Optimax won't open up.

[NorenKooper]

I have a 2008 Optimax 150 that will not consistently open up beyond 4000 rpm. Occasionally, I can run the 9.9 kicker motor, then the big motor will run at 6000 rpm. The next time I put the boat on the water, the problems start all over again.

I took it into the shop and got new spark plugs and a new fuel separator. I had a diagnostics ran on the motor and it came back perfect with only 54 hours on it.

I was told instead of teeing the kicker motor fuel line directly into the big motor fuel line, I needed to put a brass tee in with valves so that I could shut off the fuel line that wasn't being used. I was told the big motor was pulling air back through the kicker motor fuel line.

​​​​​I did that and that didn't work. It still takes me running the kicker motor first to get the big motor to run at 6000 rpm. The next thing I did was replace the primer ball on the fuel line to the big motor because it would not get hard. That still didn't do the trick. Now, I've been told to check the low pressure fuel pump. Can anyone give me any advice on this? Thanks.

 

[NorenKooper]

I just spoke with a boat mechanic about this issue. He said that if it was in his shop, the first thing he would check is the low pressure fuel pump. After that, he would check the coil and then a dropped cylinder.

I've been researching forums all morning concerning these other culprits he mentioned and they all make sense. When pushing this boat WOT, it can all of a sudden jump up or drop down 1000 rpm for no apparent reason. What is interesting is that it drops/jumps consistently the same amount of rpm's

This makes it sounds like it is something electrical now and that the running of the kicker is coincidental because running the kicker doesn't always fix the problem.