1985 25 hp Johnson, no top end power!!

[jschuh]

I have a 1985 25 hp johnson (J25RLCOS). I've put in a new head gasket, water cover gasket, thermostat, impeller, and two new ignition coils. the thing starts in one or two pulls and will stay running til i shut it off. i put on new fuel lines, connectors and changed tank. i can turn throttle wide open when motor is in neutral and it goes fine, same for reverse. as soon as it put the motor in forward, i can only open up about 5/8 throttle and engine sounds like it's bogging out out or flooding. i have a repair manual and think i've nailed it down to either the power pack or the stator.
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i'm checking to see if anyone else has had similar problems and what the diagnosis was, thanks for your time.

 

[Daviet]

Re: 1985 25 hp Johnson, no top end power!!

Use an inductive timing light to check spark when the problem is happening. If you have steady spark on both cylinders your ign system is OK.

Try squeezing the primer bulb and see if the engine picks up, if so check your fuel pump operation.

Try squirting some fuel mixture into the carb, if engine picks up, it is time to overhaul the carb, paying attention to the high speed jet and all passages.

 

[jschuh]

Re: 1985 25 hp Johnson, no top end power!!

I put in a new fuel pump kit and seems like it's getting fuel to carb. i will try a mixture of fuel/oil and spray into carb. thanks for the advice.

will a bad power pack cause loss of top end?

 

[bktheking]

Re: 1985 25 hp Johnson, no top end power!!

A bad powerpack usually results in no spark.

 

[jschuh]

Re: 1985 25 hp Johnson, no top end power!!

Will a carb rebuild kit be enough if it is a carb problem to fix it? or any additional operations needed to work properly?

 

[kbait]

Re: 1985 25 hp Johnson, no top end power!!

I carb-kitted virtually the same motor last year and afterward it had the same exact problem. I then set the float so it bent slightly toward the carb body when inverted (supposed to set parallel, which it was), and it then ran perfect. I don't know why, but obviously it needed more fuel in the bowl.