Coil failure

K

Kaptain Karl

Member
I was driving my AA the other day and the engine started to sputter and eventually died. I thought it was out of fuel , but have plenty of that. Noticed that the spark was not there. The ignition switcth tested fine and I am getting power to the points but the truck still wont start. Could the coil just die or am I missing something? Turns over with fuel in carb but wont fire. Thanks Karl:confused:
 
was the coil to hot to touch? if so i would suspect the coil, next check or replace condensor
 
Thats the way that My AA once did !!! Modern points and condenser? We see this often. The truck was too heavy for me to get it off of the road and it had to be towed. This is an experience that i'll never forget. That was the day that I changed back to the original set up.It could be the coil but I doubt it.
 
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If you are getting power down to the points then the primary ignition circuit is intact. This includes the coil primary winding, the ignition switch, the pop-out cable, and the wire that connects the upper and lower plates in the distributor. If you think the problem is electrical it could be the secondary windings of the coil. They can short out when the engine is very hot due heat expansion in the secondary wires. Especially a high performance coil. There could also be a short in the top section of the distributor.

However, if you say the engine sputter and died, it sounds more like lack of fuel. An electrical problem causes the engine to stop firing immediately, whereas loss of fuel the engine usually spools down. I would check that the gas cap vent is not plugged.

Tom Endy
 
Kaptain Karl said:
I was driving my AA the other day and the engine started to sputter and eventually died. I thought it was out of fuel , but have plenty of that. Noticed that the spark was not there. The ignition switcth tested fine and I am getting power to the points but the truck still wont start. Could the coil just die or am I missing something? Turns over with fuel in carb but wont fire. Thanks Karl:confused:
Click to expand...

The spark was not where?
At the end of the coil wire when held 1/4" from a head nut?

If so, then I'd first try shorting across the open points with a screwdriver and see if you have a good spark at the end of the coil wire. If not, then I'd try another condenser first, then the coil. I assume you have a solid wire for the coil wire, and not a carbon wire.
 
Won't start check list;

No Spark
Some possibilities are:
1.Blown or defective fuse (use of a fuse is an aftermarket item)
2.Bad connections at ammeter, or ammeter itself (t0 find out put a jumper wire from one post of the terminal box to the other to take the ammeter out of the circuit temporarily)
3.Bad ignition switch and/or cable, or loose cable connection at switch.
4.Loose or broken wires at bottom of coil
5.Loose or broken wires inside terminal box
6.Loose, bare or broken pigtail wire under distributor plate, or wire grounding to plate or distributor body
7.Points not opening, or point arm grounding to cam due to worn rubbing block
8.Worn electrode in underside of distributor cap
9.Loose or broken high tension wire from coil to cap
10.Condenser burned out or grounding (some condensers are too long and can touch the distributor body inside)
11.Weak coil
12.Rotor not turning due to loose cam screw or bad timing gear.


Ok now break out a volt meter (a light bulb can give false readings).
Start at the fuse block, you should have voltage on both sides of the fuse. If you only have voltage on one side, replace the fuse or fuse block.

Now with voltage on both sides of the fuse, move up to the junction box. There should be voltage at both terminals. If voltage is present only on one side the problem is at the ampmeter and you should Jumper the ampmeter for now.
You should have voltage on both sides of the coil. If not,
remove the red wire on the coil and check again. If you now have voltage on both sides, you have a problem further on. If the voltage is still only in one side you have a bad coil.

Open the points with a piece of paper and remove the condenser. Turn the key on and you should have voltage at the points.
Replace the condenser and you should still have voltage.

If voltage is missing, remove the top plate and check for voltage on the bottom plate.

Check is the connector from the ignition switch screwed in to far? Do you have voltage on the wire to the upper plate?

Is this wire shorting to ground or broken?

Remove the paper from the points and see that the points are closed. You should not have 0 volts at the points. If not,
The points are dirty or the distributor is not grounded well to the engine.
 

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Jim Parker Toronto said:
Mike, thanks for that picture, it makes it all look so simple....
Click to expand...

I wish I knew who drew it I would like to give credit. It does make it easier.

Basically you place a piece of paper in the points to open them, turn on the ign and with a test lead on the engine head nut, you should have voltage from the battery and every point along the way to the points. If you do, then you have no opens. Close the points (remove the paper) and you should have now lost voltage at the points. Open the points and you should have a spark from the coil wire to the engine block nut.
 
Here is a simple drawing that may be of help.

Tom Endy
 

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All very good.. I like the wiring diagram on page 92 of the new Brattons catalog. you can take it to the shop and it makes it easy to trace any wires that are in question. If the modern points setup is used, thats where the problem will more than likely be. it could be the points, condenser or a wireless lower plate connection. The wireless lower plate made for the modern points is not a good idea and sooner or later shorts to the housing. The problem that I had was that the points had spark but would spark to the dist. housing but not fire the plugs. Unless the coil was very hot, the coil is not likely the problem.
 
Figured it out. Replaced points and condenser with old school stuff, cleaned the carb and got her started tonite. thanks for all the help
 
Kaptain Karl said:
Figured it out. Replaced points and condenser with old school stuff, cleaned the carb and got her started tonite. thanks for all the help
Click to expand...
coils can fail when hot so i would run her till shes nice and hot before you go adventuring and need another tow... unless you have AAA haha then use it by all means:D

glad to hear you figured it out!
 
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