Ford 9N intermittent spark, won't run

[JRP3]

6 Volt positive ground system, parked it about a month ago, now it will only fire for a second if at all. Put a clamp on timing light on the plug wires and only occasionally get a flash when cranking. Put a test light between the coil and ground, it lights when the ignition is on and flashes when cranking, so I'm assuming the points are working. Volt meter between the coil and battery ground shows voltage fluctuating when cranking between full battery voltage and about 2.5V. Coil is about 3 years old, tractor hasn't seen much use. Sanded the rotor, cap, and points even though they didn't look bad. Haven't tried hot wiring from the battery to the coil yet but I guess that's the next step. Any other ideas?

 

[RickB]

Check the ballast resistor behind the dash.

 

[JRP3]

What readings should I get?

 

[RickB]

Resisted voltage to the coil should be about 4 volts with points closed.

 

[JRP3]

So when I was reading the coil voltage while cranking and it dipped to 2.5V that was too low, or is it not accurate while cranking it?

 

[RickB]

I'd call it low. It should fluctuate between 6 and 4.5 while she points open and close, dependent on voltage drop caused by the starter's current draw.

 

[Roadworthy]

Clean your battery terminals well, as well as the connectors that attach to them. Tighten securely. Follow the ground to the frame and be sure it's clean and tight. Any voltage drop at any of these points is too much voltage drop. If it still won't run check the point gap and the timing. Do you have any moisture or cracks in the distributor cap? Are you sure the rotor makes good contact with the center of the cap? Are you sure your condenser is good? Be sure the points are tightened down securely.

 

[John0829]

Jumper around your key switch, that has always been a weak part of the ignition system.

 

[ROUSTABOUT]

6 Volt positive ground system, parked it about a month ago, now it will only fire for a second if at all. Put a clamp on timing light on the plug wires and only occasionally get a flash when cranking. Put a test light between the coil and ground, it lights when the ignition is on and flashes when cranking, so I'm assuming the points are working. Volt meter between the coil and battery ground shows voltage fluctuating when cranking between full battery voltage and about 2.5V. Coil is about 3 years old, tractor hasn't seen much use. Sanded the rotor, cap, and points even though they didn't look bad. Haven't tried hot wiring from the battery to the coil yet but I guess that's the next step. Any other ideas?

CONDENSER

 

[Chilliwack Murray]

As the previous poster said… Condenser.

Disconnect it and see if you get spark.

 

[ruffdog]

There are some bad import condensers out there too that are bad out of the box.

 

[CalG]

what type of "test light" can be placed between a coil and ground that shows if the points are good?

A dwell meter, sure. but a test light? Doesn't seem right considering a typical point's condenser circuit.

 

[JRP3]

what type of "test light" can be placed between a coil and ground that shows if the points are good?

A dwell meter, sure. but a test light? Doesn't seem right considering a typical point's condenser circuit.

It's a 6-12 volt probe with a point on one end and a cable with an alligator clip on the other and a light in the clear plastic handle. I put the clip on the top post of the coil and put the probe to ground, when the ignition switch is on and the points are open it lights up and when you crank it and they close it turns off. At least that's what assume is happening.

 

[JRP3]

There are some bad import condensers out there too that are bad out of the box.

Are the Tractor Supply ones any good? That's probably the closest source for me, maybe NAPA would have them too.

 

[ruffdog]

My friends 8n would only have spark once in a while and he put new points in. I ended up putting in the old condenser to fix it. Then I read about other Ford owners having the same issue. I didn't research makers to find good/bad sources.

 

[JRP3]

All the reviews on this kit from Tractor supply are 1 star I'll be avoiding that one.
https://www.tractorsupply.com/tsc/product/tisco-tune-up-kit-atk6ffr

 

[Hotpot]

I had a problem similar to yours with my 1974 IH 354 gas and i went round and round with it for about a year. It would start then wouldn't want to start. I don't like throwing money at problems so i tested everything still no luck. I finally replaced the distributor cap ( the old one looked good no cracks or damage and fit well but) some how it was shorting inside because soon as i replaced it never had another problem. The tractor sits for long periods of time now and still starts right up every time.

Dont know if it will help your situation?

 

[ljjhouser]

I would almost say if battery cables are clean and making good contact - replace the cap, rotor, points and condenser. We used to do that with every so many tune-ups to eliminate future problems. Most are low cost parts. Well, been a long time, maybe not now. Best wishes.

 

[square1]

Installed electronic ignition and never regretted it.

 

[JRP3]

Installed electronic ignition and never regretted it.

I'm trying to get it running so I can sell it but otherwise yes I'd probably do that.

Some progress, hot wired the coil and got consistent spark, took off the hot wire and still had consistent spark, so turned on the fuel and it started right up. Died after a few minutes. Hot wired again and got spark, this time no spark when I took off the hot wire. So either I have a bad connection in the ignition circuit, a bad switch, or a bad resistor I guess. At least I was able to get it moved out of my way, when I have more time I'll trace out the problem.