1982 Johnson 50Hp won’t start

[Ryansmith1]

I recently started working on a 1982 Johnson 50hp J50BELCNR I picked up. Looked like it has been sitting in a barn for a real long time. I put pretty much a new everything on it. Wiring harness, coils, power pack, stator, rectifier, plugs, rebuilt the carbs/ fuel pump, new fuel lines new key switch and kill switch.

Both cylinders have 135PSI, both plugs have a strong blue spark, fuel pump is pumping but this dang motor won’t start. I have got a few back fires and some white smoke but that’s it. New battery and the starter is spinning strong.

If I hold the starter for a few seconds then left off the choke will open back up and some fuel (not a ton) comes out of the carbs. I double check the floats and they are set correct measurements. Both carbs are super clean. I was thinking the read valves were maybe bad so I checked and one of them had a gap letting light in. so I went ahead and put a new set of reeds in and still the same thing. Fresh gas too and that didn’t change anything. New gaskets for the power head, intake Mansfield, carbs, fuel pump and all that.

The only thing I can think of was maybe the lower crank seal is super trashed and it’s sucking air? I pulled the plugs out and put my finger over the holes and turned the motor over by hand and I could feel suction and pressure when the piston moved back and forth for both cylinders.

Also the timing in this motor is fixed based on the crank shaft and the only think that’s adjusted is the WOT timing. Thought maybe that was set wrong but apparently it’s fixed. I have been over wiring diagrams and even traced each wire to make sure it didn’t have a short in it anywhere.

I did all this as a fun learning project and was hoping to have a pretty sturdy motor to use. I have a little experience after restoring a few older motors, but this one has me stumped. Anyone have any suggestions?

 

[saltchuckmatt]

I recently started working on a 1982 Johnson 50hp J50BELCNR I picked up. Looked like it has been sitting in a barn for a real long time. I put pretty much a new everything on it. Wiring harness, coils, power pack, stator, rectifier, plugs, rebuilt the carbs/ fuel pump, new fuel lines new key switch and kill switch.

Both cylinders have 135PSI, both plugs have a strong blue spark, fuel pump is pumping but this dang motor won’t start. I have got a few back fires and some white smoke but that’s it. New battery and the starter is spinning strong.

If I hold the starter for a few seconds then left off the choke will open back up and some fuel (not a ton) comes out of the carbs. I double check the floats and they are set correct measurements. Both carbs are super clean. I was thinking the read valves were maybe bad so I checked and one of them had a gap letting light in. so I went ahead and put a new set of reeds in and still the same thing. Fresh gas too and that didn’t change anything. New gaskets for the power head, intake Mansfield, carbs, fuel pump and all that.

The only thing I can think of was maybe the lower crank seal is super trashed and it’s sucking air? I pulled the plugs out and put my finger over the holes and turned the motor over by hand and I could feel suction and pressure when the piston moved back and forth for both cylinders.

Also the timing in this motor is fixed based on the crank shaft and the only think that’s adjusted is the WOT timing. Thought maybe that was set wrong but apparently it’s fixed. I have been over wiring diagrams and even traced each wire to make sure it didn’t have a short in it anywhere.

I did all this as a fun learning project and was hoping to have a pretty sturdy motor to use. I have a little experience after restoring a few older motors, but this one has me stumped. Anyone have any suggestions?

Are you sure you have the right wire going from the power pack to the proper coil? That would cause a backfire.

 

[Ryansmith1]

Are you sure you have the right wire going from the power pack to the proper coil? That would cause a backfire.

Oh lord, I’ll have to check, but I figured it would be something stupid that I was overlooking. I’ll check when I get home and let you know. Thank you for the suggestion that very well could be the problem.

 

[saltchuckmatt]

Oh lord, I’ll have to check, but I figured it would be something stupid that I was overlooking. I’ll check when I get home and let you know. Thank you for the suggestion that very well could be the problem.

Should be orange wire with blue strip to top cylinder and orange to bottom....pretty sure anyways.

 

[Ryansmith1]

Should be orange wire with blue strip to top cylinder and orange to bottom....pretty sure anyways.

That’s good to know and I think what my problem is. This is the diagram I was using and it dose not specifically say what is what so I never realized. It’s pretty obvious now that you suggested it that there is a set order it would need to go. I don’t know what I was thinning. I’m going to switch them around and try to fire it up tomorrow. I’m willing to bet she runs.

 

[saltchuckmatt]

That’s good to know and I think what my problem is. This is the diagram I was using and it dose not specifically say what is what so I never realized. It’s pretty obvious now that you suggested it that there is a set order it would need to go. I don’t know what I was thinning. I’m going to switch them around and try to fire it up tomorrow. I’m willing to bet she runs.

Not yours but the colors are correct. Orange with blue strip top....orange for lower.

If you had a three cylinder it would be orange with green strip for bottom.

