no spark at points

I have a ford 800 that has been converted to a 12 volt system (neg ground) and a one wire alternator My problems started with the carburetor which I rebuilt. Now I don't have any spark at the points, I replaced all the primary and secondary wiring. I've got power to ignition key and from the key to the coil (+) and from the coil (-) (the coil has a resistor inside)to the distributor... but no spark at points. I also replaced points, condenser, and the copper bolt that goes through distributor housing. The coil heats up ?????? Any ideas would be greatly appreciated, Thanks

If the coil heats up you simply have a short some place in the distributor. Good chance the insulator in the side of the distributor is bad. My 841S Ford has had a wire going threw the hole the insulator was once in and has for decades

Are you sure the points are opening?

You should have 12V on the coil terminal going to the points when open, then 0V when they are closed.

+1

The coil is designed to operate with no resistor, neither external nor inside the case. The windings of the coil are designed to operate well with charging voltage while running. Coils operate, when the engine is running, about 50% of the time. This is the amount of time the points are closed, compared to when they are open. Though the on off cycle is at engine speed, the effect is to limit the "on" time. the coil is not intended to stay on. If while you were testing the system, the ignition was on for even 3 or 4 minutes, it will begin to heat up. Engines tend to stop with the points closed because of the compression strokes and unused power strokes positioning the pistons just so. Putting a test light on the distributor side of the coil and cranking the engine with the ignition on should show a flashing of the test light as the points open and close. Assuming the light never flashes, and that the wire from coil to the distributor is in the open and good, the distributor connection through bolt, or the points and or condenser, are shorted to ground. With a plastic knife from fast food, or a piece of plastic cut from a milk jug, placed between the points, see if the battery voltage is now at the coil- If not, My guess is the insulation washers where the pass through bolt is located is ut of place allowing the bolt to touch the housing. Jim

At you using a multimeter to measure voltage and current ? Or relying on the sight of a spark ?
Is there 4.0 amp through the points when they are closed and zero amps when they are open ?

dolly, when you state "I've got power to ignition key and from the key to the coil (+) and from the coil (-) (the coil has a resistor inside)to the distributor...

NOTE With the tractor sitting not running the points are "usually" closed in which case there would be voltage on the coils Input (from ign switch) but there should be zero or near zero volts on its output (to distributor) because closed points takes that to ground

If you ALWAYS have voltage on the coils output (to distributor terminal) as engine is cranked or points are supposed to be closed THE POINTS ARE NOT ACTUALY FULLY CLOSING OR MIS WIRED OR BAD

Check to insure the points are actually opening (to correct gap) and fully closing as dist shaft turns ??????????

Insure the points are correctly wired to the stud inside where on other side the wire runs from the coil

If alls well if you put a test lamp on the coils output to distributor) terminal and turn on ign and crank engine over THE LIGHT SHOULD FLASH ON (when points are open) AND OFF (when points closed) !!!!!!!!!!!!!!!!!

If you now have a full true 12 volt coil there wouldn't be any needed external ballast resistor

If the key is on and points closed engine not running the coil will get fairly hot. When running its not as hot since points are opening and closing

Check if the points are wired correct inside the distributor !!!!!!!!!

Instead of guessing if you work through my Ignition Troubleshooting Procedure it can help find the problem

http://www.ytmag.com/cgi-bin/viewit.cgi?bd=farmall&th=5745

John T
John Ts Ignition troubleshooting

Check the points and make sure they are conducting current from point to point if that makes sense.I have had several sets with a coating on them that you have to file or use fine sandpaper on to get continuity between them.If you have a meter you can check for that across the points.

Something here does not add up.

You first said that you have power to both the (+) and (-) terminals of the coil. Later you say that the coil is getting hot...

IF you have power on both sides of the coil, that would indicate an open circuit. As in points not closing (or conducting) to complete the circuit. If that is the case, the coil should not get hot. No complete circuit, no current flow, therefore nothing to heat up the coil.

If, on the other hand, the coil is getting hot, that says that current is flowing. In this case, it would not be possible to have power on the (-) side of the coil.


Somewhere along the way, you have made a mistake. It just cannot be both ways.

(quoted from post at 12:18:16 09/02/20) Something here does not add up.

You first said that you have power to both the (+) and (-) terminals of the coil. Later you say that the coil is getting hot...

IF you have power on both sides of the coil, that would indicate an open circuit. As in points not closing (or conducting) to complete the circuit. If that is the case, the coil should not get hot. No complete circuit, no current flow, therefore nothing to heat up the coil.

If, on the other hand, the coil is getting hot, that says that current is flowing. In this case, it would not be possible to have power on the (-) side of the coil.


Somewhere along the way, you have made a mistake. It just cannot be both ways.

Click to expand...

ou are one paying attention! Good.