Mercury Switch

[Meggerd]

Hey I have this same problem I have red stator with attachment everything seems good just bought dva all seems good blue adapter wire goes into switch good got nothing coming out on green wires to coils all triggers tested good. I am new to this boating thing but used cdi electronics troubleshooting guide.

 

[Meggerd]

By the way I have a mercury 75elpto with electric start I see in so.e schematics talk if mercury switch I don't see one. Are where one would be wired into kill circuit I do have atilt position sensor

 

[jimmbo]

The mercury switch you are likely referring to, is to kill the Ignition when the Gearcase lifts up out of the water when an Impact occurs with an underwater object

 

[Meggerd]

Yes but I am unsure if I have one and have looked jus in case. I know I have power from stator to switch box and have triggers to switch box per cdi troubleshoot guidelines but no out green wires on coils I also pulled green wire of coil insure coil not grounded. But that is one expensive switch box

 

[Chris1956]

What year is the motor? Not all Mercs have the mercury switch. Look for an item that looks like a condenser, only plastic, with 2 wires, one of which is grounded to the cowl support.

 

[Meggerd]

It is a1996 75 elpto yes I looked through wiring I did not see one on kill circuit are inline with any ignition parts. I believe my problem is the switchbox it has power in but not out to coils. Ones coming today. Thank you for response if you know a general time mercs used them it would be helpful

 

[Chris1956]

Your motor will have an ADI ignition. The stator supplies all the power to the switchbox. So if the engine is not running, there should be no power to the switchbox.

Also, the switchbox will pulse the coils to fire them. You will not see continuous voltage on the coils.

Mercury switches were used on the 70's and early 80's motors. Not sure when they stopped using them.

 

[Meggerd]

Well thank you again, but the way I am seeing it, mine has a cdi ignition.

 

[Meggerd]

Yes I am getting no pulse out switch box but power going in and triggers passes test. I am waiting on box now

 

[Meggerd]

Oh yes I tested switch box while cranking engine

 

[Chris1956]

CDI is a name for capacitive discharge ignition. The power for CDI can come from the battery or from the alternator. In your case the power will come from the alternator, hence the name ADI ( alternator Driven Ignition).

Hopefully the switchbox is bad.

 

[boscoe99]

CDI is a name for capacitive discharge ignition. The power for CDI can come from the battery or from the alternator. In your case the power will come from the alternator, hence the name ADI ( alternator Driven Ignition).

Hopefully the switchbox is bad.

Huh?

The power to charge the capacitor typically comes from a coil within the stator. The power charging the capacitor is at a much much higher voltage than the voltage that comes from a battery, or the alternator output to the battery. The capacitor voltage when applied to primary side of the coil induces an even higher voltage in the secondary coil which results in a spark jumping across the spark plug gap.

In a battery ignition system a capacitor is not involved. Battery voltage collapsing within a primary coil, due to the current flow in the primary coil being turned off, induces high voltage with the secondary coil, which then passes across the spark plug gap. A battery ignition system does not need an alternator to work. Of course once the power in the battery is depleted then the spark will not longer occur. The alternator is needed to keep the battery powered.

 

[Chris1956]

Boscoe, Mercury OBs from the 70s had a battery driven CDI system, utilizing a Hall-effect trigger. This system pulsed the single coil with high voltage from the capacitor, to induce spark, and had a mechanical distributor. It was different than the battery/coil/points system you describe.

During the 70's Mercury slowly changed their OB lineup over to Alternator Driven Ignition (ADI). In this system, the stator charges a capacitor, and when the trigger signals, the high voltage from the cap pulses the ign coil. These system have 1 coil per cylinder.

The original poster was looking for voltage on the coil, which it will not have until it is pulsed. His meter may be too slow to detect the pulse. He may also think the battery has something to do with his ignition system, which it doesn't.

 

[Meggerd]

Ok thanks my new switch box fixed problem