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View Full Version : Coil Test Fine, NO SPARK @ PLUGS


tattooboy37
09-18-2014, 03:13 PM
Hey everyone, I am having problems getting my '63 w/ 390 started. I got it started a week ago after it had sat for 5 months or so just by adding gas to carb. only took a couple cranks and it ran fine. Now I cant get spark to the plugs. It has an electric ignition and has always worked fine. I tested the coil and got what seemed to be ok readings for primary 1.6 ohms and secondary 10.7 I also replaced the condenser not too long ago. It seemed fine too when I put my multimeter on each end the reading steadily declined. I also tested the lead from coil to distributor. It had a resistance of 4.72 by itself and was reading 15.35 attached to coil/unplugged from dist. If I subtract the 4.72 from 15.35 you get 10.63 which is really close to 10.7 (reading of 2ndary coil). I have a spark plug tester light inserted between plug wire and plug and am getting nothing. I tried the old way too by pulling lead from coil to dist. and tried cranking it over and got no arc/spark there either. this has me confused as why reading seem ok but no spark when I hold it close to the cylinder head and crank engine. Does the reading of 4.72 seem high for just the wire itself?

Is something fried or going on in distributor cap. I don't know terminology for inside the dist. cap but there is a small nub in the center below where the coil wire comes in, it appears a bit dirty, but overall seems fine. Also the rotor has a metal tab mounted on top to contact that nub which also seems fine (only a small black dot from contact point).

Any ideas on what or how I can check dist. cap because everything leading to that point seems fine to me, but of course I could be overlooking something simple like the high tension lead. Shop manual says if the spark is good at high tension lead then the problem is probably in the cap or rotor. So why do I get an ok reading on the meter for the lead wire but no spark when cranking.

Manual also says if there is no spark at high tension lead than problem is most likely in the primary circuit (not sure what they are referring to) , bad lead (seemed to test ok) or coil (seemed to test ok). So what is the PRIMARY CIRCUIT?

Thanks in advance and sorry for such a long post

jopizz
09-18-2014, 05:20 PM
In order for your coil to put out voltage it must get 12V from the solenoid when the engine is cranked. There's nothing in your post that showed that you did any voltage tests in addition to the ohms tests.

John

Yadkin
09-18-2014, 05:40 PM
Coil + gets 12v from the starter solenoid when cranking then 5v from ignition circuit resistor wire when running. Coil - is turned on and off by the distributor points or electronics. Install a jumper wire from the battery positive to the coil + to test that circuit.

tattooboy37
09-18-2014, 10:54 PM
Coil + gets 12v from the starter solenoid when cranking then 5v from ignition circuit resistor wire when running. Coil - is turned on and off by the distributor points or electronics. Install a jumper wire from the battery positive to the coil + to test that circuit.

Thanks for the help. I just want to make sure I understand correctly. I need to hook up a jumper wire and then crank engine or take a reading somehow? Obviously if I crank it and it sparks its a bad solenoid?. Is this just by-passing the solenoid?

How do I do voltage test as recommended by jopizz or is that being done by by-passing solenoid?

thanks again guys

jopizz
09-18-2014, 11:14 PM
How do I do voltage test as recommended by jopizz or is that being done by by-passing solenoid?

thanks again guys

Put a voltmeter on the + terminal of the coil. Crank the engine. If you get 12V then the solenoid is good. If not then the solenoid is bad or the wire is bad. Putting a jumper from the solenoid to the coil and seeing if you get spark when you crank it will accomplish the same thing.

John

tattooboy37
09-18-2014, 11:30 PM
Thanks again guys. I just went out to do a solenoid check that I watched online. he said to check by putting the meters ground to top of solenoid and other lead to the starter side post of solenoid and crank engine. I have a bump starter so I hooked it up and when I had the meter attached it started right up on the first try. Did the meter somehow help to make a connection or was it random?

Tried to turn over a second time w/ the key and it didn't start.
Did test recommended below by jopizz. I grounded meter to engine block and put + lead to + side of coil. cranked motor and it started again.
Tried it a third time w/ just the bump starter and no meter attached and it wouldn't start again.

