ford 8n will not fire

[KYErik]

I'm sorry, but I don't understand your symptom of "no spark at points".

Are you looking for a spark between the breaker points when cranking the engine with the distributor cap off?

Or are you looking for a spark from the end of the coil wire going to any ground (engine,frame etc.)?

Your test light results seem perfectly normal.

You won't always see a spark between the points when they open while the engine is cranking.

Crank the engine until the points are open. Leave the ignition on and place the blade of a screwdriver between the points while you hold the high tension coil wire (the end that normally plugs into the center of the distributor) about 1/4 inch from the engine block. When you pull the screwdriver away from the points, do you see a spark between the end of the coil wire and the engine block?

 

[Sutol]

Bypass the key switch. When you prove it is faulty, replace it.

What he said.....common fault

 

[whodat526]

What he said.....common fault

also by pass the resistor and then

 

[whitetiger]

i get fire down to the points after a crank or two i lose spark and will not spark again every thing stays hot just no spark at pionts and points are gaped at 0.15 and like it is supposed to when points are grounded i have no power with test light and when points are open i have power to test light just no spark at points

Its probably just a typo but point gap should be .015 instead of 0.15
Just checking.

 

[lhfarm]

i get fire down to the points after a crank or two i lose spark and will not spark again every thing stays hot just no spark at pionts and points are gaped at 0.15 and like it is supposed to when points are grounded i have no power with test light and when points are open i have power to test light just no spark at points

This does sound like it might be loosing 6V to the coil if you aren't getting spark after a crank or two. Could be a bad switch or a bad connection. I would check the wiring to make sure you don't have a loose connection, or a pinched or cut wire that is failing when the engine is cranking. Did you try bypassing the switch as suggested? That would eliminate one fault point.

If that doesn't solve the problem and the tractor was running prior to your restoration, I would replace the new parts - one at at time - with the original items if you still have them. New parts have been known to be faulty out of the box. You did say you had tried 3 replacements and the odds are they wouldn't all be bad. Still, it has to be something to cause an electrical failure.

 

[J_J]

Here is the diagram of a common ign circuit.

If you connect things correctly, and do the test we have stated, you should have diagnosed and fixed the problem.

To eliminate the switch, jump directly from the Batt, and have the points opened, and then put the screw driver touching the two points and remove them. A spark should occur if parts are good, and connected correctly.

A shorted capacitor will keep the current flowing and not allow spark. You can remove it for testing. It is only used to keep the points from arcing/sparking and pitting.

I believe the ign switch only provides voltage to the coil, and the start button only starts the tractor.


Diagram.

 

[catfishonly]

Thanks all for your help but i think i have found the problem. I tested the breaker plate withe the points open and it was grounded out at the brass screw and the cooper strip the insulation seems to have rotten.But after this fix i will keep you informed if this works.

 

[Soundguy]

points should be set a .020 . make shure the points will open and close if they don't close no fire. also do you have good coil and plug wires? has this tractor ran lately?

points on a front mount set to .015 NOT .02

points on a side mount set to .025


ALL plugs gap at .025 on the 4 cyl fords pre 65..

soundguy

 

[Soundguy]

Thanks all for your help but i think i have found the problem. I tested the breaker plate withe the points open and it was grounded out at the brass screw and the cooper strip the insulation seems to have rotten.But after this fix i will keep you informed if this works.

you can get a new breaker plate.. or use a vylon grommet like a license plate plug / screw setup..

 

[catfishonly]

put in new breaker plate and it did not help.I unhooked the resistor for a few minutes and got fire. i have three resistors that are the same. Can you tell me what value resistor i need. I know i need the resistor inline or it will smoke the coil but is everyone for sure they are not makeing the coil with one inside of it now. I bought the coil from TSC.