1250 no spark

[ironman]

If the wire to the points (neg side of coil) is disconnected, you should see 12 volts on both sides of the coil..

[martyrant]

Originally Posted by ironman

If the wire to the points (neg side of coil) is disconnected, you should see 12 volts on both sides of the coil..

Nothing with the condenser and the points disconnected either. Would that mean the coil is culprit?

I originally thought that but went and brought it over my neighbor's and his ran with mine hooked up and his disconnected so I'm a bit at a loss. I did not bring his up to my house and try it on mine, but figured I would not need to.

[ironman]

Originally Posted by martyrant

On the negative side of the coil there is no voltage with just the key switch on. I thought there should not be 12v there until the engine turns over?

Just want to double check as you specifically bolded the negative side.

Just to clarify....
When everything is working as it should, the points open and close 1/2 the rate of engine rpm
When the points close (make contact), it allows current to flow thru the coil by providing a path to ground, thereby causing spark at the plug.
When the points make contact, you cannot see voltage on the coil because it is essentially grounded.

Points can cause problems like:
No ground is ever given to the coil because the contacts are dirty or pitted or gapped too wide
Ground to the coil is constant because the contacts are pitted and stuck together, or not enough gap.

Another possibility is a bad condenser. The condenser is a capacitor, in circuit, across the point ccintacts meant to keep the voltage constant and prevent arcing.

[martyrant]

Originally Posted by ironman

Another possibility is a bad condenser. The condenser is a capacitor, in circuit, across the point ccintacts meant to keep the voltage constant and prevent arcing.

I did buy and replace the condenser during this troubleshooting and it did not seem to change anything.

I am leaning towards the coil if you are saying with the points and condenser disconnected there should be 12v on the - side.

I'll see if I can snag my neighbors to make sure.

Thank you for the clarification.

[martyrant]

Thank you everyone -- it was the coil it seems. Happy 4th of July!!

I have a few questions since I had tried it on my neighbors and it started and ran -- though I didn't run it for more than a few seconds.

Can a coil go bad slowly? I would run it and it would turn off randomly, I'd go back to it later and it would start back up and run for a while (sometimes the whole time I used it) fine.

[Mike1450]

Yep my 1450 coil did some weird thing over a year. First after starting and running 5 minutes it acted like I was running out of fuel then came back up and was fine for the hour cutting grass. It never died completely I cleaned the fuel system etc... that appeared to make it go away. Then it would miss a little so I changed the plug that appeared to make it go away for sometime (I was not expecting the coil to be bad since it was only 4 years old) Then in the winter it starting back firing. I decided just to change the coil again, never had the issues again for over 2 years now. It was just weird.

[cooperino]

Is that an internal resistor coil? Or non resistor coil? Sorry if this was already asked,

That looks like a Standard Motor "blue streak" external resistor coil....

[ironman]

Originally Posted by martyrant

Thank you everyone -- it was the coil it seems. Happy 4th of July!!

I have a few questions since I had tried it on my neighbors and it started and ran -- though I didn't run it for more than a few seconds.

Can a coil go bad slowly? I would run it and it would turn off randomly, I'd go back to it later and it would start back up and run for a while (sometimes the whole time I used it) fine.

Glad for you, congrats for your perseverance.

Yes, coils can be intermittent as they get old, especially if someone has left the key in the on position for any length of time without the motor running.
When that happens, if the points happen to be closed, excessive current is drawn through the coil and it overheats. It may continue to work, but the insulation between the thin wires inside has been deteriorated and it will never get better, only worse. You can see coils that have been overheated and are the tin casing is all bulged out but they continues to work, so who knows?

One other thing to add about the condenser.....
Make sure the clamp, where it mounts to the coil bracket makes a good clean metal contact, and also, the pig tail wire MUST connect to the NEG coil terminal (with the wire to the points).

Edit to add clarification about Cooperino's questionj about coil resistor....
Most vehicles using coils reduce the current flow thru them with a resistor. In the old days, they mounted a big resistor right there on the coil bracket.
Nowdays they build it internally into the coil. Most of the time the coil is marked as to what it is. You want one with internal resistor.