1985 Johnson 25hp stalling out at low speed

[jmeny]

I bought an '85 johnson 25hp (J25ELCO) a little while back as an upgrade for a boat of mine, and the guy I got it from said that last year the gear oil was changed, carbs were rebuilt, and it passed its compression test with flying colors. Took it out for a test run today and had a few questions...

First off, when starting it up (at any point after turning it off), it revved real high in neutral-thinking I need to adjust the idling speed screw?

Second, it ran fine at high speeds but then it started bogging up and running fast in little spurts - noticed the ball for the fuel line wasn't getting pressure, and as long as my buddy was pumping the ball, it ran well at all speeds except if it was going slow (it would sputter and eventually stall). It's important for me to be able to go slow for trotlining and trolling without it stalling out, so I need to figure out what's wrong. I'm gonna start off by getting a new fuel line attachment to the gas can to see if that makes a difference (which I'm pretty sure it will for fast speeds), but I was wondering if there was something else I should look into. I thought this might have something to do with the low speed problem too, but I'm not sure. I'm not familiar with working on engines, but hoping to learn a little and figure this out.

Any help is much appreciated-Thanks

 

[tx1961whaler]

Re: 1985 Johnson 25hp stalling out at low speed

Make sure the gas tank is vented well. Check for leaks in the fuel lines, both for air and fuel leaks. Normally if pumping the primer ball corrects the problem it indicates a bad fuel pump.

 

[jmeny]

Re: 1985 Johnson 25hp stalling out at low speed

Thanks, I'll look into that - pumping the ball at low speeds didn't seem to help though - idling with the fast idle lever locked in the start position or going slow just seemed impossible - would these problems be related to the fuel pump too or am I looking at another issue?

 

[dew2]

Re: 1985 Johnson 25hp stalling out at low speed

That not running slow could be the lowspeed air fuel mix needle try opening it counterclock wise 1/4 turn,see if that improves the as you said>>First off, when starting it up (at any point after turning it off), it revved real high in neutral-thinking I need to adjust the idling speed screw?

 

[jmeny]

Re: 1985 Johnson 25hp stalling out at low speed

Ok thanks just found that in the manual, I'll give that a shot next time I go out and see if it makes a difference.

 

[Cofe]

Re: 1985 Johnson 25hp stalling out at low speed

Test the fuel pump. If you have to pump the bulb at high speeds to even out the motor, this indicates a fuel problem.
With a old fuel pump diaphragm, they gets streched and won't pump correctly.

 

[jmeny]

Re: 1985 Johnson 25hp stalling out at low speed

Replaced the line from the gas can to the motor with new clips and adjusted the low speed air/fuel mix needle - works well now at all speeds, just has a bit of a problem idling still (too slow when the lever is in the 'run' position). While I was lookin at it I noticed the plastic idle speed screw is stripped and just pops back out when I try to put it at a certain setting - does anybody know where I could find a replacement screw for this engine? I looked around but can't seem to find what I'm lookin for. Thanks

 

[kbait]

Re: 1985 Johnson 25hp stalling out at low speed

go here: http://epc.brp.com/SiteMods/BRP_Public/BRP_Public_Login.aspx?ReturnUrl=/Index.aspx

navigate to your motor, and choose the part group you need. Find the part number you need and call your local marina.