Johnson/Suzuki DF 140 Rough High Speed Idle?

Copro

Cadet
Joined
Jul 15, 2005
Messages
6
I don't have a dealer anywhere near me and need a little help. In neutral my 05 Johnson DF140 4 stroke idles fine at low speed, but when I lift the warm up lever it begins to surge badly at about 3000 RPM? It does seem to run fine in gear all the way up to WOT? Any advice would be helpful. I have recently replaced plugs, low pressure filter, and water seperator.

Thanks Jody
 

cousinabe

Senior Chief Petty Officer
Joined
Nov 13, 2001
Messages
765
Re: Johnson/Suzuki DF 140 Rough High Speed Idle?

i believe that motor has a rev limiter for neutral operation and is operating properly.

why would you ever rev a fuel injected motor in neutral with no load? not a good idea.
 

Copro

Cadet
Joined
Jul 15, 2005
Messages
6
Re: Johnson/Suzuki DF 140 Rough High Speed Idle?

Thanks,

I knew about the rev limiter. When it is engaged does it typically cause surging? I have never noticed this before. Just wanting to make sure nothing is wrong.

Jody
 

Rancherlee

Chief Petty Officer
Joined
Jun 6, 2006
Messages
621
Re: Johnson/Suzuki DF 140 Rough High Speed Idle?

Yes, it has what they call a Hard limiter, it cuts the spark to all 4 cylinders for a bit to get the rpms below 3000rpm hence the "surging". A soft limiter randomly cuts individual cyclinders to make it seem "smooth" while limiting the rpms.
 
Top