1967 Johnson 9 1/2

Papa G · Mar 17, 2009

I need some advice on my 9 1/2 . Johnson .It seems that after fishing all day and we go back to the dock which is quite a bit aways from the fishing hole. It does not have the power like it did when we started out in the morning(ME too but thats another story) Weight capacity is not a problem we are well under the weight limit for fish and people.

BIGcarpy50 · Mar 17, 2009

Re: 1967 Johnson 9 1/2

rings, seals, could be bad..when old motors heat up then cool off i have heard that they lose power. just my opinion....

Rick. · Mar 17, 2009

Re: 1967 Johnson 9 1/2

Hello. It could be a bad coil that fails when it heats up. Next time you notice the problem, pull your plug wires one at a time. If when you pull one your motor stops, you will know your running on one cylinder. 9.5's run really smooth on one cylinder but the top end speed would have to suffer. Also your plugs could be a little fouled after a lot of trolling but running at full throttle should clear them fairly quick. I'm betting on a bad coil. Good luck. Rick.

Papa G · Mar 28, 2009

Re: 1967 Johnson 9 1/2

I ran the motor for some time in a barrell, pulled the top plug and the motor stopped. Put the plug wire back on and restarted the motor, pulled the bottom plug and the motor slowed down some but ran smooth. Coil or bad rings? What do you think?

CATransplant · Mar 28, 2009

Re: 1967 Johnson 9 1/2

Yup. The top cylinder is firing, the bottom isn't. Could just be a bad plug, so start there. Pull that plug. Is it fouled? If so, put in a new one (might as well change both), then repeat your test.

If the result is the same and it only runs on the top cylinder, then it's time to pull the flywheel and replace what's busted. Fortunately, you have the old standard magneto, so all the parts are available and cheap.

Rick. · Mar 28, 2009

Re: 1967 Johnson 9 1/2

Hello. I'm thinking COIL, bad points, condenser, bad plug, bad plug wire but not rings. Have you ever replaced the coils? what do they look like. If they have cracks then they should be replaced. Start it up in the dark and you may see spark jumping from plug wires but I think a couple of new coils is in order. Best of luck, By the way, it is never a bad idea to check your compression but only so you know what it is. Your compression won't be the reason your motor shuts down when you pull the plug wire. Rick.

Papa G · Mar 28, 2009

Re: 1967 Johnson 9 1/2

Does each plug have a coil?. Remember I'm new to this type of work. Is there a diagram avaiable to get an idea what I'm looking at?

jbjennings · Mar 28, 2009

Re: 1967 Johnson 9 1/2

Check the "top secret stuff" thread on the top of this forum for some step by step instructions--with pics.

We won't even have to kill you if you read it.
Enjoy,
JBJ

Rick. · Mar 29, 2009

Re: 1967 Johnson 9 1/2

http://shop2.evinrude.com/ext/index.aspx?s1=388dda0bb6badbcdd10f6ac17c163f07
You can look here at any evinrude 9.5 from 68 - 73. They didn't change very much. Two coils, points, condensers, etc. Look for the drawing for the magneto and it will show you what you have. As it was said, go to the Top Secret link to get instruction. Just please, don't tell anybody you were in there with out a clearance. Best of luck, Rick.

Papa G · Apr 9, 2009

Re: 1967 Johnson 9 1/2

Replace plugs, the bottom one looked fouled. Did the check again and things went well,both plugs are fireing now. Is there anything that will keep them from fouling?

ezeke · Apr 9, 2009

Re: 1967 Johnson 9 1/2

To reduce fouling:

If you troll a lot, try having the gap on your J4C plugs at .040 rather than .030;

Make sure that the thermostat is functioning properly;

Use synthetic TC-W3 or synthetic blend TC-W3 oils plus a carbon treatment. BRP XD-50 is a good synthetic blend with a carbon treatment built-in;

Prop the motor for your average load and use so that you can reach 5000 RPM max at WOT.

Rick. · Apr 9, 2009

Re: 1967 Johnson 9 1/2

Give your motor a good run when your done trolling. That will help clean up the plugs for your next trip. It will also help clean out the exhaust of accumulated oil. Rick.

Papa G · Apr 10, 2009

Re: 1967 Johnson 9 1/2

How about changeing to the J6c plug,is it not a hotter running plug?

iwombat · Apr 10, 2009

Re: 1967 Johnson 9 1/2

There may be a recirc valve on that motor ('67 or '68 introduction I think) that is marginally functional and almost a good idea. If it's clogged it may be dumping excess fuel into the bottom cylinder. Wouldn't hurt to take it off and clean it out. You'll find it at the bottom of the intake manifold.

1967 Johnson 9 1/2

Cadet

Petty Officer 1st Class

Captain

Cadet

Admiral

Captain

Cadet

Captain

Captain

Cadet

Supreme Mariner

Captain

Cadet

Captain