My 99 Speedster has one motor that has been starting to surge. As you run across the lake at speed the rpm will drop and maybe hold for a little then it comes back up. A first it would do this and run like that for a little while then clear up and run fine the rest of the day but now it keeps doing it. On a recent trip out that motor quit and would not restart so i took it home and the next morning it would start but when you tried to give it gas it would die. I pulled the fuel line and it did not have a very good flow so i put a new mikuni high flow fuel pump on (same set up as the other motor) and replaced the lines to the carb and the vacuum line and a new filter. Yesterday i took the boat out and i am still getting the surging. When i run it full throttle it may run up to 7000 rpm and as you go it will drop down in rpm to maybe 3-4000 then run a little and come back up to 7000 rpm. I did notice that if i back off to around 5000 rpm i did not get the surging as bad, this makes me think its a fuel issue but at this point im not sure and dont know what to do next. If anybody has any idea of what it may be please let me know. Thanks
Since this post i have tried numerous things and still get the same results. Tried lots of things and thought if it went from one motor to the other i would know what it was. IM not sure where to go from here but any help is greatly appreciated. Here is the list of stuff i've tried.
1. swapped carbs from motor to motor.
2. new rotary valve and sanded the cover down smooth, clearance on the valve checks good.
3. swapped water regulator from one exhaust to the other.
4. swapped where the fuel line comes out of tank.
5.Ran long pulse line from opposite motor to motor. (Thought maybe not getting a strong vacuum off the motor.)
6. Double checked the timing on the rotary valve.
7. pulled line off at carbs and made sure its getting good flow.
8. bypassed fuel filter. (seen on here where these fuel pumps can collapse the paper filters)
9. checked compression on motor. (145)
10. new fuel lines from tank to carbs and new pulse line.
Since this post i have tried numerous things and still get the same results. Tried lots of things and thought if it went from one motor to the other i would know what it was. IM not sure where to go from here but any help is greatly appreciated. Here is the list of stuff i've tried.
1. swapped carbs from motor to motor.
2. new rotary valve and sanded the cover down smooth, clearance on the valve checks good.
3. swapped water regulator from one exhaust to the other.
4. swapped where the fuel line comes out of tank.
5.Ran long pulse line from opposite motor to motor. (Thought maybe not getting a strong vacuum off the motor.)
6. Double checked the timing on the rotary valve.
7. pulled line off at carbs and made sure its getting good flow.
8. bypassed fuel filter. (seen on here where these fuel pumps can collapse the paper filters)
9. checked compression on motor. (145)
10. new fuel lines from tank to carbs and new pulse line.