1972 Johnson 125 ignition switch and charging

[danwebster]

hey everyone! I am new to this site but have owned many boats in the past. This is my first outboard ever so I am so lost. I got this boat(1972 sea ray with 125 Johnson motor) last summer for $280 with a 84 EZLOADER galvinized trailer and new fish finder in the box. The bad thing was it was in pieces. I have got almost everything done like new carpet seats etc. I have put most of the electrical together and it now runs. actually it runs great. My problem is it does not charge. Problem number 1: I have put a new Key switch in it and it has 2 mag spots on it but I dont know what to hook up to it. the old switch did not have those spots. problem number 2: the tach has 4 wires...purple, blue, grey and black. as of right now I have the black to ground, purple to accessory + blue to accessory + and grey to the controller harness which goes to the engine and connects to the number 1 terminal on the wire block mounted to engine (it also has one of the stator yellow wire going to it). IS THIS CORRECT because my tach still does not work? I have no charging. I check for voltage at grey wire with engine running and had nothing. I checked at number 1 and 2 terminals with meter set to AC and had nothing. problem number 3: I have a brown wire in the controller which is not connected to anything. also the previous owner had the local shop replace the pulse pack, plugs, coil, wires, cap, piston rings. He showed me the receipts so I took a gamble. any help would be great as I am having trouble reading the wiring diagrams in the service manual.

Dan

 

[Joe Reeves]

Re: 1972 Johnson 125 ignition switch and charging

Ignore the two "M" terminals on the ignition switch. They pertain to a later model ignition system.

Looks like you have the tachometr wired properly. I'd suspect that you have a blown/shorted rectifier. See the following.

(Small Rectifier Description & Location)
(J. Reeves)

On most 2,3,4,6 cylinder engines, the small rectifier is located on the starboard (right) side of the engine just in front of the engines electrical wiring strip. There are a few older V4 engines that have the wiring strip on the rear portion of the engine and the rectifier would be located just under that terminal strip. The smaller horsepower engines usually have the rectifier located on the starboard side of the powerhead close to the carburetor area.

The rectifier appears to be a round object approximately one inch (1") in diameter and also about one inch (1") high. The base of it is sort of triangular in appearance and is attached to the engine with two (2) screws/bolts..... usually one screw/bolt is larger than the other. The rectifier, depending on which one your engine uses, will have either:

One Red wire, one Yellow wire, and one Yellow/Gray wire, or One Red wire, and two Yellow wires.

Note that either of the above rectifiers could have a fourth wire which would be Yellow/Blue

********************
(Small Rectifier Test)
(J. Reeves)

Remove the rectifier wires from the terminal block. Using a ohm meter, connect the black lead of the ohm meter to the rectifier base (ground), then one by one, connect the red lead of the ohm meter to the yellow, yellow/gray, then the red wire (some rectifiers may also have a fourth yellow/blue wire. If so connect to that also). Now, reverse the ohm meter leads and check those same wires again. You should get a reading in one direction, and none at all in the other direction.

Now, connect the black lead of the ohm meter to the red wire. One by one, connect the red lead of the ohm meter to the yellow, yellow/gray, and if present, the yellow/blue wire. Then reverse the leads, checking the wires again. Once more, you should get a reading in one direction and none in the other.

Note that the reading obtained from the red rectifier wire will be lower then what is obtained from the other wires.

Any deviation from the "Reading", "No Reading" as above indicates a faulty rectifier. Note that a rectifier will not tolerate reverse polarity. Simply touching the battery with the cables in the reverse order or hooking up a battery charger backwards will blow the diodes in the rectifier assy immediately.