50 hp mercury 2 stroke Weird problem help needed

[wetaline]

I have got a 1984 2 stroke mercury. It has been a great one, but now I have an issue with starting. I can put the boat in the water and it fires right up,but after running up the river and killing it, most of the time it it won't start back up. I mean won't start. I will crank and crank, let the starter cool off and crank some more, it willmsfart up but takes a while of floatin down the river. Today I took the carbs off and cleaned them, checked the jets and floats and all seemed fine. I disconnected the tilt switch and checked the spark and had it. I noticed something weird while testing I had 275 volts on the black wire with a yellow stripe while it was running. I know that test isn't a conventional way to test I guess but after reading it I ohmed it at 0.8 ohms. This black and yellow striped wire is on the switchbox and from wat I understand it shorts the ignition to kill the motor. I will say that I have yet to see no spark but my testing has been done at the house. Anybody seen a problem like this? The good news is that I can start it run up river and if it won't start I can just float back down to the ramp, so I still been Fishin. I need help on this one. We plan to get a new boat soon but I still want this one runnin right it's all I got right now. All help would be appreciated.

 

[buzz]

Send wrenching a PM.

 

[Bubbakat]

The wire you are taking about should never have current to it. Check the ing switch Next time it happens take the wire loole ans see if it fires if it does replace the ing, key switch.

 

[wrechin2]

The only portion of your igntion capable of making that kind of voltage is the stator. If you have that kind of voltage on that wire that would mean you more than likely have a internal issue with the switch box. I replace many switchboxes for a blocking diode going bad and double firing a cylinder causing a engine failure. Usually it will be 5-10 Volts when they are bad. That is because the trigger voltage is making it to the "kill" circuit through the bad diode and triggering other cylinders because of the path of least resistance is another SCR. When you turn the switch on it opens the circuit and should not have that kind of voltage on it. It shorts the SCR transitors (low voltage from the trigger) in the switchbox when the switch is turned off. You also have a "mercury" kill switch that is on the engine that if it is trimmed up to high will not have any spark. There are so many possibile causes. The thing is, you need it to be broken to troubleshoot it correctly.

It also take a special tool called a Peak voltage adapter to test the ignition out on that engine. Just my .02