1961 40 H.P. Johnson Seahorse runs rough

[Saskatoon2005]

Hello All,<br /> I have a 1961 Johnson 40 H.P. Seahorse and I had a couple of questions about it. It ran perfectly only once out of the ten to twelve times I used it last year. It was the first time I used it. The motor idles nicely (other than needing a new starter solenoid), and when I first put it into WOT it ran nice all the way to our destination. On our return to the dock to pull it out of the water...it started to surge. like it was running out of fuel. like it was starving. So I rebuilt the fuel pump and took the carburator apart and cleaned it twice putting in a carb kit. I used clean fuel on other trips and still had no luck getting the surge to smooth out. Please help me figure this out so I don't have another year of unsmooth boating. Changed spark plugs and still nothing. Put in a new impeller as well and still nothing. Does it sound electrical cause I have not done anything with the elctrical in the way of points, condenser, stator etc. <br /> Thanking you in advance. I love this forum and cherish the people who have helped me in the past.

 

[Paul Moir]

Re: 1961 40 H.P. Johnson Seahorse runs rough

When you get electric troubles, you can feel the troublesome cylinder suddenly cutting in and out. You'll go along at half throttle and then it will suddenly take off, and just as suddenly drop off.<br /><br />Does that sound like it, or is it more of a smooth surge?<br />Did you try pumping the primer bulb when it was acting up? If not, did you happen to notice if there was air in the fuel bowl?

 

[Saskatoon2005]

Re: 1961 40 H.P. Johnson Seahorse runs rough

I go along at half throttle and then it feels like it wants to suddenly take off, starts to, and then goes back into half throttle and switches back and forth between the two sporatically.<br /><br /> I have also pumped the primer bulb and it makes no difference to the sporatic surging.<br /><br /> Does this help at all?

 

[Saskatoon2005]

Re: 1961 40 H.P. Johnson Seahorse runs rough

It also seemed as though the motor drank a ton of fuel. Played a few times with the idle adjustment screw while running at WOT (on the lake), and it made no difference. Please help!

 

[lark2004]

Re: 1961 40 H.P. Johnson Seahorse runs rough

My guess is one of the coils is starting to break down. Might be time to pop the flywheel of and check the coils for any cracks. Also clean and re-gap the points while you're in there.

 

[Paul Moir]

Re: 1961 40 H.P. Johnson Seahorse runs rough

I agree with lark2004, it sounds a lot like an ignition problem. Check to see that you can jump a 3/8" gap with each spark plug, and check the spark plug wires for any signs of cracks as well.

 

[Saskatoon2005]

Re: 1961 40 H.P. Johnson Seahorse runs rough

Hey awesome guys thanks a lot. I was hoping it was electrical as I have done everything i could possibly to the fuel part of it. I bought brand new points and condensers. I will replace them. I also have checked out the coils cost of these and I will replace them too as they have not been changed in many years. Thanks guys and I will undate you when I get all this fun stuff done.

 

[Paul Moir]

Re: 1961 40 H.P. Johnson Seahorse runs rough

marinemanifold.com has good prices on the 18-5181 coils (my favorite). But if they're good I would leave them - the new ones are very reliable.