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15 hp Johnson has no power after warming up

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firedog35

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"I have a 1992 Johnson 15hp &#

"I have a 1992 Johnson 15hp (J15ELEN) that has absolutely no power after it warms up. It won't even plane my 14' boat!
Here's what has been done:
1. Carb professionally cleaned and set-up.
2. Replaced main jet with new one.
3. Checked coils for spark when warm & cold.
4. Made sure all ground wires & connections were tight on powerpack, coils and kill switch circiuts.

Does anyone have any ideas or suggestions?
I am leaning towards the powerpack."
 
Also before anyone asks I forg

Also before anyone asks I forgot to mention in the above post that the compression was checked and was #1-120lbs and #2-121lbs.
 
Broken reed valve ????????????

Broken reed valve ??????????????Check to see if it will start run on top cylinder only and then the bottom cylinder only.Test test and test some more.
 
Do you mean start it on one cy

Do you mean start it on one cylinder or start it on both then pull one plug wire off at a time to see if it will run on one cylinder? Also should this be done under load as I cannot test under load unless I put the boat in the water...
 
The motor runs fine when it&#3

The motor runs fine when it's cold and has enough power to plane out the boat?
 
The motor idles like a top whe

The motor idles like a top when warm or cold.
It will plane the boat out when it is cold but it is a little slow to do so. Once it warms up it will not plane the boat out. Also after water testing the boat last night the motor didn't have the power to push the boat onto the trailer with the bunks half submerged in the water.

On the muffs at a medium idle removing the spark plug boot from the bottom cylinder made the engine stall. When the top plug boot was removed it would stay running on the bottom cylinder.
Does this mean I should check the leaf valves?
 
No on the reeds.
I didn'

No on the reeds.
I didn't see where you replaced the spark plugs. Did you do this?
If not change them and try it again.
 
I should have mentioned this e

I should have mentioned this earlier but the plugs are new and have been swapped from top to bottom cylinder while troubleshooting. Also I have installed a brand new set of plug wires and they have also been used on the top & bottom cylinder during troubleshooting.

When the boat was water tested pumping the primer bubble did not make it accelerate nor did pulling the choke out slightly.
 
"Sounds like a failing power p

"Sounds like a failing power pack or even the pick up / trigger coil.

If you can contact Joe Reeves on this site, he may have a test for checking these parts without needing some high dollar tools.

Myself, I have a hard time with on again off again ignition problems without having the engine to use the proper test equipment on.

Good luck."
 
"Thanks charli, so you don&#39

"Thanks charli, so you don't think the reed valves should be checked. I read on another site that at an idle if reed valve is bad carb should spit gas. Do you know if this is true?

Also do you know how I could contact Joe Reeves through this site?
I have read quite a few of his suggestions on other posts and he really knows his stuff!!"
 
"Yes, if a leaf plate (ree

"Yes, if a leaf plate (reed plate) was was faulty, fuel would spit out the carburetor throat with every down stroke of the related piston.

Remove the spark plugs. Test for spark using a spark tester of some sort, not the spark plugs. You need to have a gap set of 7/16" and the spark must jump that gap with a strong blue lightning like flame.... a real SNAP! Does it?

If you have compression and spark as described above, that leaves the fuel system as the problem.

Why was the high speed jet changed, and was it replaced with the same size and type orifice?

The 9.9hp and 15hp models are designed in such a manner that a misadjusted carburetor will affect one of the cylinders, not both, at a certain point.

Perhaps something was overlooked within the carburetor (it happens).

(Carburetor Adjustment - Single S/S Adjustable Needle Valve)
(J. Reeves)

Initial setting is: Slow speed = seat gently, then open 1-1/2 turns.

Start engine and set the rpms to where it just stays running. In segments of 1/8 turns, start to turn the S/S needle valve in. Wait a few seconds for the engine to respond. As you turn the valve in, the rpms will increase. Lower the rpms again to where the engine will just stay running.

Eventually you'll hit the point where the engine wants to die out or it will spit back (sounds like a mild backfire). At that point, back out the valve 1/4 turn. Within that 1/4 turn, you'll find the smoothest slow speed setting.

When you have finished the above adjustment, you will have no reason to move them again unless the carburetor fouls/gums up from sitting, in which case you would be required to remove, clean, and rebuild the carburetor anyway.

Let us know what you find."
 
Joe thanks for your input! The

Joe thanks for your input! The high speed jet was changed because I didn't want to oversize it by cleaning it. It was replaced by a new OEM jet from the dealer (same size #54). I am confident the carb is Ok it has been off twice and the idle was set as you described. Also carb was not dirty when it was initial taken off.
I will try to check spark with a spark plug tester.
 
"Swap the top and bottom coils

"Swap the top and bottom coils, then perform the test you described above. You said pulling the bottom plug caused the engine to stall but pulling the top plug made no difference.

