1972 50 hp Evinrude w/ hydro-electric shift

bybb101

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Mar 6, 2013
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4
Hello fellow boaters, I am fairly new to boating, and new to the iboats community. I am getting ready to repair/rebuild my first outboard motor. I have a 1972 50 hp evinrude model # 50273-c, with the hydro electric shift system, I also have the control box, but I do not have the key. Before I go sinking alot of money into rebuilding the control box I would like to get the motor to crank over, fire off, and maybe even running for a minute. My first (?) is there a way I can start the motor with out the control box, or atleast bypass the key-lock assembly. The control box is in pretty rough shape and will need to be rewired, I will also need a wiring digram of the key-lock assembly, and the forward, neutral, reverse switch. There are also 2 wires one tan, and one purple the tan one runs from the wiring harnes to the motor, and the purple one from the key-lock asembly. They run through a plastic sleve to the front of the control box but whatever they ran to is not there could someone please tell me what is missing. I would appriciate any and all insight, input, and assistance. Thank You
 

F_R

Supreme Mariner
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Jul 7, 2006
Messages
28,195
Re: 1972 50 hp Evinrude w/ hydro-electric shift

Just order a new key from an Evinrude dealer. Meanwhile, disconnect the black with yellow stripe wire from the power pack and it will start and run, either by jumping the starter or rope starting it. Warning, everything else must be connected or you will blow the rectifier. The wires coming out the front of the box probably are added by somebody for a tachometer.
 

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eavega

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Apr 29, 2008
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1,377
Re: 1972 50 hp Evinrude w/ hydro-electric shift

bybb, I don't want to be "that guy" that tells you that this motor is probably not worth sinking a lot of money into, but this motor is probably not worth sinking a lot of time and money into. If you picked up an early 70's hydro-electric shift motor in running conditions that needed some minor work like carbs, fuel pump, etc. i'd say go for it. Otherwise, I can tell you the control boxes are hard to come by, as are the shift solenoids. The shift system is temperamental and does not take well to any water intrusion or letting LU oil changes go too long. It also requires a special type of LU oil (Type "C") which can be difficult to source.

That having been said, search the iBoats site to find a schematic for wiring up your own shift switch. Note that (again IIRC) the home-brew switch does not have any protection from throwing the motor from forward to reverse while at full throttle. If you happen to inadvertently do that, you will cause some major damage to the motor.

By the way, I believe the tan wire is your overheat alarm wire. It connects to a piece that expands with heat, and when it get hot enough it closes a circuit which will will sound the overheat alarm in the control. Purple is generally a hot (+12V) key-controlled ignition wire.

To crank over the motor, you can jump the starter solenoid, and it should crank. I think (and someone will correct me) that you still need to disconnect the ignition ground (black/yellow wire in the power pack) to get it to actually start. Be warned, though, that you will not have any way to shut the motor off other than re-connecting that black/yellow wire.

Rgds
 

bybb101

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Mar 6, 2013
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Re: 1972 50 hp Evinrude w/ hydro-electric shift

Thank you fellas for your input so far, the digram has been very helpful, I can see by the diagram that the purple and tan wires I asked about do go to the hot horn. I also have come to the conclusion that the control box is not in as bad of shape as I had origanlly thought. the throtle cable is set up, easy fix, or replace. and the key is missing. After taking out and cleaning the forward, neutral, reverse switch it seems to be in good working order. However when I took off the cover of the control box, and removed the throtle cable most of the wires to it pulled lose and I can not find the wiring diagram to put them back where they belong. I got this motor from a friend who moved out of town, he had it running about 3 years ago, so I believe with a little work I can make it run again. In doing research on this particullar engine I have heard many good as well as bad things about them so I can only assume it is like buying a used vehicle, sometimes you get lucky, and sometimes you get a lemon. I do know that it is worth a good bit more running, so getting it to fire is the only way it will be worth more than scrap price to me.
 

bybb101

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Mar 6, 2013
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Re: 1972 50 hp Evinrude w/ hydro-electric shift

Okay so I am making some progress, I have gotten the throttle cable freed up, and working good. I have cut off about a foot of the wiring harness into the control box and have good wires there, they all have brand new ends on them. I have 5 wires left to hook up, I know they all go to the forward, neutral, reverse switch. The switch seems to be in good working order. I have inspected it, and done some research the switch has 5 tabs on the bottom of it. they are layed out as follows from front to back.

2 R N
1 +

The switch is a GE ASP 3124-97, I know the green wire runs from the neutral shift solenoid, and would guess it runs to the N connecter on the switch. The blue wire runs from the reverse solenoid, and I would guess the R connecter on the switch. The two white wires run the neutral saftey switch, one runs from the S connecter on the key-lock assembly. The other white wire runs back through the wiring harness to the starter solenoid, and to the saftey switch. I would guess that they run to the 1 and 2 connecters on the switch. which leaves the purple wires one solid which runs from the A connecter on the key-lock assembly, and the other purple with green which seems to run throught the wiring harness to the motor, through the terminal block and to diode and lead assembly. which if the rest of my speculations are correct would half to run together and to the + connecter on the F,N,R switch.

These are my best educated guesses, If anyone could please provide me with any input, insight, feedback, or a wiring digram of this switch and the way the wires connect I would be greatful. This is now all that is keeping me from trying to crank the motor, as I was told not to start it without all the wires hooked up, except the black and yellow one, which I will put on a toggle switch to be able to complete the circut if it dose start and wont shut down.

F,N,R switch.jpg


Here is a picture of the connecters on the switch I am working with. Please Help
 

F_R

Supreme Mariner
Joined
Jul 7, 2006
Messages
28,195
Re: 1972 50 hp Evinrude w/ hydro-electric shift

If I am reading you correctly, you got it right. Yes, purple and purple w/stripe go to same + tab
 

bybb101

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Joined
Mar 6, 2013
Messages
4
Re: 1972 50 hp Evinrude w/ hydro-electric shift

If I am reading you correctly, you got it right. Yes, purple and purple w/stripe go to same + tab

Okay thank you for the confirmation, I only need to know which white wire goes to what connector, or how much of a difference it really makes. Thanks again bybb101
 
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