but you can see/hear the spark. Also when you pull the plugs out on that side all 3 smell of raw gas and are clean. video of this can be found here:
https://photos.app.goo.gl/AVaFDlcvwjuON0M23
I am hoping that someone can chime in that has some knowledge of this motor and can help me before I give up. I have had this boat for 5 years and never had an issue till now. It’s a pretty low hour motor, not sure how many exactly, but I don’t abuse it and have always kept it maintained.
Thanks in advance.
The motor cranks and idles, but isn’t what I would call a smooth idle and you can smell raw gas when idling. When you give it throttle to get on plane, it is missing on some cylinders, but then will hit and smooth out and run ok up to around 32-3500 rpm. Once you give the motor full throttle, it will speed up and then will start to bog down until you pull back on the throttle.
Here are the troubleshooting steps and repairs that I have made.
- All 6 cylinders have great compression. 127 +/- 2 psi on all cylinders.
- I have rebuilt the carbs with new jets, needles, and gaskets. Readjusted the float bowls. Even made sure to pull welch plugs out to clean and adjust air bleed screws.
- Replaced all fuel lines above and below deck with new 3/8’s marine grade line
- New primer bulb
- New fuel pumps on side of engine
- All new check valves in the intake and crankcase because over half weren’t functioning
- New spark plugs gapped correctly.
- Has fresh gas in it
- Visually inspected the reed valves, and all look good.
- Have good strong spark on all cylinders.
Interestingly, while the motor is running in neutral, you can pull the plug wires off of the 3 cylinders on the left side of the motor and there is no change in rpm, but you can see/hear the spark. Also when you pull the plugs out on that side all 3 smell of raw gas and are clean. video of this can be found here:
https://photos.app.goo.gl/AVaFDlcvwjuON0M23
I am hoping that someone can chime in that has some knowledge of this motor and can help me before I give up. I have had this boat for 5 years and never had an issue till now. It’s a pretty low hour motor, not sure how many exactly, but I don’t abuse it and have always kept it maintained.
Thanks in advance.