Question about hydroelectric shift

[eavega]

Hey folks!

I have a 1972 50 HP Evinrude Lark (Model 50273C), which I am trying to get running. I finally got around to trying to start it, and I was unable to. I get a good spark with a tester, the motor had good compression, fuel is flowing freely from the tank to the carburetor, so I am suspecting the carbs are fouled and will be removing them for cleaning and rebuild this week. I did have a couple of questions I hope you all can answer for me.

While trying to start it, I noticed the propeller spins. I know that the default on this motor is forward gear (no voltage on the shift solenoid). When the power is off (key removed) the propeller spins as expected with the flywheel when turned by hand. For all the other outboards motors I have owned, the start procedure is to start them in neutral. My question is, does the motor go to neutral when you turn the key to power the system if the neutral button is pressed on the control? Also, can you operate the gearshift buttons when the system has now power i.e. is the gearshift just a one-of-three toggle switch? Last question; will the motor start if it is in gear?

-Eric

 

[tashasdaddy]

Re: Question about hydroelectric shift

what i have found, is if you turn the key, press neutral, the motor will 1st go ingear, and immediately come out. also when you shut the motor down, you will feel it default to forward. i suggest when testing the motor, to remove prop, just for safety.

Hydro Electric Shift)
(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)

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.

 

[eavega]

Re: Question about hydroelectric shift

Thanks for the info Tashasdaddy. A couple more question about this motor. The shift may be electric, but the throttle is still mechanical right? A cable that pushes and pulls the throttle mechanisms. If the system is not powered, I should still see the throttle advance when I push or pull the control lever, right?

Also, I see in the service manual a mention of a "safety switch", but I can't find an image of it anywhere, just a hand drawing of where it fits into the electrical system. The service manual does mention that failure of the safety switch would be a reason for the motor not starting, but it doesn't show you where it is. Any suggestions?

-E

 

[rayodunne]

Re: Question about hydroelectric shift

Your throttle is mechanical and is controled using a cable. This cable has adjustment so it should be set right or you will not obtain either top rpm or bottom rpm depending on which way it is out of adjustment.

On your motor the safety switch is located behind the throttle arm on the motor. Unless your throttle arm is in the right position the engine will not start.