Idle is great ! But studders when giving it gas

[Nate1979or]

Not sure whats going on. New plugs,wires,carb rebuilt. She idles great now but cant figure out what is causing this. Air in lines?? Fuel pump need rebuilt?? I just got this boat from my father who just passed away, last week its been sitting the last 5 years. Please help me. Watch the video i posted of the problem

 

[racerone]

I am not there to look at the motor , do any testing.-----You need to report if spark will jump a gap of 3/8" or more.-----The throttle rod going to the back of the motor, is there a gap of 3/16" or so at idle on the adjustable stop found there.-----Or post a close-up video of that stop at idle position.

 

[oldboat1]

Sounds to me like a significant ignition miss, but just a guess. Have you tried priming the motor with the bulb when it begins to act up? (try to rule out fuel pump issue).

 

[Nate1979or]

Think its going into slow mode.. seems like it dont want to go over a certain rpm, spark is strong and jumps a 3/8 gap, gaps are correct on plugs,new ignition coils,rebuilt carb,new impeller, i have not checked the throttle rod.

bulb is firm.i have not yet rebuilt the fuel pump.

 

[oldboat1]

Longevity of under-the-flywheel power packs can be an issue. Might try to do some analysis: http://www.cdielectronics.com/wp-content/uploads/2013/02/CDI Troubleshooting Guide - 2012.pdf

check the throttle control rod, as indicated above.

 

[flyingscott]

Slow mode happens at 2500 rpm. The only thing that could cause that on that motor is an overheat condition.did you replace the waterpump?

 

[jimmbo]

Pull the cowl off. Check the wires going to the armature plate for skinned insulation, shorts, as you advance the throttle

 

[Vic.S]

Could it be the clutch dog slipping ?

 

[jimmbo]

That doesn't sound like any slipping clutch dog I've ever heard. Though I guess it is possible if there were almost no cogs/teeth left on the dog.

Sounds like one cylinder is missing intermittently, or perhaps there is cross firing going on

 

[oldboat1]

blue stripe wire to top cylinder, orange to bottom. Might check grounds, also disconnect the kill switch before test running, Kill switch has one wire going to the CD unit via a single amphenol connector, second wire to a coil mounting bolt.