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Old 05-18-2013, 10:56 AM   #1
roccaas
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Default Ignition Troubleshooting-What am I missing?

Won't start, will crank over, no spark when grounding the coil wire.

I've followed Les's Troubleshooting guide, and I've got 6.24 volts:

across the battery
at the battery wire to starter
each side of the 30 amp fuse on top of the starter
both poles of the terminal box
both poles of the coil
and at the points arm when the ignition is ON and the points are OPEN with a piece of paper.

I replaced the lower plate and pigtail (modern plate) as the pigtail was on it's last strands at the attachment to the lower plate.

I replaced the coil and coil to distributor wire.

Checked continuity for Zero Ohms on every wire in both harness:

Alternator to terminal box
Starter to terminal box

Switch to both the +Coil and the lower plate of the distributor through the armored cable
Jump wire from terminal box to -Coil
Both wires back to the Ammeter

The upper plate shows 0 Ohms to ground

The rotor is at 4:00 at TDC for Cylinder 1

I've got fuel coming back out of the carb air intake (Tilly) after I try cranking with no Start.

I get the occasional pop after I try cranking for a few seconds, I put this down to the excess fuel and an intermittent pulse from the electrical system.

What should I check/try next?

Thanks
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Old 05-18-2013, 12:30 PM   #2
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Default Re: Ignition Troubleshooting-What am I missing?

Please verify that with points closed, you read zero volts from the + coil lug to ground.
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Old 05-18-2013, 12:41 PM   #3
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Default Re: Ignition Troubleshooting-What am I missing?

If I understand, opening and closing the points with a screw driver produces no spark coil wire to head bolt.

If this the case need to go back through troubleshooting. You are missing some thing. Remove -coil wire, with key on opening and closing the points check continuity -coil wire to ground (points open no continuity---- points closed 0 resistance to ground)

Make these checks and we will go from there.
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Old 05-18-2013, 12:42 PM   #4
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Default Re: Ignition Troubleshooting-What am I missing?

Did you remove a sparkplug and check for spark?
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Old 05-18-2013, 01:05 PM   #5
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Default Re: Ignition Troubleshooting-What am I missing?

make sure the metal jacket covering the wire to the dizzy is not grounding out when it is laying on the head.
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Old 05-18-2013, 01:20 PM   #6
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Default Re: Ignition Troubleshooting-What am I missing?

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Originally Posted by Rock Hornbuckle View Post
Did you remove a sparkplug and check for spark?
No spark, either at plug, or grounded coil wire.
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Old 05-18-2013, 01:37 PM   #7
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Default Re: Ignition Troubleshooting-What am I missing?

Spark comes from an electrical discharge of the condensor when the points open. Have you checked your condensor?
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Old 05-18-2013, 02:13 PM   #8
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Default Re: Ignition Troubleshooting-What am I missing?

This is my generic no spark troubleshooting 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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Old 05-18-2013, 07:38 PM   #9
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Default Re: Ignition Troubleshooting-What am I missing?

Quote:
Originally Posted by roccaas View Post
No spark, either at plug, or grounded coil wire.
When you say grounded, I hope you mean holding the wire 1/4" away from ground. Stop the engine with the points open, key on, then short the points contacts with a screwdriver off-on-off-on, etc. and see if you get a spark each time the points are opened by the screwdriver. If so, then the contact need to be cleaned. If not, check the ground for the distributor frist, and if that's OK, then try changing the condenser.
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Old 05-19-2013, 07:35 AM   #10
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Default Re: Ignition Troubleshooting-What am I missing?

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Originally Posted by Tom Wesenberg View Post
When you say grounded, I hope you mean holding the wire 1/4" away from ground. Stop the engine with the points open, key on, then short the points contacts with a screwdriver off-on-off-on, etc. and see if you get a spark each time the points are opened by the screwdriver. If so, then the contact need to be cleaned. If not, check the ground for the distributor frist, and if that's OK, then try changing the condenser.
I will get back under the hood on Sunday~~~it is amazing how family obligations get in the way of Electrical Gremlin Hunting.

