1985 25hp tiller J25RLCOS, restarting when warm issue

[SweetD]

Hi Folks,

I'm running into a problem this season with the "kid's boat" 25 Johnson mentioned in the thread title. Last season no issues.

Starts fine when cold. Runs perfectly at all speeds.

If I go to start it again while it is still "warm", it is very difficult to start. Seems like it floods easily.

If I wait 10-15 minutes or so after trying to restart when warm, it will usually start up again. (again, seems flooded)

I rebuilt the carb last year and examined it again earlier this season - it had slightly come off of the gasket to the motor so I re-attached it and used a bit of Lock-Tite on the studs - it's holding fine now.

This motor has the manual primer system (plunger). Last time I was messing with trying to start the motor, I pulled the plunger a couple of times (again, when "warm"), and all of a sudden the motor fired right up and ran perfectly. I feel like the plunger may have something to do with it.

I am setting the throttle at the "Start" position each time by the way.

Also, I am running the spark plugs from last year (new last year), and have not yet installed new plugs this year. My fuel is always fresh and conditioned with marine Sta-Bil and Sea Foam.

What else can I tell you to help diagnose?

What should I be looking for with the "doesn't want to start when warm" condition?

Thanks very much,

Dave

 

[oldboat1]

Don't use the primer when warm, and make sure the red lever is in the run position (parallel to the solenoid body). If the fuel is always fresh, you do not need any additives. Ratio is 50:1.

 

[SweetD]

Don't use the primer when warm, and make sure the red lever is in the run position (parallel to the solenoid body). If the fuel is always fresh, you do not need any additives. Ratio is 50:1.

Thanks oldbboat1...I'm pretty sure this motor does not have a red lever/solenoid since it is a pull start - is that correct? My bigger motor has it.

Thanks.

Dave

 

[SweetD]

I should also mention that last time this happened, I had a second hand advance the throttle a bit more past the start position and the motor kicked over. Could this be indicative of a carb idle adjustment needed?

Note: I don't want to sound like a newbie here...I'm mechanically inclined and do a lot of my own work, I'm just not real familiar with this motor yet.

Thanks,
Dave

 

[oldboat1]

apologies SweetD. You did say it had a manual primer.

I believe that motor has a low speed mix adjustment needle (top of the carb). If so, have you tried adjusting that? It may be set a little too rich for starting when hot (though this seems contrary to your point about using the plunger to start when warm). As a starting point, that needle would be set 1 1/2 turns open (counter clockwise) from lightly closed. It is then adjusted for best running when the engine is warmed up -- typically slightly more lean. It's possible that the needle needs to be adjusted slightly richer for cold starting, then returned to the "running" position. (Changes are in 1/8 turn increments.) There is also a throttle idle setting, although I'm not sure where it is on that particular motor -- bumping that to a slightly higher rpm might also help.

 

[SweetD]

oldboat, thanks for the guidance, that all makes sense. I will consult my service manual for the carb settings as well. It has to be something pretty simple...like I said, I did rebuild the carb, but I have not touched the settings on it since then, and last season (after the carb rebuild) the motor started easily no matter what temperature condition. This season it's more difficult, always something with these things!

Dave

 

[boobie]

What's the compression on it and how big of an open air gap will the spark jump when cranking ??

 

[SweetD]

What's the compression on it and how big of an open air gap will the spark jump when cranking ??

I have not done a compression or spark gap check on the motor this season, so good question. I do have the equipment to do so. I will say that it runs like a raped ape after it starts!

 

[flyingscott]

Turn the throttle as far as it will go in neutral to start it. The start position is only a suggestion.

 

[SweetD]

Thanks guys, I will report back with any progress. Son took boat out today and he said it "flooded" once out of three times he started it. He's 15 so I'm not exactly getting a detailed report...!

 

[SweetD]

Thought I would follow up on this because I always find it valuable when someone reports their eventual fix.

I found that the lower cylinder plug was somewhat fouled upon inspection. I looked at my service manual and one of the possible causes was a pinhole in the fuel pump diaphragm that would allow excessive fuel into the cylinder, and hard starting was also a symptom. I rebuilt the fuel pump and the problem seems to have gone away. An easy $15 fix. Hope this helps someone out in the future.

Dave