When you swap the coils, if the top cylinder now causes a stall when pulling the plug, then that would mean that coil is faulty and needs replaced.

Also, have you checked to see if maybe the engine is out of timing? Maybe the flywheel key has sheared?

Do the coil swap first. If that does not reveal a problem (i.e. only pulling the bottom plug wire stalls the motor) then I would look at the timing.

KJ"
 
"Top and bottom coils were swa

"Top and bottom coils were swapped during testing as were the wires and plugs. The bottom cylinder still stalled engine. Engine is not out of time, I have checked that and I have had the flywheel off and key was OK. Keep in mind I am doing these tests on the muffs and the engine has no back pressure.

Checked carb again and low speed setting is Ok.
I checked for spark with a spark tester and the spark jumped 7/16" with a strong blue flame. Tried it again after running engine on the muffs for about 10 min. and the result was the same.

Is it possible the engine is not getting hot enough running on the muffs to re-create an intermittant problem with the powerpack, coil etc? Does the engine compartment get alot warmer when tested under load?"
 
Before You do any further test

Before You do any further tests I suggest You get a bucket big enough to get the engine into to get some back pressure. Then do a decarb of the engine.
 
Tested motor in the water till

Tested motor in the water till it lost power.

Spark was very thin and bluish orange on both cylinders although bottom cylinder had a little stronger spark. When spark was tested with a cold engine spark was very strong blue and lightning like.

Swapped wires on coils to see if stronger spark would follow. It didn't so coils look OK.

I suspect the powerpack...
 
"Having a strong blue spark wh

"Having a strong blue spark when cold BUT a weak spark when hot would indicate that the ignition module (powerpack) under the flywheel has failed.

This component is actually a dual component unit consisting of a stator (so to speak) within it to provide power to the powerpack capacitor. When this unit starts to fail, the voltage may be fine when cold BUT when the unit warms up, a voltage drop occurs and the powerpack portion of the unit cannot function.

The cure, if this is the case... replace that ignition module. Notice the aluminum portion of the armature plate upon which the module sits. The extreme top portion has a slight bevel. The vertical portion of the module must align with the inner portion of that bevel to distance it from the flywheel magnets properly.

Larger engine have a seperate stator that provides that AC voltage to the powerpack. When this condition arises, it's a matter of replacing the stator. Let us know how you make out.

http://stores.ebay.com/Evinrude-Johnson-Outboard-Parts-etc"
 
"Thanks for everybodies input,

"Thanks for everybodies input, I have ordered a new powerpack. The stator assembly looks Ok it isn't leaking any honey colored substance anyway.

I just wonder if anybody could explain what the "charge coil & lam assy" does? Is it for charging the battery or does it affect the powerpack and ultimately the spark in any way?

I'll let you know if powerpack solves the problem.."
 
"That seperate charge coil app

"That seperate charge coil applies AC voltage to the rectifier which converts that AC voltage to DC voltage. If an electric start model, the purpose of that would be to charge the battery. If not electric start, it would normally be used to operate lights.

It has no connection to the powerpack."
 
Changed powerpack and charge c

Changed powerpack and charge coil boat ran longer without losing power but still lost power.

I took the boat out until it lost power with air silencer off the carb. When the motor bogged it didn't seem to have much fuel coming out of the nozzle in the carb. When I could get it to run good there was lots of fuel spraying out of the nozzle. Needless to say I brought the boat home and removed the carb and cleaned and carefully inspected it for a 3rd time. It was OK.
I am starting to wonder if have the motor is sucking air somewhere which would reduce the vacuum and then the fuel pump would not work properly.
When I ran the boat in the water and it bogged I tried pumping the bulb from the fuel tank which made no difference. This time when I pulled the choke out the motor seemed to pick up a little in speed.

Does any one have any ideas?
 
Way back it was suggested to c

Way back it was suggested to check the reed valves. What have you done about that simple check???
 
"I was told by two Johnson tec

"I was told by two Johnson techs the problem wasn't the reeds. They said engine would not idle and carb would spit fuel at an idle.
When I had the carb off, I checked visually and they looked nice and flat with no cracks or gaps."
 
firedog35 said:
"I have a 1992 Johnson 15hp &#

"I have a 1992 Johnson 15hp (J15ELEN) that has absolutely no power after it warms up. It won't even plane my 14' boat!
Here's what has been done:
1. Carb professionally cleaned and set-up.
2. Replaced main jet with new one.
3. Checked coils for spark when warm & cold.
4. Made sure all ground wires & connections were tight on powerpack, coils and kill switch circiuts.

Does anyone have any ideas or suggestions?
I am leaning towards the powerpack."
Click to expand...
May want to check the Reed valves
 
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