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100HP Evinrude 1972?

twoody

New member
I have a 100HP Evinrude Model# 100293R SN# J06943. When the key is turned it does nothing. The battery is good and charged. Will someone please help me! Where do I start to trouble shoot this issue?

Thanks!
 
The neutral safety switch may be out of adjustment.

The 20 ampere power fuse may be blown. Fuse is inline with one of the smaller RED wires leading from the starter solenoid.
 
Your awsome! I found the fuse and replace it. It fired right up after siting for 5 years and ran like a charm.

Thank You!:)
 
Awsome? I don't know about that but my wife has a few other names she calls me from time to time. However, Mom always liked me (grin).
 
50:1 is the correct ratio.

That inline fuse tends to blow when the choke warm-up circuit starts to go. You wind up with intermittently blowing that fuse - that will torture you.

It's an easy fix - one wire to disconnect on engine terminal block. It's been 15yrs since I've worked on that vintage, so I don't recall the exact color wire you need to disconnect from the terminal block- maybe Joe R. can recall.

Basically, there are 2 colored wires going to the choke solenoid(not starter solenoid) and I recall they are purple (ignore the black wire if present). Visually obvious at the choke solenoid mounted starboard side of carbs.

One wire closes the choke completely when choked at the key switch (and key in the run/crank position). You can hear the obvious click when engaged.

The other wire quietly supplies current to a secondary choke "warm up circuit" inside the choke solenoid to automatically adjust the choke as the engine warms up. This circuit was problematic and was eliminated in later versions.

The fix is simple. Disconnect the wire feeding the choke warm-up circuit at the terminal block(tape the end) on the engine.

I want to guess purple with grey, but that's a wild guess.

The simple way is to note the 2 colors at the solenoid and disconnect one at the terminal block. If you no longer get a click from the helm choke when applied, then it's the other one you need to disconnect.

If you can find a wiring diagram online, I can trace it out for you.

The only difference you'll notice is when starting the engine when cold, you may have to blip the choke a time or two after it starts(full choke of course until started).
 
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Oh ya, Type "C" lower unit lube for your electric shift bottom end.

Omc now calls it "Premium Blend Gear Case Lube".

The old style lower unit lube is a must.

Use TCW-III for your 50:1 mix. If you've got old oil hanging around, use it in your weed wacka if you can't bear parting with it...
 
(Temperature Actuated Choke Solenoid Conversion)
(J. Reeves)
Various OMC engines that were manufactured in the later 1960s thru the early 1970s, for example the 1969 55hp Evinrude/Johnson incorporated a dual stage choke solenoid...... easy to identify as they have two wires leading to the solenoid, one purple/white, one purple/yellow.

The purple/yellow is attached at the engine wiring terminal strip to another purple/yellow wire that led to a heat sensor. The initial stage, with the key ON, (purple/yellow), when cold, would keep the choke pulled in half way until the engine warmed up, at which time it would release and open the choke butterfly.

The second stage (purple/white) is attached to another purple/white wire at the engine terminal strip which leads to the choke switch. When the switch was engaged, the choke closed etc.

The problem with this setup is that as the engine got older, the thermostat acted up, water pump became weak, whatever, the heat sensor failed to operate properly and the choke would not release from that half closed position. This would cause the engine to run in a rich fuel mixture condition (flooding, loading up).

The cure to this problem, via a service bulletin from OMC was to remove the solenoid purple/yellow wire from its original location and connect both of the solenoid wires (purple/yellow & purple/white) to the engine wiring harness purple/white wire at the engine terminal strip.

The above change would allow both solenoid wires to be energized when the choke switch is engaged, pulling the choke butterfly in firmly..... and only when the choke switch is engaged.
 
O.k. guys I thought I had all the bugs worked out but I have a new issue now. The motor wont go into neutral via the button next the shifter. I have a foward, neutral and Reverse. I have not tried the reverse cause the motor is moveing to fast to shift into reverse. The button push's down just fine. Any ideas? :confused:
 
Motor is in forward gear by default. You need voltage to the green and blue wires that go down to the shift solenoids in order to shift out of forward. I believe it works like this:

No voltage = Forward (default)

+12V to green = Neutral
+12V to green AND blue = Reverse

There are several points of failure, so first test to see that you are getting 12V from the control when you press the N button and the R button. If that is the problem, then you can force the motor to shift by applying 12 V directly to the green wire while the motor is turning and watch it go into neutral, apply 12 V directly to the blue and green and see it go into reverse. If it ain't working, then something may be wrong in the gearcase (solenoids are bad, blocked oil passages, ect)

-E
 
(Hydro Electric Shift System Explained)
(J. Reeves)
The shifting setup of the lower unit is what's called a "Hydro Electric Shift", which is quite complex consisting of voltage being applied to solenoids in the lower unit which in turn change oil passages via a oil pump that supplies various pressure on a spring loaded shifter dog. The wires leading to the lower unit (at the powerhead) are "Green" and "Blue". The engine must be running or cranking over in order to shift out of forward gear.

You CAN NOT use HI VIS lube in that lower unit. You MUST USE what OMC calls "Premium Blend" lube, commonly called "Type C". (A thinner lube)

Note: The engine must be running OR have the driveshaft turning by some other means in order for the engine to shift.

In neutral, you need 12v to the "Green" wire.
In reverse, you need 12v to both wires, the "Green" one and the "Blue" one.
In forward, there should be no voltage to either wire. (The spring loaded shifter dog forces the unit into forward gear)

To check the lower unit for proper shifting to make sure you have no trouble there, remove the spark plugs to avoid problems and to allow a higher cranking speed.

This next step eliminates the actual shift switch in case problems may exist there.... Disconnect the blue & green wires at the knife connectors (the rubber insulated boots) leading to the lower unit at the powerhead, then using jumpers, take voltage direct from the starter solenoid to apply voltage to the "Green" wire for neutral, then both wires 'Green" & "Blue" for reverse (Remember the engine must be cranking over in order to shift).
With no voltage applied, the unit should be in forward. No need for a ground jumper... the lower unit's already grounded. You may crank the engine with the key switch or by energizing the starter solenoid with a jumper wire.
 
I think the key switch is bad. It keep blowing that 20amp fuse and while I was going down the lake the starter keep runing like the key was stuck on. There is shavings on the starter where it was grinding. I have ordered a new one off this web site and well see if that works. Do you thing that could also effect the motor not going out of gear?
 
To joereeves. I think you may have solved a headache I've been having with this same engine. Always starts fine, and I can idle out of the no wake zone, bag it and it planes out in 4 seconds, then runs perfect around the lake. When I stop to drop a skiier and idle for two minutes, it falls on it's face the next time I hit the throttle. I have always wondered two things on this motor - 1. Why is my choke already pulled in when I turn the ignition on, and 2. - What the hell is the little sensor on top of the block. I knew it must be a temp sensor but since there's already one in each head, I had no idea what it was for. I'm trying this out tonight, if the rain stops.

Thanks a bunch!
 
Twoody.... starter cranking with the key OFF = faulty starter solenoid.

Tlestan.... glad to hear that my notes have done some good for you.
 
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