200hp acceleration stumble

[balliztic bucket]

I have a 1998 johnson 200hp with six carbs. when I slowly accelerate it stumbles very badly but if I floor it and accelerate quickly it does just fine. It acts just the opposite of a clogged fuel filter (wich is; accel. slow ok, but accel. fast stumble.) why does my motor do this? I dont like having to floor the gas just to get off the boat launch. it makes it very difficult when I'm docking or loading back on the trailer. What can I do to fix this? Please help.

 

[tashasdaddy]

Re: 200hp acceleration stumble

linc n sinc, or dirty carb. make sure you are getting spark on all cylinders, with it idling. pull one plug wire at a time, listen for the rpm change. replace wire , a go to the next. if no change it is either spark or lack of fuel.

 

[balliztic bucket]

Re: 200hp acceleration stumble

wouldnt a lack of fuel make it so when I floor it it would stumble instead of when I accelerate slowly and it stumbling?

 

[Dhadley]

Re: 200hp acceleration stumble

Just so you know, if you have a 1998 200 you don't have 6 carbs. You have 4. Two 2 barrel carb assemblies and two single barrel carb assemblies. Yes, 6 throats or venturis but 4 carb assemblies.

Anyway, lets start at the begining. How's the compression? What spark plugs are you using? Are the carbs clean or has the motor been sitting for a while (winter storage)? Did it just start doing this?

 

[LubeDude]

Re: 200hp acceleration stumble

It very easily could be your plugs, Old, dirty or wrong ones!