Old omc mechanic taught me this.Think blue for sky...(top) Think green for grass (bottom) works with the trim too.

 

[saltchuckmatt]

That’s good to know and I think what my problem is. This is the diagram I was using and it dose not specifically say what is what so I never realized. It’s pretty obvious now that you suggested it that there is a set order it would need to go. I don’t know what I was thinning. I’m going to switch them around and try to fire it up tomorrow. I’m willing to bet she runs.

Funny, your diagram shows the color coded wire from the power pack but not to the coil, nor does it say which coil it goes to. Also, no legend as to what the wires color codes mean.

I could see how that could mess someone up.

 

[Ryansmith1]

Ok I put the blue stripe to the top and I’m having a different problem now. Motor will slightly run but only when the idle advanced it set all the way to start. Top cylinder seems to not be firing. I swapped coils around and still the same. I pulled the top plug off when the motor was running and it shocked me through my pliers ,but the motor idle didn’t change. Lots of black soot coming out of the motor. Top spark plug is clean but bottom spark plug is black. I hooked a volt meter up and I’m getting a reading on both wires going to each coil from the power pack.

 

[Ryansmith1]

 

[saltchuckmatt]

Ok I put the blue stripe to the top and I’m having a different problem now. Motor will slightly run but only when the idle advanced it set all the way to start. Top cylinder seems to not be firing. I swapped coils around and still the same. I pulled the top plug off when the motor was running and it shocked me through my pliers ,but the motor idle didn’t change. Lots of black soot coming out of the motor. Top spark plug is clean but bottom spark plug is black. I hooked a volt meter up and I’m getting a reading on both wires going to each coil from the power pack.

Bad plug wire?

 

[saltchuckmatt]

Ok I put the blue stripe to the top and I’m having a different problem now. Motor will slightly run but only when the idle advanced it set all the way to start. Top cylinder seems to not be firing. I swapped coils around and still the same. I pulled the top plug off when the motor was running and it shocked me through my pliers ,but the motor idle didn’t change. Lots of black soot coming out of the motor. Top spark plug is clean but bottom spark plug is black. I hooked a volt meter up and I’m getting a reading on both wires going to each coil from the power pack.

With all the unburnt fuel it's bound to be smokey. When you switched coils did you switch plug wires too? Test or switch plug wire.

 

[Ryansmith1]

With all the unburnt fuel it's bound to be smokey. When you switched coils did you switch plug wires too? Test or switch plug wire.

Yes sir I did, I took the whole coil/ wire from the bottom and put it on the top and the top on the bottom.

 

[Ryansmith1]

I also cleaned the ground surface for the top and bottom

 

[saltchuckmatt]

I also cleaned the ground surface for the top and bottom

Do you have an inline or a spark length tester? Check for GOOD spark. Otherwise you will need to go through your wiring I suppose. You might have fried something.

 

[saltchuckmatt]

I also cleaned the ground surface for the top and bottom

Also, if you have a three wire plug, like the one on your wire schematic, make sure a,b and c are all correct from both sides.

 

[Ryansmith1]

Also, if you have a three wire plug, like the one on your wire schematic, make sure a,b and c are all correct from both sides.

A B and C are correct. I did have the orange backwoods before your help. But the grounds are matched and the orange is the orange to ornate and orange/ blue strip to top cylinder. I even pulled the connectors apart and made sure they were clean and seated all the way which didn’t help.

I do have a spark length tester. I’ll have to find it. Any idea how long of a spark should I be seeing? If I fried someting I would guess it’s the power pack?

 

[saltchuckmatt]

A B and C are correct. I did have the orange backwoods before your help. But the grounds are matched and the orange is the orange to ornate and orange/ blue strip to top cylinder. I even pulled the connectors apart and made sure they were clean and seated all the way which didn’t help.

I do have a spark length tester. I’ll have to find it. Any idea how long of a spark should I be seeing? If I fried someting I would guess it’s the power pack?

7/16 spark jump.

Yes, power pack. Did you mess with anything under the flywheel before? And if so is everything lined up correctly?

 

[Ryansmith1]

7/16 spark jump.

Yes, power pack. Did you mess with anything under the flywheel before? And if so is everything lined up correctly?

I replaced the stator. Put the new one on in the same place as the old one. It has set bolt holes in the amateur plate. Wires come down in the same place and everything like the old one. I could pull the flywheel and check everything again.

 

[saltchuckmatt]

I replaced the stator. Put the new one on in the same place as the old one. It has set bolt holes in the amateur plate. Wires come down in the same place and everything like the old one. I could pull the flywheel and check everything again.

Your probably good. Getting past my experience level. Check for GOOD spark and post...let's see if others know where to check next. Would have thought your motor would have been good once wire was corrected.

 

[Ryansmith1]

Alrighty, I’ll check it tomorrow and get back to you. I do appreciate the help!