Switchbox? or Trigger?

[trihull59]

Ok I am trouble shooting my 1975 Mercury Outboard 85hp. I Am now going on my THIRD switchbox on this motor. So I read it might be the trigger. Does the trigger transfer power through the switchbox to the coil ? Also I am not positive on the whole jumper wire tests. ANY INFO would be greatly appreciated!

 

[buzzm19]

Re: Switchbox? or Trigger?

The first step is, does the motor run good when you change the switch box and are you sure its the right one, are the switch boxes new? To part of your question is yes the power to the trigger and when the breaker disc in the dist triggers a signal to the spark box and the spark box fires the coil. I was chasing this problem for a long time and it turned out to be an interment coil, sometimes ran good and others it would misfire and then again no start, sometimes it tried to run backwards. What a nightmare till a friend was looking at the bottom of the metal coil ground and saw a spark jump. If you take the coil off and take the rubber boot off the coil and if the metal around it is broken other than the two pieces going together into it than that's your problem. Hope this helps Buz

 

[Chris1956]

Re: Switchbox? or Trigger?

The switchbox takes power from the red and white +12VDC wires on the starboard side. It stores this power in a capaciter, and when the hall effect sensor in the distributor senses the window in the rotor disk, (it is time to fire the spark plug) the trigger sends a small trigger signal to the switchbox, which causes the capaciter to be discharged into the ign coil.

When you jumper the white and brown distributor terminals on the switchbox, and momentatily connect the black distributor terminal to ground, this simulates the action of the distributor trigger and should fire the switchbox into the coil.

That is the essence of the test. Does it work? if so, the trigger is likely bad or intermittent.

 

[trihull59]

Re: Switchbox? or Trigger?

Well this is what happened last week took it out dropped it in the water wouldnt start. Went out on my friends boat instead came back in went to see if it would start now and then it started 4 hours later? weird. Is the jumper test like hard wiring the white and brown together ?

 

[Faztbullet]

Re: Switchbox? or Trigger?

Sounds more like you have a failing trigger than switchbox...the white wire from switch goes thru the box thru a resistor where voltage is dropped down to supply the trigger voltage

 

[trihull59]

Re: Switchbox? or Trigger?

found the problem thanks for saying that the trigger tells the switchbox when to fire the coil because I have a spare parts motor, switched the dis/trigger assembly out and now she runs like a champ! Anyone happen to know what kind of fluid goes in the lower unit?

 

[Faztbullet]

Re: Switchbox? or Trigger?

80/90w

 

[trihull59]

Re: Switchbox? or Trigger?

thank you