1972 125 HP Johnson starting problems

[justdoit]

Hy guys, this is my problem. I'm trying to start a 1972 johnson that was resently installed on my 19' footer. It had a 1985 OMC sea drive that was blown. On the "new" motor, it looks that the shifter/throttle cable assembly is different and will only take one cable instead of the two on the OMC motor. Second, I installed a new battery, and i have a selector switch on the boat but only one battery so everything is connected to one; however, when i placed the switch to #1, the starter automatically rotates the flywheel even with the ignition switch in off. I know that i should start the motor in neutral but I don't know how to determine this. Do i have to set the flywheel in a specific position? How can I fix the throttle/shifter problem? Any help wolud be appreciated. Thanks for your time.

P.D. The motor has NOT been started in about 3 years.

 

[HighTrim]

Re: 1972 125 HP Johnson starting problems

Did you not get the remote control for the new motor?

Also go to the FAQ section and read a thread entitled "Awakening a Sleeping Outboard"

 

[emdsapmgr]

Re: 1972 125 HP Johnson starting problems

The 72 was the last year for the electric shift lower units. These engines required a (special) 1972 vintage control box with only one cable for throttle. There is an internal electric switch attached to the control box handle that sends a signal to the engine, telling it what gear to shift to. When the throttle handle is in the neutral position, key on, the lower will be in neutral and you should be able to start when the key is turned to start. To choke, push up (and hold) on the chrome switch lever just below the key switch.

 

[justdoit]

Re: 1972 125 HP Johnson starting problems

I don't have the remote control for the new motor. Any way i can get it? or should i put the motor to sleep? Can I fix something with the controls from the OMC?


Thanks!!

 

[emdsapmgr]

Re: 1972 125 HP Johnson starting problems

These control boxes are still around. Ebay has them on occasion and they are reasonably priced. You can't modify a more modern box to work with that engine. Some boat yards that salvage engines are another good place to start. While the 125 was the high performance engine from OMC for that year, and a solid performer, the achiles heel of it can be the electric shift lower. If it works, you should have a good performer. If the lower needs work, you may have problems finding someone to work on it and parts may be hard to find. If the compression is ok, then I'd look for a box that will work on that engine. Make sure the box comes with the (electric) cable.

 

[tashasdaddy]

Re: 1972 125 HP Johnson starting problems

here is and explaination of the motor.

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.

 

[emdsapmgr]

Re: 1972 125 HP Johnson starting problems

check this item on ebay 320244289340

 

[jay_merrill]

Re: 1972 125 HP Johnson starting problems

check this item on ebay 320244289340

Be careful of this one - if you read the verbage you will note that the seller says that it is for motors that use "the large black plug." While I have seen aftermarket wire replacements for the OMC hydro-electric shift motors that have a black plug, the stock unit has a yellow plug. I sent this seller an email asking him to clarify what he has and have not received a reply.


PS: This very early morning response (its actually 5am where I am) brought to you courtesy of a three year old who doesn't want to sleep ... and doesn't want me to sleep!