15hp Johnson stalling

[badrano]

When I start up the motor, I have to maintain at least 1/2 choke to keep it running until is warms up. Once it warms up, it will still sometimes die out after fully opening the choke and I either have to add throttle to go to a fast idle or go back to 1/2 choke.
When I also put in in gear and ease the throttle up, it will die. All of this is with the boat out of the water using ear muffs.

Is this a fuel issue or a carb issue?

Last season, the engine died due to overheating. The cause of the overheat was due to me not realizing the motor was not locked in the full down position and rather sitting at the shallow setting and I was trying to plane out. Could this have caused any damage? The engine was serviced with a new fuel pump and carb rebuild prior to the season starting.

 

[racerone]

Try opening slow speed mixture needle 1/2 turn.----Post results of a compression test.-----No amount of carburetor work will tune a motor that is damaged.---- Model # of your motor ??----

 

[Joe Reeves]

If you state what year that 15hp is, I've overlooked it.

If the engine overheated bad.... that would loosen the cylinder head bolts... and just about every other bolt, nut, screw on the powerhead. If nothing else... check and tighten the head bolts, starting with the center port bolt, then the rest in an ever enlarging circular pattern. Also, check the spark plugs for traces of water which would indicate a faulty head gasket.

Your explanation, however, of how the engine is acting now indicates that the carburetor is either set too lean or the carburetor is still fouled. If that engine is equipped with an adjustable slow speed needle valve, back it out slightly 1/8 to 1/4 turn counter clockwise... if the problem persists, I'd suggest double-checking the carburetor rebuild work...remove, dismantle, inspect, clean the carburetor again.

 

[badrano]

The outboard is a 1990 J15RESR. I did some more googling and forgot about the lean/rich knob next to the choke. It was set more to the lean side. I played with it and got some better performance for a bit then is returned to wanting to bog down again when putting it in gear.

I look in to the idle valve and see what happens there.

I'm still assuming my problem last season is that it did overheat. When I got back home, it seemed to run fine.

 

[racerone]

Have you serviced the water pump , yes or no ?------Not sure I understand what it means " seemed to run fine "----Time to do some trouble shooting !

 

[badrano]

Have you serviced the water pump , yes or no ?------Not sure I understand what it means " seemed to run fine "----Time to do some trouble shooting !

The impeller was replaced last year before the season started.

What I meant is that it ran and was not exhibiting the problem I'm seeing now where it dies out. At the time last year when it quit on me, I didn't realized it may have been due to an overheat and I just called for a tow. When I got home, I fired it up.

It is time to troubleshoot it. I'm trying to sell the boat and it will be hard to get top dollar if it's not running right.

 

[oldboat1]

But it's not running right, and you have to troubleshoot some in order to get that top dollar. See if it's overheating. Running in the lake (best) or in a barrel with water about half way up the shaft, use a IR gun on the top of the head. 160F or more is overheating (wouldn't be able to hold your hand on it either.) If overheating, need to check the impeller and potentially check for blockages. Additionally, overheating can bust up a head gasket so you may need to resurface the head cover and replace the gasket. If it's a '90 model, the t.stat is up at the top and an easy replacement -- may want or need to do that.