1999 15hp Johnson Stuttering at low RPM

[bonnetbum]

Hi guys

I have a 1999 15hp Johnson 2stk and it appears to stutter at low speed almost like its not firing right. Move past the low speed and it goes away. I have changed the plugs, no difference (They looked ok when i removed the old ones also...)
I haven’t done a compression test because I don’t have the equipment to.. Because I know that a question someone will ask

Is there anything I should be looking for? I am planning on putting a carb kit in to see if that makes any difference. Other than the stuttering at low speed she runs beautifully.

Any help will be much appreciated

 

[bonnetbum]

Re: 1999 15hp Johnson Stuttering at low RPM

Oh and I forgot to mention that it only happens when the motor is in water under load. Doesnt do it when im flushing her out on the shore.

Cheers

 

[bonnetbum]

Re: 1999 15hp Johnson Stuttering at low RPM

Oh and I forgot to mention that it only happens when the motor is in water under load. Doesnt do it when im flushing her out on the shore.

Cheers

Bump, I still own this boat and am having this same issue. Feels like maybe its an out of balance prop? Idle no load is fine. Anyones suggestions would be much appreciated

 

[racerone]

Compression test first.---A must do.-----Hope you have installed a new impeller as a precaution !

 

[daleyeah]

Save yourself the trouble and don't get a tester from Harbor Freight. I had look with one from Auotzone.

 

[bonnetbum]

Compression test first.---A must do.-----Hope you have installed a new impeller as a precaution !

Sure did, the water stream is nice and strong.
What kind of compression numbers should I be expecting? OR how much variance is to much?

 

[bonnetbum]

Sure did, the water stream is nice and strong.
What kind of compression numbers should I be expecting? OR how much variance is to much?

Update, got a new prop and she's running great! Must have been a slightly bent hub.

Running beautiful now. Big shout-out to ozpropellers.com.au for their great customer service and support