How do I DVA test stator non-starting motor

Trying to figure out some electrical problems as the motor I got used has never made a spark. How do you do a DVA test on the stator if the motor will not run on its own power? I have plenty of charged marine batteries to turn the motor but I did not know if that would even get close to providing enough rotation to get a good stator DVA voltage reading. Of course I would have the spark plugs pulled before running this to get maximum starter to flywheel powered RPM.

Re: How do I DVA test stator non-starting motor

You need to test it while cranking to see if it's putting out AC voltage, if your battery is good you will see ac while cranking, small motors that are manual start will put out power while pulled over, that's how the system works.

Re: How do I DVA test stator non-starting motor

Would help to know what your working on...

Re: How do I DVA test stator non-starting motor

Hahaha ... your right jeffersondodson. I had posted earlier and forgot to mention it in this one. Its a 1984 Mariner 90hp Inline 6. I talked to the a fine tech at CDI and in as much as I was using other mentioned methods of measuring the stator he said the best way was to disconnect all stator wires BUT engine ground and take measurements from the stator wires Blue to Gnd, Blue/White to Gnd, Red to Gnd and Red/White to Gnd. The measurements should be along the lines of this +/- 20 to 30%:

Blue 5000Ω - 7000Ω Mine read 5300Ω
Blue/White 5000Ω - 7000Ω Mine read BAD 2570.0K OHMS (thats in the Mega Ohm range)
Red 200Ω Mine read 148Ω
Red/White 200Ω Mine read 148Ω

Funny thing, if I moved the flywheel a little, the meter changed a lot for the bad Blue/White wire and the other Blue wire stayed close to the original reading.

My stator appears to be the original one based on wire type, thickness, fading and cracking.

The tech also told me some good info. He said that the Mercury factory recommended replacing the Switch Boxes every 7 years and if both were 10+ years old to replace both at the same time. He also told me to check the individual coils by removing them, carefully pealing back the black protective rubber case and look for cracks on the ferrite core. Boy was I surprised when I saw that three of them had hair line cracks which defeated the idea of what the core does. I will post some of this info in a separate post for others searching for this type of info. I forgot to mention he said to measure the coils secondary to the engine ground for a +/- 1kΩ. I didn't get that far since I feel that 4 out of 6 are bad. Looks like all need replacing plus the stator.

Re: How do I DVA test stator non-starting motor

All of your readings are in ohms (and please tell me where the ohms key is on the keyboard!), ohms should be measured isolated and disconnected from any power source, the DVA will read voltage, what the CDI needs to see in order for the switchbox to work. You cannot use the DVA to take ohms meaurements because of the capacitor and resistor inside the DVA. So you would crank the motor and check the output to the coils, switchbox and triggers. I believe the stator output for the low speed should be around 40 volts @ cranking and about 120 volts for the high speed. If I remember the red is high and blue is low.

Re: How do I DVA test stator non-starting motor

jeffersondodson561 said:

All of your readings are in ohms (and please tell me where the ohms key is on the keyboard!), ohms should be measured isolated and disconnected from any power source, the DVA will read voltage, what the CDI needs to see in order for the switchbox to work. You cannot use the DVA to take ohms meaurements because of the capacitor and resistor inside the DVA. So you would crank the motor and check the output to the coils, switchbox and triggers. I believe the stator output for the low speed should be around 40 volts @ cranking and about 120 volts for the high speed. If I remember the red is high and blue is low.

Click to expand...

Ahh number 937; genius! Ω

Re: How do I DVA test stator non-starting motor

For me (Mac user) its "Option + Z" = Ω

I told the tech that my motor was not running. He said to isolate the stator and do the Ω's test. So I guess replace stator at this point? Then go on to see if the switch boxes are functioning fine (can a switch box be energized if there are no coils hooked up to it?). I have started checking out the ignition coils and found 4 out of 6 back. Tell me what you think of the photos I posted here: http://forums.iboats.com/showthread.php?t=479055&p=3241380#post3241380

I am trying to pass on the help that so many of you out there provide to me. I gratefully appreciate it. I am trying to get a budget boat running on a budget if that is even possible.

I plan on buying the DVA parts tomorrow.