Export thread

Craftsman 917271121 no spark

#1

M

mikesignal

Hi. I've got no spark on my mower. I've tested the coil - I think I did it right. I got a test light, put one side on positive battery, the other side on the spark plug wire, and it did not light. Does this mean the coil is bad? Basically the spark plug wire is not grounded?


#2

Scrubcadet10

Scrubcadet10

i personally have never heard of testing the coil that way. i've always used a spark tester like this one https://www.amazon.com/Oregon-42-087-Line-Spark-Tester/dp/B0086O8Q8K

So it very well could be the coil is bad, try starting it with the small black coil wire unplugged, not the big plug wire but the small kill wire.


#3

M

mikesignal

Scrubcadet10 said:
i personally have never heard of testing the coil that way. i've always used a spark tester like this one https://www.amazon.com/Oregon-42-087-Line-Spark-Tester/dp/B0086O8Q8K

So it very well could be the coil is bad, try starting it with the small black coil wire unplugged, not the big plug wire but the small kill wire.
Click to expand...

It won't start with the small wire unplugged


#4

B

bertsmobile1

If the module was not buggered before you tested it it definately is now.
The coil has a Hall Effect trigger encapsulated within it.
The trigger is very voltage sensitive.
you test the coil ( secondary winding only ) by connecting an Ohm meter between the spark plug and ground.
The cap itself is replacable but nothing else is
So the usual test is to remove the kill wire
If there is no spark & the air gap is correct then the unit is toast.


#5

M

mikesignal

bertsmobile1 said:
If the module was not buggered before you tested it it definately is now.
The coil has a Hall Effect trigger encapsulated within it.
The trigger is very voltage sensitive.
you test the coil ( secondary winding only ) by connecting an Ohm meter between the spark plug and ground.
The cap itself is replacable but nothing else is
So the usual test is to remove the kill wire
If there is no spark & the air gap is correct then the unit is toast.
Click to expand...

thanks for the replies.

If I'm not mistaken, the test light test that I did would do the same thing as using a meter set to ohms (sort of) -- isn't the spark plug wire grounded back to the battery? So therefore using the test light, one side of the light to battery positive, the other side of the light to the spark plug wire. If the wire has continuity back to the negative lead of the battery the light will illuminate. .. Unless I am completely wrong and the spark plug wire does not go back to battery ground.

Either way, there was no spark at the plug when I took it out, placed it on metal, and hit the starter. So I guess I will replace the coil.


#6

B

bertsmobile1

mikesignal said:
thanks for the replies.

If I'm not mistaken, the test light test that I did would do the same thing as using a meter set to ohms (sort of) -- isn't the spark plug wire grounded back to the battery? So therefore using the test light, one side of the light to battery positive, the other side of the light to the spark plug wire. If the wire has continuity back to the negative lead of the battery the light will illuminate. .. Unless I am completely wrong and the spark plug wire does not go back to battery ground.

Either way, there was no spark at the plug when I took it out, placed it on metal, and hit the starter. So I guess I will replace the coil.
Click to expand...

No.
You have a magneto ignition.
It is not connected to the battery like your car's Kettering ignition system is.
It is a closed loop from the coil to the plug through the engine back to the coil.
It is self energising.


#7

M

mikesignal

bertsmobile1 said:
No.
You have a magneto ignition.
It is not connected to the battery like your car's Kettering ignition system is.
It is a closed loop from the coil to the plug through the engine back to the coil.
It is self energising.
Click to expand...

Ah, ok, thanks for the info.

If I ohm it out, what should it read?


#8

M

mikesignal

I was poking around, and found the back of the ignition switch is loose/wasted. When I move it around I can hear the solenoid on the carburetor engaging and disengaging. Must be killing power to everything. Switch ordered.


Footer Links 1

Top