No Spark

CMorris · May 2, 2009

Working on a '50 8N side mount distr. Tractor started in early april and ran well for the day. I removed the distributor assembly to fix the bolt that secures the unit. Put everything back together. Since then have not been able to start. Replaced wiring harness, ignition, terminal block, coil, entire distributor unit. Don't seem to be getting spark anywhere. Help

Bob · May 2, 2009

Ignition on..

Using a test light, check for power at the ignition switch side primary terminal of the coil.

Got power that far?

If not, check the ignition switch and wiring.

Then, move the test light to the distributor side primary coil terminal.

Power?

No power?

If the engine has stopped with the points open, there should be power.

If the engine has stopped with the points closed, there should be no power.

What does the test light do when you crank the engine?

It should flash as the points are opening and closing.

Make these simple tests, and report back and someone will tell you what to do next!

waltdavies · May 2, 2009

Start at the battery connection and trace the wire with a test light from each connection to the next. You should have power all the way to the open points Close point you should show no connect as it is shorted to the frame.
If all is Ok then use a screw drive with a plastic handle to gently open and close the points with the coil wire held close to the block it should show a good blue spark about 3/8 in long. If all Ok the check your cap and all of the plug wires and plugs. If all is Ok turn the fuel on.
Walt

CMorris · May 2, 2009

Checked with the ignition on and it show current going to the main post on the coil. I do not have a test light but I do have a voltage testing unit. When i do the same for the main terminal on the side of the distributor i get nothing. Even when i crank the engine i still get nothing.

CMorris · May 2, 2009

Picked up a 6-12V light and tested the main post on the coil and i get light. I did notice that the coil is very hot. Any concern? When i check the rest of the connections with the light i get nothing. I pulled off the wire from the top of the coil to the top of the distributor and hve no power here either.

CMorris · May 2, 2009

Bob:

Picked up a 6-12V light. On the switch side of the coil i get power on the distributor side i get nothing.Although when i pull off the wire that connects to the side of the distributor then i get power to both posts on the coil.????

rvirgil_KS · May 2, 2009

Zero voltage reading on distributor side of coil until wire is disconnected. No flashing light at distributor side of coil with engine cranking.

This inidicates a short to ground in the distributor. Could be points not opening, condenser shorted, connecting wire shorted, feedthrough on side of distributor shorted

This would cause continuous current when switch is on and would eventually cause coil to get warm.

Here's a link to a chart that may help.

Bob
Ignition Circuit Test Voltages

waltdavies · May 2, 2009

Coil bad
Walt

CMorris · May 2, 2009

Bob:

Being that this is an out of the box distributor unit, I was not looking closely at it. After your comment i did tighten the condenser and straightend out the main post through the side of the distributor. Now I am getting the light to come on at all three contact points when the ignition is on including the two posts on the coil and the side of the distributor. Now my battery is dead and I will have to wait until I charge her up to test her out. I really appreciate your help.Have a good night.

No Spark

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