It's spring and I can't get the Bug going! Battery's charged, points and plugs, polished, fuel bulb cleaned, but I'm not getting any spark from the coil lead. Do I need a new one? I figured if that's not happening, I've got to start there. Any suggestions? Thanks everyone, in advance.
Do I need a new Coil?
- Thread starter 1930Bug
- Start date
J Franklin
Well-known member
To check the coil I set the points open, and with the key on bridge the points with a screwdriver. If the points are not working this will bypass the contacts.
Patrick L.
Well-known member
What is voltage at open point arm ? Should be 6v
What is voltage at closed point arm ? Should be zero. If not, clean them.
What is voltage at closed point arm ? Should be zero. If not, clean them.
eagle
Well-known member
Check voltage on the point side of the coil. With points open, should be battery. Turn engine over by hand crank until points are closed, should now be 0v on point side of coil. If not, points need more cleaning/burnishing. DON'T start replacing parts. You'll just end up introducing problems.
Chuck Sea/Tac
Well-known member
You need low voltage to get high voltage. That’s why you should start with the low voltage primary circuit. If something in the low voltage circuit is grounded/shorted out, then it won’t “charge” the coil for high voltage. Here is a simplified wiring diagram of just the ignition circuit.
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rotorwrench
Well-known member
A multi-meter will allow a lot of checks on electrical components. Set to read Ohms, the coil can be checked between the two terminal posts for a reading very near 1.5-Ohms. If no reading the the coil is open somewhere in the winding and no good. If the reading is much higher, then it is either a 3-Ohm coil or it has damage internally that is causing high resistance. The secondary coil winding can also be checked. Only one of the two small terminals is connected to the secondary and the other end is connected to the tower high tension terminal. The secondary has very high resistance due to the high number of turns in its coil. Resistances vary with manufacturers but they would likely start around 8,000 to 12,000 ohms.
Back in the day, there were test sets for coils that powered them up for a period of time to warm the coil up. There was a breaker set built into the unit to provide a high tension spark during the test. If the test set gave serviceable indications then it was good to go. If a person has no test set then it has to be tested in the vehicle with a home made test rig. Some coils fail after they warm up due to a crack in the wire that grows with heat. This is the reason they warmed them up before testing.
Back in the day, there were test sets for coils that powered them up for a period of time to warm the coil up. There was a breaker set built into the unit to provide a high tension spark during the test. If the test set gave serviceable indications then it was good to go. If a person has no test set then it has to be tested in the vehicle with a home made test rig. Some coils fail after they warm up due to a crack in the wire that grows with heat. This is the reason they warmed them up before testing.
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Bill G
Well-known member
Notice that nobody has suggested to automatically assume that no spark means to replace a part.
Coils don't go bad that often. There are several parts and adjustments in the path of no spark. It could be as simple as a blown fuse. Throwing new parts at solving a problem can be an expensive proposition.
I wholeheartedly agree with getting a volt meter out and following the circuit. Good luck!
Coils don't go bad that often. There are several parts and adjustments in the path of no spark. It could be as simple as a blown fuse. Throwing new parts at solving a problem can be an expensive proposition.
I wholeheartedly agree with getting a volt meter out and following the circuit. Good luck!
slatgrille
Senior Member
I'm having the same issue. I 'fired up' Bessie (my '29 RPU) a few weeks ago, only to have it quit then not start again. Last summer I put in new points, condenser, plugs, cap, rotor, armored cable with new switch, new wires, etc. and had it running around the yard and up-n-down the road last fall before I put it away for the winter.
I thought I may have flooded it, but when checking the points for an arc w/a screwdriver....nothing. I started at the fuse, ignition switch, then ammeter....nothing. Before 'losing my mind', I walked away from it and thought about doing exactly what Bill G just said above. I will put it back together and use my voltmeter to chase the issue once it warms up around here.
I thought I may have flooded it, but when checking the points for an arc w/a screwdriver....nothing. I started at the fuse, ignition switch, then ammeter....nothing. Before 'losing my mind', I walked away from it and thought about doing exactly what Bill G just said above. I will put it back together and use my voltmeter to chase the issue once it warms up around here.
I doubt it is the coil. A component across the point path needs to be checked. It is the condenser. They can and do fail.
rotorwrench
Well-known member
I don't know what companies still manufacture the model A type condenser. A&L was making a good quality unit with modern materials that held up fairly well to the heat. I assume they are still available but less is certain in this day and age.
The modernized plate with late type Ford applicable condenser seems more common than it once was. I used to use the Echlin condensers but they are now owned by Standard Motor Parts. I've had my ups and downs with modern types and have purchased two or three at a time to insure I'd at least get one that would work properly. Many are bad right out of the box. Some will work but get unreliable at low rpm. When I get a good one, I run it till it starts to get flaky then try another one.
Leaving the ignition switch on while points are closed will kill a coil so I always double check to make sure the pop out button is pushed in before I leave the car to set.
The modernized plate with late type Ford applicable condenser seems more common than it once was. I used to use the Echlin condensers but they are now owned by Standard Motor Parts. I've had my ups and downs with modern types and have purchased two or three at a time to insure I'd at least get one that would work properly. Many are bad right out of the box. Some will work but get unreliable at low rpm. When I get a good one, I run it till it starts to get flaky then try another one.
Leaving the ignition switch on while points are closed will kill a coil so I always double check to make sure the pop out button is pushed in before I leave the car to set.
Okay, thanks everyone. I repolished all contacts, trouble light was giving me 6 volts at each point, cranked it over a while and, finally, she fired up and started!! I guess she just needed a stern talking to . . . or perhaps the gas was a bit stale. Anyway, she's running, so thanks for the encouragement and happy motoring!!
Big hammer
Well-known member
Yea! A little work and no parts needed! Now go for a long drive and enjoy!
