Logo
FULL SITE MENU

Engine runs ruff and smooth

C

cws68

Member
Ok been working on this 1962 Johnson 40 HP and been running ok but not great. Sat for 25 years. Now notice fuel in water and sure enough fuel lines needed changing. Matched all up and made the same as before. Now the motor runs but can't get a good idle nor high speed is never the same. Today the engine opened itself up it seemed and was cruising awesome but only a couple of times. Some times it would bog down some and not regain speed. Idling is rough even when I adjust lean it starts to smooth out then gets choppy again. When I throttle up it at times she hesitates and must be done slowly but don't always get the high speeds again.

MY QUESTION IS... Could this be a fuel pump problem?
I love this thing and wish to keep it a live
 
You could check fuel pump by squeezing primer bulb while it's acting up to see if symptoms are subdued. Just came in from the shop....be snowing here in a couple days, but still working on motors.....trying to finish a few customers. This 6 horse is acting the same way. Great spark, jumps 1/2". Gotta be carb. Your spark should jump 3/8". Nice blue/white "crackle". If that's good, then it could be carb. If that's been rebuilt, then it could be spark plug wires. Sometimes they will arc to ground in cramped places under the stator plate......but a spark test will be normal. This plug wire problem can be hard to diagnose because one wire will arc at unpredictable intervals.
 
If you have not checked the coils on that 1962 motor, you are wasting your time until you do. You can almost bet the farm that they are cracked unless they have already been replaced. And yes, cracked coils can cause the kind of griefs you are describing.
 
fdrgator said:
If you have not checked the coils on that 1962 motor, you are wasting your time until you do. You can almost bet the farm that they are cracked unless they have already been replaced. And yes, cracked coils can cause the kind of griefs you are describing.
Click to expand...

Wires were cracked in spots used tape on them but never replaced. Never thought about coil since i had spark. New to all this

Thank you
 
Carb never rebuilt that I know But will be checking spark out more for now. But wires for sure need replacement. Taped over some cracks.

Thank you.
 
fdrgator said:
If you have not checked the coils on that 1962 motor, you are wasting your time until you do. You can almost bet the farm that they are cracked unless they have already been replaced. And yes, cracked coils can cause the kind of griefs you are describing.

Think I found my problem trying to upload. Wires were ok EXCEPT a nick in wire under holder
Click to expand...
 
Last edited:
timguy said:
For photos, reduce size to under 1000k....then they go through.
Click to expand...

I do believe I found problem. Was hiding under old wire holders wire1.jpg
 
Good job. Can you get a photo of the coils too? They have likely been replaced, as Gator mentions. As Joe Reeves reminds us, make sure you "screw" the new copper core wires onto the coil pin/barb. I'm restoring a 1972 40 horse over the winter. Probably will replace wires too. Why? They get brittle from age....draging on the stator movement and eventually cracking or rubbing through.....because they are too stiff.
 
Back
Top