1999 200HP Johnson: Sputtering? at high RPM's

[onofsky]

MY '99 200 HP Johnson is sputtering at higher RPM's. I don't think it's a cylinder misfire, as it seems like it's happening to the entire engine at once; it cuts out very briefly then back on. Just started and stops doing it at lower RPM's when I back off the throttle. Smells vaguely like the problem I had with my '87 120 that needed a new "power pack".

Any ideas or experiences would be much appreciated.
Thanks,
Bill

 

[HighTrim]

Re: 1999 200HP Johnson: Sputtering? at high RPM's

Welcome to iboats. Have you tried having someone spray pre mixed fuel into the carbs when it is acting up, or pumping the primer bulb? These tests could rule things out. When were the carbs last rebuilt? What plugs are you running? Remove them and note their condition. After this you may need to check for leaks into the fuel lines, or ensure you arent trying to suck air out of a vaccuum.

 

[CharlieB]

Re: 1999 200HP Johnson: Sputtering? at high RPM's

Check the proximity of the temp sensor wires to the plug wires, EMF can cause high RPM problems.

Check the correct Champions plugs are installed, NGK's work on most but not ALL J/E's and can cause this problem also.

Lastlly, suspect the box, reasoning, it is the most expensive and their is NO RETURN on electrical parts. Eliminate all other possibilities first.

 

[onofsky]

Re: 1999 200HP Johnson: Sputtering? at high RPM's

Charlie B and High Trim:
Thanks much for your responses. As far as I know, the carbs have never been rebuilt. If it's any help, she was running extremely well days before this occurred, problem came on rather suddenly.

I'll start trouble shooting this weekend and post my findings. I appreciate you taking the time to give me some starting points.
Bill

 

[onofsky]

Re: 1999 200HP Johnson: Sputtering? at high RPM's

Oh, and Charlie B, I did not try pumping pre-mixed fuel into the carbs when she was acting up. I'll have a look at some of your suggestions first in the yard and if I don't come up with anything, I'll try attaching to a premixed tank and give her a run.
Bill