Spark Question

[BigNiner19]

Just a question from a mind eager to learn. Can an Yamaha outboard have "weak" spark? Like say the rectifier going bad, or the pulsor coils, or the stator? Or is it all or nothing?

Is it either spark or no spark? Or is there a point in between where you COULD potentially have weak spark, but still have spark.

The spark I see is very difficult to see and orangish in color it seems. But the motor fires up and runs okay. Sometimes can be very difficult to start. When warmed up, it seems fine.

Cory

[99yam40]

the manual has specs for the lighting coils, charge coils, pulsar coils and the out puts of the CDI. Also ohm readings of the different coils. Just need the proper test equipment to measure and compare to manual specs.

[Tucker]

What the manual doesn't explain is how to test. I think many of us are to humble to ask, that's why we hang around these owner forums. How many volts does that charge coil put out? And I'm going to be holding onto what when cranking the engine?

[99yam40]

The Yamaha service manual for my motor gives the minimum voltage specs at different RPMs and even while just cranking over, even shows where to put the meter leads.
So I am not sure what else you would need.

[rodbolt17]

mostly? the correct meter.

[BigNiner19]

Used a DVA meter to check the pulsor coils, ignition coils, etc. Only thing I was not sure about via the manual is the stator.

Will a stator be the culprit of weak spark?

[jb123]

what motor are you working on ??

[99yam40]

As we are not speaking about any specific motor, my guess is yes there can be weak spark and it is measurable.
But as I said if you measure the charge coil output(spark voltage) , lighting coil output(battery charging voltage), pular coil output, and then the CDI output voltages and compare to the specs in manual you should find the problem if there is one.
Not sure what you call stator as it is not in my manual for my motor

[jb123]

could be as simple as a cap resistor, old wires.....
it runs ok but looking to question the electronics

[BigNiner19]

could be as simple as a cap resistor, old wires.....
it runs ok but looking to question the electronics

It actually did have 3 bad resistor caps on it. I replaced all three.

The motor is a 1989 Yamaha 225 Excel. It sat and didnt get much use over the past couple of years before I bought it. I have had to work a lot of kinks out of it to get it running. IT does seems to run okay when I can get it started. But sometimes it can be hard to start when its cold. Also very smokey at times.

The carbs have been cleaned and rebuilt, fuel pumps changed, and 3 resistor caps replaced.

The Pulsor coils and CDI output voltages all came back within specs. I would have to check the charge coil and lighting coils again as I did not write those down when I had the DVA meter here.

The stator sits on top of the flywheel and has magnets in it and creates spark.

The only reason I'm questioning anything and trying to learn is because I did notice that on prevois outboards the spark was much easier to see. On this one each cylinder is tough to see but there is spark there.

And as mentioned when the motor is cold it is difficult to start when I know it has spark, and I know it has fuel. Once it has been started and warmed it up, it seems to fire up very easily and normal as I've seen it.

Cory

[jb123]

the motor IS 22 yrs old...
feather choke see if it helps while under load
WHO cleaned carbs and when ?
run on hose at night look for any errant spark, may have to pull cover off rear to see coil leads