1987 Johnson 140 HP stalls on idle when hot

[mhberman]

I have a 1987 Johnson 140 HP outboard that stalls on idle when the engine is hot.<br />It starts fine when cold and runs great with a sweet spot around 4400 rpm. However after running for a while it dies if you idle (800 rpm) and is very difficult to restart. Mostly I end up getting towed back to the slip and have to wait until the next morning to start it again. Even on a short run from the slip to the fuel dock (10 min) it will fail to start after fueling up. The engine floods while trying to restart.<br />We have already changed the stator and just had the carb rebuilt thinking it was a stuck float.<br />Any ideas? Thermostat perhaps? Electric ignition?

 

[OBJ]

Re: 1987 Johnson 140 HP stalls on idle when hot

Welcome to iboats Rutgers!<br /><br />Take a look up under the flywheel and see if there is any goo dripping around. If so, stator probably shot and took the charge coil with it.<br /><br />If she looks OK, do the old hair dryer test. Start the engine on muffs and before she gets warm, take the wifes (or girl friends) hair dryer and start heating the ignition components up a little. Start with the power pack. If she dies after a little heat is applied to any of the ignition components, you probably found the problem.

 

[Jcrain]

Re: 1987 Johnson 140 HP stalls on idle when hot

OBJ: If it was a powerpack, coil, etc, wouldn't it die while at higher rpms, too? I have a 90 40hp jonnie that does ALMOST the same as what Rutgers is doing, except mine will start but I have to get it off idle pretty quick or it will die. It will idle all day as long as I never go out cruising. After running 50% throttle up to WOT for 10 min or so, it'll die when I come back to idle

 

[OBJ]

Re: 1987 Johnson 140 HP stalls on idle when hot

Hi ya' Jcrain. Heat does some strange things to electronics. What you see in one situation may not apply to the next. I know the rudiments of electronics and have a basic knowledge of how packs and coils work...to give you a fact based "good" answer...well, I'd probably confuse you and myself more by faking a good answer than giving an understandable answer. What I know for sure is that the "hairdryer test" can work.<br /><br />Your particular situation has a more fuel flow related ring to it, maybe a sync & link problem or a readjustment of the low speed needles. Carbs been overhauled lately?

 

[Jcrain]

Re: 1987 Johnson 140 HP stalls on idle when hot

Not sure of this jonnie. I got it a couple of months ago attached to a pontoon boat. I haven't done much to it, been tinkering with a 50 evinrude to replace it with. <br />I got a manual for the evinrude (Clymer) but it doesn't cover the johnson. They LOOK the same but will wait till I get the proper book before I mess with it too much. It is usable right now, just a bit frustfrating at times

 

[mhberman]

Re: 1987 Johnson 140 HP stalls on idle when hot

What are low speed needles? Jcrains problems dont seem very different from mine.<br />Jcrain, after your engine dies on idle, how long before you can start it again? Do you flood the engine trying?

 

[Jcrain]

Re: 1987 Johnson 140 HP stalls on idle when hot

The engine will USUALLY start right back up, but I need to get it in gear and shoot a bit of gas to it or it will die again. If I let it sit for about an hour or so, it'll start up and idle for hours again. To me, it seems heat related. I haven't tried running with the cowling off yet but I'll try that sometimes this week.

 

[Jcrain]

Re: 1987 Johnson 140 HP stalls on idle when hot

Hmmmm cowling OFF didn't do anything. Just might be fuel and not ignition