I'm starting to think maybe something must not be grounded correctly. if the starter was bad it wouldn't crank at all right? It seems each time it does start I can hear the distinctive sound the starter makes as it disengages. all of the other times the fan/belts all turn when cranked but not that noise. just throwing everything out there so you guys have better understanding.

jopizz
09-18-2014, 11:52 PM
Hooking the meter up the way you did would have no effect on sending 12V to the coil. There are two parts to the solenoid. The first part sends 12V to the starter(large post), the second part sends 12V to the coil(small post). Since your car always cranked the first part of the solenoid was always good. It was probably just random that it fired. Solenoids are known to be flaky at times.

You could certainly have a ground problem. There should be a ground strap from the engine to the firewall. It's normally bolted to the rear of the passenger side head. If that's not in place or not tightened down it would cause a number of electrical problems.

John

tattooboy37
09-19-2014, 12:09 AM
Hooking the meter up the way you did would have no effect on sending 12V to the coil. There are two parts to the solenoid. The first part sends 12V to the starter(large post), the second part sends 12V to the coil(small post). Since your car always cranked the first part of the solenoid was always good. It was probably just random that it fired. Solenoids are known to be flaky at times.

John

I guess I'll just replace the solenoid since they are cheap enough. Then I'll know for sure if that's it. Thanks for your help John

jopizz
09-19-2014, 12:12 AM
I edited my post after you mentioned a possible ground problem. I would check that your ground strap is connected and tight.

John

simplyconnected
09-19-2014, 02:15 PM
...So what is the PRIMARY CIRCUIT?...The ignition coil is divided into two parts, as are all transformers. The low voltage side is the primary side and the high tension side is the secondary side.

Grounds are equally important in every circuit because one wire will not complete a circuit. Make sure your points have a solid ground wire connected to the pivot plate it is bolted to. If the points cannot complete the path to ground you will get no spark. Your Coil is grounded by the case. If it is rusty, clean it with a wire brush. With the points open, test your condenser to make sure it is not shorted.

The condenser should show ~.02uf if you pull it out. It is an essential part, creating a 'tank circuit' with the Coil. A weak orange-colored spark can be caused by a bad condenser, weak Coil, bad ballast resistor (or resistance wire from the Key Switch, too low voltage (possibly from a bad ballast (resistance) wire) or bad plug wires.

The wire connected between your Coil (-) negative post and the distributor Points should show NO resistance, it should be very flexible and the insulation must prevent a ground.

The Coil (+) post should have two wires on it. One comes from the resistor wire from the Key Switch, and the other goes directly to the Starter Solenoid I(gnition) post.

Multimeters are good but they give false readings because they draw NO LOAD. Use a test light. Either make one from a 12-volt device (dashboard lamp, 1156 bulb, etc.) or buy one that is not neon.

With the Key Switch on and one end of your test light on solid ground, you should find some power at the Coil (+) terminal, and the same power at your Starter Solenoid (I) terminal wire.

Do this test: Put a spare spark plug wire with a spark plug on the end, into your coil tower and lay the plug on ground. Make sure your points are open and keep the cap off to the side.

Now for the test... turn your key to 'ignition' and ground the Coil (-) neg side with a separate 'test' grounding wire. Every time you pull the wire OFF, your spark plug should show a pretty blue spark. If so, ground at the points and pull the wire off. If you have spark again, trash the test wire and short circuit the points contacts with a screwdriver. This will test for a good ground at the distributor. Again, when you pull the screwdriver away, you should get spark.

If you never get a spark but have voltage at the Coil (+) post, your Coil is bad. - Dave

tattooboy37
09-19-2014, 08:39 PM
Put a voltmeter on the + terminal of the coil. Crank the engine. If you get 12V then the solenoid is good. If not then the solenoid is bad or the wire is bad. Putting a jumper from the solenoid to the coil and seeing if you get spark when you crank it will accomplish the same thing.

John

Ok so I tried testing again, putting meter to + terminal on coil and cranked engine using my remote starter. I only got about 9 volts. car did not start.
Did second test by putting jumper cable from solenoid (same place remote started clips to/ where + bat. cable connects) to + side of coil. Started on first try w/ remote starter.

I let it run for a bit and pulled jumper cable from solenoid and it died right away.

So it appears the solenoid must be bad right? Problem is, I bought a new solenoid this morning and hooked it up and got no spark. Maybe a bad wire somewhere?

tattooboy37
09-19-2014, 09:00 PM
The ignition coil is divided into two parts, as are all transformers. The low voltage side is the primary side and the high tension side is the secondary side.

