Bench testing '63 Johnson 75

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Bench testing '63 Johnson 75

Postby Threesheets » Fri Nov 29, 2013 6:26 pm

Hi guys. I've got my Johnson super seahorse electramatic 75hp on a stand with the controls and ignition switch mounted & hooked up on the stand, along with that box that mounts aft with what looks like voltage reg & stuff in it. I've also got the ammeter from the boat mounted & wired in properly. The boat also has an airguide tach and a couple of other goodies on the dash, but I've left them there, thinking I don't need them to test start the engine. I cannot however, get the engine to turn over. I was able to get it to turn over while still on the boat, but now that it's off, no dice. I marked the wires at dissassembly and I'm confident they're correct, I've got slight negative movement on the ammeter when I switch the key on, but it won't engage the soleniod or starter when I advance the key. Any suggestions will be received with gratitude!
Mike
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Re: Bench testing '63 Johnson 75

Postby Ron Zito » Sat Nov 30, 2013 6:55 am

I would start with the basics. Disconnect leads to the starter motor and apply 12 volts directly to the starter motor. If it is energized and runs you now eliminated it as the problem. I had that as a problem with my 1963 Evinrude Starflite 75 hp this last summer. I removed it took it apart and cleaned out all the carbon dust from the worn brushes and cleaned the armature including the segments on the armiture, that solved my problem. Later on that same vacation trip, I had a major failure with the wireing harness between the power control box and the motor. That's a whole other can of worms. I had an electrical fire in the control box. When moving those wires around, which you likely did, the insulation on the wires being old is very brittle. They may have grounded. I am presently remaking my harness as we speak. Ordered cable yesterday. Just shareing my learning experience.

Ron
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Re: Bench testing '63 Johnson 75

Postby Threesheets » Sat Nov 30, 2013 10:58 am

Thanks Ron. I pulled the starter and tested OK. Since I've got movement at the ammeter when I switch it on, doesn't that mean I've got current at least to there? In which case my harness/connections s/b be ok? I'm wondering if I need to have the tach or something else wired into the harness, or that with the engine, control box and controls out of the boat, maybe I've lost a ground or something. Another mystery (see pics): A ground strap from the block to?? The connector is gone from the loose end and I can't find it attached to any nuts or bolts within reach, but looks like it might connect to the clamp where the wiring harness comes through the cowl. Does that make sense?
Thanks again,
Mike

http://i768.photobucket.com/albums/xx32 ... b8d03d.jpg http://i768.photobucket.com/albums/xx32 ... 585b68.jpg
Last edited by Threesheets on Sat Nov 30, 2013 11:06 am, edited 1 time in total.
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Location: Modesto CA

Re: Bench testing '63 Johnson 75

Postby Threesheets » Sat Nov 30, 2013 7:32 pm

SMARTINSEN posted a wiring schem for me over at the WB forum that shows the starter motor grounded to the powerhead. I'm thinking that ground strap connects to the bolt that mounts the starter.
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Re: Bench testing '63 Johnson 75

Postby Ron Zito » Sun Dec 01, 2013 9:51 am

The system has a built in safety logic, it's the throttle and shift control. The shifter must be in neutral and the throttle position must be at an idle speed (below the Start position). If you are outside this range, it should not crank. The ignition loop from the key switch passes thru the shifter/throttle system. This wiring system must be either connected thru the control box or bypassed to start the motor.

The system as you know is simple. The power, positive and negative cables connect from the battery with the positive activated thru the solenoid to the starter motor. The key on thru the shifter/throttle system tells the solenoid to close the circuit and put 12 volts at high amps to the starter motor . The positive cable (red) connects to the terminal on the starter motor and the negative cable (black) connects thru the motor metallic body. There need not be any other ground to the starter motor. The wiring diagram in my opinion is just graphic; I don’t believe a separate ground wire is required. Conditions inside your motor bonnet are a little rough, maybe it might be good to clean up the negative cable connection to the motor body.

-My Evinrude appears to be identical for the most part.
-I don't have such a wire or strap in my set up, and I bought my motor new. Yes, I'm 77 years old. That wire might be an add-on somewhere in the motor's history???
-Running continuity checks on the wires is a way to make sure the wires are OK and are attached properly.
-Here is a link with a wiring diagram (Evinrude) scroll down to the bottom area of the 75hp PDF file, I think it should be very similar to your Johnson. http://www.fiberglassics.com/library/Fi ... ice003.pdf This PDF file has good info about this type motor.

I hope my rambling helps in some way!
Ron
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Re: Bench testing '63 Johnson 75

Postby Threesheets » Sun Dec 01, 2013 11:53 am

Thanks Ron. It's a little rough in there? That's after I sucked the webs & leaves out! If I get this thing running, I'll do a proper cleaning. Anyway, The starter works fine on the bench and on the engine when it was still on the boat, so the connection there is OK. I've got juice to the ign switch and it's functioning properly, so I'll work the circuit from there to the engine. Thanks huge for the service manual link, what a great resource! BTW, your rambling is educational, humorous and always welcome.

Mike
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Re: Bench testing '63 Johnson 75

Postby Threesheets » Tue Dec 03, 2013 1:15 pm

Solved it! There's 4 Terminals on the solenoid: 2 large and 2 small. One of the small takes current from the ign switch to activate the solenoid. The second small goes to a switch at the distributor mounting that trips as the distributor advances/retards (dont know which yet). I had the switch tripped because the dist was turned, so it overode the ign switch. Maybe that's the override switch mentioned earlier? I'm not sure what advances or retards the distributor yet either. Still won't start, no spark, but now I can begin the troubleshooting process.
Thanks all for your time and considered insights, Mike.
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Location: Modesto CA

Re: Bench testing '63 Johnson 75

Postby Threesheets » Tue Dec 03, 2013 9:36 pm

Got it started! Checked the timing marks, tested & replaced the coil this evening, plugged in a gas tank, pumped a bulb & viola! She runs and smokes and smells horrible in a very wonderful 2 strokey, teenagers at the lake bugging Dad for another run before it gets too dark, kind of way.
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