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1985 Evenrude no charge, no start

Loren Cadenhead

New member
owned this lil 70 hp for 2 years stopped at the end of a good day, then wouldn't restart battery dead had to jump it, then checked, no fire to the plugs? could someone idenify problem from symptoms, or maybe tips on how to troubleshoot? Have a little mech. skills. brought the engine back to life after sat for years, but am stumped on this one.
 
First check the charging rectifier as follows, BUT before installing another one if needed, be sure to check the polarity at its RED wire terminal.... it must be positive (+) polarity.

(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.

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Now, remove all of the spark plugs. Rig a spark tester so that you can set a 7/16" gap for the spark to jump. The gap is important. If no spark, disconnect the large RED electrical plug at the engine, then crank the engine by jumping the starter solenoid (Bat solenoid connection to small 3/8" nut engagement terminal). If you now have spark, the problem is usually a shorted ignition switch.

However, before you start replacing parts, look closely under the flywheel. That stator (large ring) is the beginning of both the ignition and charging system. If it is cracked and/or dripping down a sticky looking substance upon the timer base and powerhead, replace that component first. Let us know what you find.
 
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