1956 Johnson 30hp

[30hpbob]

After bebuilding the carburator (which I thought was the problem) I still have no power when I give it full throttle. It will start but idle rough, put it in gear and take off but only goes 5 knots top speed. Looking for some suggestions that may help me out.

 

[jbjennings]

Re: 1956 Johnson 30hp

You have weak, none, or intermittent spark on one cylinder is my guess. check spark with an actual spark air gap tester. If it won't jump 1/4" with a hot blue spark, it's not enough.
JBJ

 

[30hpbob]

Re: 1956 Johnson 30hp

You have weak, none, or intermittent spark on one cylinder is my guess. check spark with an actual spark air gap tester. If it won't jump 1/4" with a hot blue spark, it's not enough.
JBJ

Thanks JBJ. If that is the case and I am only running on one cylinder than what would you suggest the next step would be.

 

[mstahl1171]

Re: 1956 Johnson 30hp

Replace coils, points, condensors and maybe spark plug leads. If it were me I would replace all. Parts are available here on iboats and dealers.

 

[30hpbob]

Re: 1956 Johnson 30hp

Replace coils, points, condensors and maybe spark plug leads. If it were me I would replace all. Parts are available here on iboats and dealers.

Thanks for the help, I will replace them all.

 

[tonk62]

Re: 1956 Johnson 30hp

you need to also check the cut out switch, it may be preventing spark on one cylinder

 

[30hpbob]

Re: 1956 Johnson 30hp

you need to also check the cut out switch, it may be preventing spark on one cylinder

Not sue what that is or where it's located.

 

[1946Zephyr]

Re: 1956 Johnson 30hp

The cutout switch will have one wire going to it, from your magplate and it's mounted on the powerhead itself. If you unhook the wire from it, then try running your motor. Personally, I'm with JBJ. You likely have a pair of antique coils in need of replacement and yes, I would definately replace all that mounts on that magplate and you won't have to mess with it for many years to come.

 

[30hpbob]

Re: 1956 Johnson 30hp

The cutout switch will have one wire going to it, from your magplate and it's mounted on the powerhead itself. If you unhook the wire from it, then try running your motor. Personally, I'm with JBJ. You likely have a pair of antique coils in need of replacement and yes, I would definately replace all that mounts on that magplate and you won't have to mess with it for many years to come.

Lot of good information, thank you. I guess I will start by replacing it all.

 

[1946Zephyr]

Re: 1956 Johnson 30hp

I would post back what your coils look like before you buy new ones. Often times people replace coils without new wires and the shove the old wires into the new coils, without trimming off a little on the end. When this happens, often times connection is lost, because of the corrosion caused from the last set. I usually replace wires each time I replace coils, but if I find the originals look good, then I would just trim off 3/8" of each end and create a fresh new connection. Most people fail to do this when they replace coils.