Grounds are equally important in every circuit because one wire will not complete a circuit. Make sure your points have a solid ground wire connected to the pivot plate it is bolted to. If the points cannot complete the path to ground you will get no spark. Your Coil is grounded by the case. If it is rusty, clean it with a wire brush. With the points open, test your condenser to make sure it is not shorted.

The condenser should show ~.02uf if you pull it out. It is an essential part, creating a 'tank circuit' with the Coil. A weak orange-colored spark can be caused by a bad condenser, weak Coil, bad ballast resistor (or resistance wire from the Key Switch, too low voltage (possibly from a bad ballast (resistance) wire) or bad plug wires.

The wire connected between your Coil (-) negative post and the distributor Points should show NO resistance, it should be very flexible and the insulation must prevent a ground.

The Coil (+) post should have two wires on it. One comes from the resistor wire from the Key Switch, and the other goes directly to the Starter Solenoid I(gnition) post.

Multimeters are good but they give false readings because they draw NO LOAD. Use a test light. Either make one from a 12-volt device (dashboard lamp, 1156 bulb, etc.) or buy one that is not neon.

With the Key Switch on and one end of your test light on solid ground, you should find some power at the Coil (+) terminal, and the same power at your Starter Solenoid (I) terminal wire.

Do this test: Put a spare spark plug wire with a spark plug on the end, into your coil tower and lay the plug on ground. Make sure your points are open and keep the cap off to the side.

Now for the test... turn your key to 'ignition' and ground the Coil (-) neg side with a separate 'test' grounding wire. Every time you pull the wire OFF, your spark plug should show a pretty blue spark. If so, ground at the points and pull the wire off. If you have spark again, trash the test wire and short circuit the points contacts with a screwdriver. This will test for a good ground at the distributor. Again, when you pull the screwdriver away, you should get spark.

If you never get a spark but have voltage at the Coil (+) post, your Coil is bad. - Dave

Hey Dave thanks for some more ideas and info. on how things work. It makes much more sense today after reading and looking at some wiring diagrams. I tried some of the tests and was confused on how to do others or if I can do them because mine is equipped w/ electric ignition system.

My coil has 2 red wired to the + terminal. As you stated one is red from firewall, which goes to ignition. the other red goes to distributor. Then there is a brown from distributor to engine/mounting bracket of coil (ground I assume) and a green from dist. to the - side of coil.

This being said it appears all the wires are in good condition and seem to be tight inside the distributor. Also there is no condenser in my distributor. the one I thought was my condenser is actually mounted near the alternator regulator and I believe its for the radio.

I did the test w/ a light you mention and got the same type of light from both the + coil terminal and the starter solenoid (I) terminal.

I didn't do the final test because I don't have an extra set of plug wires or have points like you were talking about.
Please see the results I got from jumping from solenoid to coil in my previous post and let me know what you think. I'm still confused but at least I got a consistent result.

thanks again for your help, Scott

jopizz
09-19-2014, 10:38 PM
When you are using the remote starter is the ignition key in the ON position. If not when you remove the jumper from the solenoid to the coil you no longer have voltage to the coil.

John

tattooboy37
09-19-2014, 11:24 PM
When you are using the remote starter is the ignition key in the ON position. If not when you remove the jumper from the solenoid to the coil you no longer have voltage to the coil.

John

Oooops! I may have had the key off the last time but I'm used to the remote starter normally not working if the key is off. must be because of the direct jump from solenoid to +coil.

This time WITH the key on it started w/ the same jumper cable set up as before. It didn't die this time either when I pulled the cable from solenoid. This leads me to believe that the red lead from the key ignition must be good because that's the only way power is coming in to the coil that I can see. The schematics say Red/Grn (mine is just red now) is connected w/ brown from Solenoid (I) post. these go thru firewall and become the pink resistor wire to the key ignition.
So where is the bad connection? Could it be the brown wire from the solenoid that joins the red wire that's bad? or is that (I) post no good on the solenoid. I tried a new solenoid this morning and I didn't get anything different.

As fun as this is, its also a bit irritating, but I guess anything worth learning isn't always easy.

