1975 50hp ingition and wiring questions.

[bonz_d]

Just finished looking at a 1975 50hp Johnson that I'm looking at buying of course. Yes it's been sitting for an unknown amount of time so we hooked up a battery and jumped the starter to do a compression test and unbelieveably we got 150psi on both cylinders. Next went to check spark and there was none on either cylinder.

Question is does this need power to the igintion before it will produce spark or should there be spark by just jumping the starter soleniod? Both ends of the red plug are present but the ignition switch has been cut off. I have a switch here at home if that matters.

I did do a search for this and after 4 pages I still couldn't find this answer or maybe my key words were wrong.

Thanks as always!

 

[Will Bark]

Re: 1975 50hp ingition and wiring questions.

I don't know about your motor but on a 1976 70 hp Johnson, the ignition switch must be on to produce a spark. Good luck

 

[bonz_d]

Re: 1975 50hp ingition and wiring questions.

That's what I'm thinking also but just want to see if I can find out for sure. Supposed to pick it up Saturday.
Just priced out igintion parts for this and 2 coil, rectifier and power pack is $300.00+ so I see it could get pricey on a cheep budget.

 

[eavega]

Re: 1975 50hp ingition and wiring questions.

You can take the ignition switch out of the picture by disconnecting the black/yellow wire from the power pack. This should be done with the plugs out to test for spark. The Black/Yellow wire will ground out the ignition. If you get spark at that point, you have a bad switch. If still no spark, then I suggest you go to CDI Electronics webpagage and look for the troubleshooting guide they have there.

Rdgs

 

[bonz_d]

Re: 1975 50hp ingition and wiring questions.

You can take the ignition switch out of the picture by disconnecting the black/yellow wire from the power pack. This should be done with the plugs out to test for spark. The Black/Yellow wire will ground out the ignition. If you get spark at that point, you have a bad switch. Rdgs

Right now there is no switch. Just wire ends. So this blk/yl wire at the switch is it normally open or nornmally closed? With the blk/yl wire not connected to anything at the switch does it still ground out the ignition? And yes I do have a spark tester.

 

[boobie]

Re: 1975 50hp ingition and wiring questions.

Disconnecting the blk/yl wire from the pack is normal run position. To stop the mtr you ground it out.

 

[F_R]

Re: 1975 50hp ingition and wiring questions.

It should have spark with the wires cut off, if they are not touching anything. DO NOT allow any battery voltage to contact the black/yellow kill wire, as that will destroy the power pack.

It is "ON" with the black/yellow wire disconnected, and "OFF' if the wire is grounded.

 

[bonz_d]

Re: 1975 50hp ingition and wiring questions.

OK,then here's were I'm at. Also talked with my boos last night at work and he said his 115 Johnson will not run w/o power going to the power pack and w/o a switch it will not get spark but agreed that the black/yl wire being cut off should be the same as removing it from the power pack.

Now I read F_R's response and still don't know what I'm doing. Let me ask this way. If the red electrical plug is disconnected inside the engine should it get spark by just jumping the starter solenoid?

 

[boobie]

Re: 1975 50hp ingition and wiring questions.

Depends on what mtr your boss has.

If the red plug is disconnected you should have spark. You're just eliminating the boat wiring harness. Could still have probs with the power pack,stator and ect.

 

[bonz_d]

Re: 1975 50hp ingition and wiring questions.

This engine just arrived to it's new home. Will have to set up a stand and then the trouble shooting can start. I'll post as I go along as I am sure I will have many more questions.

 

[bonz_d]

Re: 1975 50hp ingition and wiring questions.

Got this set up and wired in a switch. Hooked up a battery and gave it a crank. After a couple turns I had spark on the top and then it quit. Never seen any spark from the bottom cylinder. Then after looking it over it appears that the wire that should have the fuse in it has been cut and butt connected together. So that's one thing for sure that's going to need to be fixed.

Thoughts?

 

[bonz_d]

Re: 1975 50hp ingition and wiring questions.

Looking at service manuals for this and came across a few for the Evinrude 50hp. I believe these engines are the same but is there any difference in the Johnson and Evinrude manuals?

 

[bonz_d]

Re: 1975 50hp ingition and wiring questions.

Well I've got an original OMC Johnson manual on the way so If I get this figured out I'll let ya's know.

 

[bonz_d]

Re: 1975 50hp ingition and wiring questions.

Well the new manual hasn't arrived yet I was able to get out today and get this engine set up on a stand. Went through and checked out the wiring somewhat, looking for broken or loose wires and connections and all looked good.

Reconnected the battery. Connected the spark tester to the top cylinder and cranked it over again. WOW! Terrific bright blue spark!!! Tested the bottom cylinder and again a terrific bright blue spark. Why no spark previously I still don't know.

Tomorrow I will connect the muffs and some fuel and see if it will start. So a good end to a horrible week which included another stay in the coronary unit for a couple days. Now for some rest and I'll post what happens with this tomorrow.