mercury v6 no spark

[nbnewbie]

I need help please. I have a Mercury v6 serial # 5203765 with no spark. I will start from the beginning, but try not to make this too long. Went fishing last week outboard ran great, came in at the end of the day, beached the boat at the ramp and went and got the truck and trailer. When I tried to load the boat the outboard wouldn't start. Loaded the boat with the trolling motor and pulled it up on the parking lot. Opened the engine cover starboard side to see if there was anything obviously wrong, like broken wire or something. Didn't see anything obvious a friend of mine at the ramp at the same time asked what was wrong and I told him it wouldn't start. He said to try to start it and he'd try to see what was wrong I turned the key and it started first crank so i shut it off immediately. I backed it back down the ramp and in the water on the trailer I tried starting it again and again it started first turn let it run for a while shut it off, tried it several more times and no problem. Figured I had flooded it and brought it home. Went to fish a tournament the next day backed it into the water and it wouldn't start definitely no spark. Came home and started troubleshooting. I have now replaced the stator, trigger, switch boxes, rectifier, and eliminated the kill switch, and still no spark either side. I am open to suggestions, but also have a question would someone explain the relationship between the ign switch, kill switch, and ignition. I realize the outboard does not need power to the the ign to run but i also know that as is you have no spark with the ign switch off or the kill switch on is there a way to bypass the ign switch function for testing purposes?

 

[CharlieB]

Re: mercury v6 no spark

Think of these ignitions as a magneto, the stator generates the voltage to operate, the trigger generates a small voltage to trigger the switchbox, which has stored a charge then sends it to the appropriate coil to fire that plug.

Each switchbox has a black wire with a thin yellow strip that is the 'Ground-to-Kill' lead.

The OFF position of the ignition switch grounds this lead to the solid black ground wire, very effectively killing the ignition.

When you have a 'no spark' condition the first test to run is disconnect that black w/yellow from the switchbox(s) and retest for spark. If you now have spark then suspect a ground somewhere in the wiring, often a dying ignition switch.

 

[Faztbullet]

Re: mercury v6 no spark

Disconnect the mercury switch the top of ignition plate...

 

[j_martin]

Re: mercury v6 no spark

Systematic diagnostics is the fastest and least expensive way to a repair.

You could have a pretty well equipped shop with the money you threw into parts with no repair. Odds are it's pretty simple, like others have said. A kill circuit fault is one of the easiest to find with logic guided troubleshooting.

 

[nbnewbie]

Re: mercury v6 no spark

Thank you for the replies. I didn't give up this afternoon and did get it fixed. Learned alot in the process. I have 2 complete outboards for this boat one is a little newer but almost identical so luckily I didn't have to buy any parts when doing my replacements. What I discovered is exactly what your posts point out, that instead of ign switch on supplying a "power on" circuit to the boxes, ign switch off supplies a ground to the boxes at the black/yellow stripe wire. That switch off ground had shorted to constant ground switch off and switch on. Traced the wire, fixed it, and solved the no spark problem. If I ever experience a "no spark" situation again my first test will be as suggested by CharlieB -- When you have a 'no spark' condition the first test to run is disconnect that black w/yellow from the switchbox(s) and retest for spark. If you now have spark then suspect a ground somewhere in the wiring, often a dying ignition switch. -- Thanks again for your time and knowledge in the replies, I really appreciate it.