Ideas?

jopizz
09-19-2014, 11:35 PM
Your bad connection has to be from the solenoid (brown wire) to the coil. This wire supplies 12V when the engine is cranked. Once it starts and the key is released the pink resistance wire takes over. Remove the brown wire from the solenoid and connect a jumper wire from the solenoid I post to the coil +. This will tell you for sure if it's bad.

John

tattooboy37
09-20-2014, 12:43 AM
Thanks again John.
You described what I was thinking, I just wasn't sure of the way to say it correctly or how the check it. I will pull the brown wire and go directly from (I) to +coil and hopefully that's it. Gotta do it in the morning. Time to relax so I dont screw nothing up. I sure hope this works.
Why isn't the wire like that all the time? does it send full 12v indstead of the lower amount thru the resistor wire. maybe less abusive on coils? I guess only the starter needs the full 12v

jopizz
09-20-2014, 12:27 PM
Since your car was converted to electronic ignition I'm wondering if anything was done with the resistance wire. Some conversions require that you remove it and go straight 12V from the ignition switch. Since your coil wire is red and not red/green obviously some modifications were made. That may account for the brown wire not working. If that turns out to be your problem I would trace the red coil wire back to the firewall and see what's going on.

John

simplyconnected
09-20-2014, 03:22 PM
At the expense of sounding 'forward' I need to cut to the chase. I don't believe in 'throwing parts' at a problem because if you do, you will end up with a basket of good parts that you cannot use or return. I also believe in using sound troubleshooting practices to prove parts to be good or bad.

My schematics and parts books for a '63 Thunderbird shows it came with points and a condenser, although you did say yours was an 'electric ignition'. They all are electric.

"Electronic" spark is another story. I see that John has touched on what has possibly happened before I gathered all my pictures, etc. I also believe that someone has converted your ignition to another system. I'm going to stick my neck out and suggest it is a Ford Durasprark, but it could be another type. Without actually seeing it, I can't tell.
http://squarebirds.org/Electrical/Duraspark/DurasparkII.jpg

This is a typical Duraspark conversion.
One Ford 'convention' you need to know is this: If a wire shows two colors, like blue/red, the wire may be blue and the END will be red. Or, the wire may be blue with a red trace. You may see actual pictures on this site where this holds true.

Electronic components need full voltage that your battery does not have when the starter motor is laboring. By contrast, points use an extra wire is on the starter relay, to bypass the resistance wire from the Key Sw. By far, the Starter Motor draws more power than all other electrical draw combined. You can see the battery voltage drop when your headlights are on during a start.

The Duraspark system shows a ground wire going to the distributor, as you explained. It also needs full +12 volts to run the electronics. This conversion picture shows the pink wire is totally out of the circuit, and replaced with a solid copper conductor. If that is true, there is no need for the 'bypass' wire on your Starter Solenoid. - Dave

simplyconnected
09-20-2014, 03:46 PM
If you have no Ignition Module, then you don't have a Duraspark system.

A more modern and widely accepted system is the Pertronix II electronic ignition. It has a red and black wire. Red goes to full voltage with the key on. and black goes to the coil (-) post.

Look at your coil. If it is 'stock', it will need the resistance wire. If it is a Pertronix 'Flame Thrower' it needs full voltage. - Dave

tattooboy37
09-20-2014, 05:14 PM
If you have no Ignition Module, then you don't have a Duraspark system.

A more modern and widely accepted system is the Pertronix II electronic ignition. It has a red and black wire. Red goes to full voltage with the key on. and black goes to the coil (-) post.

Look at your coil. If it is 'stock', it will need the resistance wire. If it is a Pertronix 'Flame Thrower' it needs full voltage. - Dave

It has a Mallory system installed. It was put in by a 30 yr Ford Master Tech over 15 yrs ago and hasn't had a problem. Sorry I didn't clarify.
Seems like I may have fixed a bug this morning. I was checking all the wire colors to the key/ignition and afterward tried to start it and it fired over. Not sure what to think. All my tests could be worthless if its something w/ a wire that's loose or getting old.
I will see if I can get any consistency w/ test starts today and post later.
I did replace my old coil not too long back as well. Its made by Accel. Could it be that its not compatible w/ the ignition system? Seems odd its worked for the last few months w/ same wires hooked up as before
Thanks

Yadkin
09-21-2014, 12:10 AM
The Pertronix coil can be used with the resistor wire. Constant 12v is recommended but not required.