25HP Johnson 'missing' at Full Throttle

S

SylvanJohnson

Recruit
Joined
May 17, 2011
Messages
1
Gang... need some help...I'm a new boat owner...I bought a used Sylvan with a 1996 25HP Johnson and it 'misses' as full throttle...runs great otherwise. The gas is new, premium, non-oxy, with 6 ozs of Sea Foam added to the 6 gals of fuel...I wanted to make sure I wasn't at the dock 'looking' like a newbie w/bad gas (sorry to those who have)...anyway, I don't know why it's 'missing' at full throttle...any suggestions?
 
M

Midnight Krawler

Seaman Apprentice
Joined
Sep 30, 2008
Messages
37
Re: 25HP Johnson 'missing' at Full Throttle

A common cause for a full power high speed miss is a warn shift dog in the lower unit. It's basically jumping out of gear while under load. Check the lower unit gear oil for water and metal particles.

Another cause could be a bad coil. It would usually have an intermittent miss in the upper rpm range, not just full power.

One last thing, try changing the spark plugs. You never know!
 
M

Monte1961

Lieutenant Junior Grade
Joined
May 8, 2011
Messages
1,180
Re: 25HP Johnson 'missing' at Full Throttle

Midnight Krawler said:
A common cause for a full power high speed miss is a warn shift dog in the lower unit. It's basically jumping out of gear while under load. Check the lower unit gear oil for water and metal particles.

Another cause could be a bad coil. It would usually have an intermittent miss in the upper rpm range, not just full power.

One last thing, try changing the spark plugs. You never know!
Click to expand...

Not to sure if I can comprehend missing @ high rpm being the L/U, but I think I would look more towards fuel or electrical issues. ie: carb, fuel pump, sparkplugs, wires, coils, ect.ect.ect. Please post back and let us know!
 
You must log in or register to reply here.
Top