1995 90 HP Ignition Issues

[akig0711]

I have a Mercury 90 HP outboard ser #0g197967 that will not start. I have plenty of juice from the battery and the starter seems to be spinning fast enough. I have taken the voltage coming out of the red stator adaptor (blue wire) going to the switch box and am getting around 230 Volts on a DVA meter. I'm getting the same out of the stop wire (black/yellow wire). I have 2 sources telling me that my voltage should be at 190V or 180 to 400V. At cranking should it be as high as 230V or does it matter as long as it's above 180? I have tested for switch box output and am getting nothing coming out of the switch box to the coils. My ohms checks show that all primaries are reading at 0 ohms (i'm using an analog meter so the exacts are unknown.) For the secondaries coil 1 is bad at 18000 ohms and both 2 and 3 are slightly low at 750 ohms, i'm willing to say that 2 and 3 are probably good. My questions are,

Are my stator adaptor and stop wire voltage readings to high?
Does it look like I have a bad switch box or could 1 bad coil cause the switch box to not send the voltage?
Is 750 ohms on the coil low enough to call that coil bad?

 

[Texasmark]

My manual covers 94 thru 98. In sections where serial numbers are posted, all posted are above your sn. Therefore what I say here may or may not apply.

"Red stator resistance test, all wires disconnected taken at 65-85 deg F...temp makes a big difference in readings:

plus lead to white green stator, neg to green white: 660-710 Rx1 scale for analog meters.

plus and neg across the yellow stator leads: 0.165-0.181
-----------------------------
Next, troubleshooting procedures:
Note:
If the DVA reading is high, particularly @1000 rpm the adapter is defective.
If the DVA reading is low, the stator, adapter or switch box may be defective.

Test:
Disconnect the blue adapter from the switch box.
Connect the DVA between that wire and gnd.
Crank engine and measure:
Reading 190 to 260v switch box is bad
DVA reading still low iether stator or adapter bad.
Disconnect the green white and white green from the adapter
Measure resistance between those stator leads
If the resistance is as shown above adapter is defective.
If it is incorrect the stator is defective.

Right out of the book man. Best I can do.

Mark

 

[enginepower]

You need to check for 4 volts or better on the trigger wires while cranking. (brown, white and purple each to the white/black) This triggers the SCR inside the switch box to fire the coils.

edit: you can also do a quick ohm test on each (800-1400 ohms) and trigger wires should be open circuit to engine ground.

 

[akig0711]

Thanks for the info, as soon as I can get out and check this i'll let you know if I can get something figured out.

 

[akig0711]

So I shot everything from both posts, I still had 230 volts coming out of the blue wire and everything else checked good. Since that tells me that the switch box is bad I had to look at everything else before I spent that much money. I shot the switch and had like 6 volts coming out of it on all three wires. I was looking over CDI's troubleshooting guide and it says to shoot all three wires to ground and I should have 1+ volts. When I turned the engine the voltage read zero but when I let go of the key the meter went upto 1 volt and then went down to zero. Not sure what that's suppose to mean. After following the whole CDI checklist I found the blue wire was shooting 150 ohms to ground, according the the CDI guide it should be open. I then isolated the stator adaptor from the stator and it was still shorted, so I am going to attempt to get my hands on a stator adaptor and see what that does. I've suspected it bad for awhile.

 

[enginepower]

Well blue to ground should only be open if you have a red stator kit. Do you have OEM stator or CDI? There are 2 different specs for each PLUS there are 3 different setup types you could have. What were your resistance values for the triggers? Have you tried disconnecting the kill wire from the switch box to see if you have spark? And not sure what you are referring to as a stator adapter.

 

[akig0711]

I do have the red stator, not sure if it's OEM or CDI, I wasn't aware that there was an OEM red stator. I don't remember the exact resistance of the trigger but they were within limits (1100-1400) or I would have made a note of it. I have tried to disconnect the kill wire (black/yellow) and same result. I'm getting 230 volts coming out of the switch box on that wire, which is the same voltage I'm getting off of the blue wire. I did get a single freak 160 volts out of coil 2 one time today but never repeated those results. And the stator adaptor was only used on the red stator, It takes the high and low winding voltages and converts them into the single blue wire that goes to the switch box. It has a green/white, white/green, and black input and a single blue output.

 

[akig0711]

Thinking about it I believe I have an OEM stator. The adaptor has a Mercury part number 834949A 2.

 

[akig0711]

I changed out the stator adapter and #1 coil, shot for voltage to coil 1 and it was good, then coil 2 was good, coil 3 was bad. Went back to coil 1 and now its bad. Shot the blue wire for a short and the stator adapter is shorted to ground now. My only assumption is that the stator is frying the adapter. So it looks like i'm going to have to change out the stator, i'm gonna get the black one this time. If my logic seems flawed please let me know.