JOHNSON 25hp only runs to 1/4 throttle

[Wantoboat]

Just purchased a 1988 Johnson 25 hp and rebuilt the carb. New gas tank and OMC brand fuel line.<br />Started first pull! Idled ok but when I gave it gas to get on plane, it only ran at high speed for about 15 seconds max. After, I could only run it to about 1/4 throttle. After that it would sound as if it was getting no fuel. I could make it speed up briefly (about 2 seconds) by pumping the primer while holding the throttle to full.<br />After idling for a short time, I could do the same thing. Any ideas?

 

[Don Ermis]

Re: JOHNSON 25hp only runs to 1/4 throttle

Wantoboat,<br />Might want to check the title "Evinrude 88SPL no power". At present I am working on my 1988 Evinrude 88SPL outboard that is having problems similar to what you describe.

 

[shooter26]

Re: JOHNSON 25hp only runs to 1/4 throttle

I had also had a similar problem on my 75 25hp Johnson. First I replaced the fuel tank, hose, bulb and fuel pump. I would still bogg .Rebuilt the carb.(no change) Then I noticed I had a cracked coil (leaking spark) replaced it. Problem did not go away <br />Then I saw water coming out between the spark plug threads on the top cylinder (replaced head gasket)Changed boot and wire on new coil becuase they are crap and it still leaked spark around it. Adjusted the low speed Idle (lean/rich)screw to the best position. Took it out to the lake...WOT 10 minutes no problems Not exactly sure what the problem was but it's fixed now Hope this helps you in some way.

 

[Beernutz]

Re: JOHNSON 25hp only runs to 1/4 throttle

Are you certain that you got the mainjet orifice completely cleaned out when you rebuilt the carb? If it's brass, gasoline sediment can be very close to the same color.