Reverse only no forward

Joined
Apr 21, 2009
Messages
10
I am working on a 1971 50hp. Neutral and Reverse gears are working, but forward isn't.
I did put in a different directional switch. I have 12 volts to 1 wire for neutral and 12 v going to both wires for reverse and nothing as the motor is supposed to default to forward.
Any suggestions as to which solenoid is messing up or is there something else I should be looking at?
Thanks ahead of time.
 

tashasdaddy

Honorary Moderator Emeritus
Joined
Nov 11, 2005
Messages
51,019
Re: Reverse only no forward

does it have Premium Blend Type C lower unit oil in the lower? if not it may not shift.
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.
 
Joined
Apr 21, 2009
Messages
10
Re: Reverse only no forward

Thanks,
I do have the premium oil in the lower unit.
I will give the wiring a try while cranking the motor over.
If that doesn't work, do I need to start looking at the solonoid or is there something else that could be messed up? Does that shift dog ever stick and not allow things to shift?

Thanks
Jeff the fisher
 

tashasdaddy

Honorary Moderator Emeritus
Joined
Nov 11, 2005
Messages
51,019
Re: Reverse only no forward

the way the lower works, there is a oil pump in it, the solenoids directs the oil to move the clutch dog, there are a lot of things that could just not be totally right causing the problem.
 
Joined
Apr 21, 2009
Messages
10
Re: Reverse only no forward

I just came in from checking the wires. I even removed them from the switch so that there couldn't be 12 volts running to anyplace. When the motor is off everything is in the forward gear. I can't turn the prop without the engine turning over. When I start it without any wires hooked up there isn't any movement of the prop.
Any suggestions? Clutch dog sticking, solonoid sticking?
Help please.:confused:
 
Joined
Apr 21, 2009
Messages
10
Re: Reverse only no forward

When the motor is running I can freely spin the prop on both neutral and forward switch locations.
 
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