Ignition stuttering over half throttle

Challenger v8

Recruit
Joined
Jun 9, 2015
Messages
5
1998 40hp Johnson ignition stuttering at full throttle any advise welcomed.2 cylinder engine ,have tried to check a few things like the over heat switch unplugged the tan wire , kill switch wire black/yellow and also unhook vro connector, to no change. The vro has been bypassed now mix fuel .any help will be greatly welcomed.
 
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SparkieBoat

Captain
Joined
Aug 17, 2009
Messages
3,643
water in your fuel, bad fuel pump, low compression, bad plug, bad plug wire, clogged carb, bad fuel line connection. ect.
compression and spark check, then test fuel pump.. it is a process of elimination. you have not eliminated much yet.
 

jakedaawg

Rear Admiral
Joined
Jun 26, 2012
Messages
4,275
Yep...compression test, open air gap spark check and fuel sample first. Report back. The rest will come from these answers.
 

Challenger v8

Recruit
Joined
Jun 9, 2015
Messages
5
Sparkie boat captain Actually did a carb soak ,new kits in both carbs new gas lines new tank,compression is equil on both cylinders /105 psi ,motor not a lot of hours on engine .
 

Challenger v8

Recruit
Joined
Jun 9, 2015
Messages
5
Jakedaawg Made me a spark checker out of plastic , have good 1/2 blue spark while spinning with out plugs in ,just don't know why I'm loosen it on one cylinder over half throttle . Almost like stutter box on hot rod.
 

Challenger v8

Recruit
Joined
Jun 9, 2015
Messages
5
Thanks for all input on my motor found that it was the power pack -cd box causing problem ,thank again for input!
 
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