68 Evinrude 55hp Hydro-Electric Shift jumping forward when shut down

[northface]

When I shut off the key the gearcase kicks into forward. I know that when the ignition is turned off, 12V is provided to green/blue wires to keep it neutral until the flywheel stops turning. This happens when the red lead from the rectifier supplies 12V back up through the push button remote. I've tested the rectifier diodes and they all test ok. Everything else appears to be ok. I'm stumped. The only thing I can think of is when I test the rectifier, red lead output, I get an erratic reading. I'm not sire if that's because I'm using a digital meter or if something else is wrong.

 

[racerone]

Here is what happens on them.------12 volts is provided to green to keep it in nuetral.----------If it is an original 68 motor there will be a vacuun switch with a rubber diaphragm on starboard side of the motor.

 

[northface]

Maybe I'm confused. This is how I thought it worked. There are two ways 12V is supplied to the diaphragm. One is through the ignition switch, the other is through the rectifier. When you crank the engine the diaphragm completes a circuit and 12V from the battery continues to keep it in neutral (this works). When you shut off the ignition the 12V from the battery is cut off. Now you are depending on the 12V from the rectifier to keep it in neutral. Since the engine is still turning there is still a vacuum and the diaphragm is completing the circuit. This is when it kicks into forward. Leading me to believe that something is wrong with charging output....maybe. No clue :-(

Am I wrong about the way the diaphragm works.

 

[northface]

Crud, I see it now. The connection needs to always be from the battery and the rectifier.

 

[F_R]

No Title

By "rectifier", you are referring to the blocking diode, right? When ignition key is on, primary feed to the shift switch is through the blocking diode. When key is turned off the vacuum switch continues to feed the shift switch from the battery, till engine coasts to a stop. Charging circuit has nothing to do with it.

 

[northface]

No, I meant the rectifier. But yes, I realized in a "duh!" moment that the vacuum switch is connected to both the battery and the output of the rectifier. So this means there is always 12V to the vacuum switch. Therefore, either the vacuum switch is not working or a wire is not connected back to the shift box. As soon as I have time to dig in I'll post back what I find.

 

[racerone]

Do you hear the solenoid click when you push on the diaphragm ?---Is the metal disc on the diaphragm ?

 

[northface]

Yes, it clicked and I tested the lead into the green wire to make sure it was providing 12V. I took the diaphragm apart, because I couldn't think of what else to do ....that's when I figured it out. The rubber cover had a slight tear in it. Small and close to the edge so it was really hard to see.