I will replace the Condenser today as I can get it locally. I will also run back down through the suggestions above.

I get no spark when I open the points when the ignition is closed (on). I get no spark from the new coil wire/coil when cranking the starter and grounding the coil wire.

Thinking back, I had a similar problem in 2007 or 2008, and replacing the armored cable was the trick (it came to me at 3 this morning). The cable on the car is the non-pop out, look alike. I cannot get to Smith and Jones for a replacement until Friday. I travel a great deal, but at least I DO go past S'nJ at least once a week!

The wire does have good continuity from the switch-to the spring-loaded head of the cable-to the pigtail, and I'm careful not to screw the cable end too far into the distributor.

How does one effectively test for grounding of the wire-to the armor-to the head?
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Old 05-19-2013, 08:19 AM   #11
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Default Re: Ignition Troubleshooting-What am I missing?

If you have 6 volts at the open points contact, then the primary coil wiring should be fine. It should also drop to 0 volts when the contacts close, and if it doesn't then the contacts need to be cleaned, or the housing needs a better ground.
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Old 05-19-2013, 09:17 AM   #12
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Default Re: Ignition Troubleshooting-What am I missing?

I usually short the open points with a screwdriver with the ignition on and check for spark (both at the screwdriver and between the coil wire and the head). This tells me if the problem is scale on the points.
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Old 05-19-2013, 10:18 AM   #13
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Default Re: Ignition Troubleshooting-What am I missing?

As mentioned in post 6 and 10, it seems that you are still grounding the coil wire. As was mentioned, the coil wire can't be grounded and check for a spark. It needs to be appr 1/4" from a good ground. Maybe I'm misunderstanding what you're saying.
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Old 05-19-2013, 10:26 AM   #14
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Default Re: Ignition Troubleshooting-What am I missing?

Something similar came up the other day that may apply here. Take a short wire with aligator clips on each end. Clamp the aligator clips , one at each wing nut of the terminal box and see if it will crank up. this will bypass the ignition switch. If it cranks and runs, there is probably a problem with the ignition switch. The fact that it sometimes pops tells me that the spark is intermittant and probably a faulty ignition switch. I've hat problems with the low cost switches.
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Old 05-19-2013, 10:41 AM   #15
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Default Re: Ignition Troubleshooting-What am I missing?

Someone can correct me if I am wrong. The spark is produced by the collapsing field in the coil when the points open. The condenser is there to act as a buffer to keep from burning the points up. The car would run with out a condenser but would burn the points. The reason condensers go bad is because they short to ground internally making an easy path for the current to travel ground instead of the points. The condenser is only carrying the battery voltage not the the spark voltage.
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Old 05-19-2013, 11:12 AM   #16
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Default Re: Ignition Troubleshooting-What am I missing?

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Someone can correct me if I am wrong. The spark is produced by the collapsing field in the coil when the points open. The condenser is there to act as a buffer to keep from burning the points up. The car would run with out a condenser but would burn the points. The reason condensers go bad is because they short to ground internally making an easy path for the current to travel ground instead of the points. The condenser is only carrying the battery voltage not the the spark voltage.


You're close.

The condenser is a capacitor that stores a charge then releases it in the opposite polarity, causing an oscillation. It also provides a path to ground for the HV high frequency oscillations (the larger half of the coil).

A capacitor (condenser) can go bad by shorting, becoming leaky (a resistor), or losing an internal connection and becoming an "open circuit".

If your condenser shorts, the car simply won't run. If the condenser becomes leaky, your car runs badly. If the condenser becomes an open, your car will backfire and buck and run so bad, you'd wish you were at home in bed.

What kills capacitors? Heat!
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Old 05-19-2013, 11:48 AM   #17
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Default Re: Ignition Troubleshooting-What am I missing?

Quote:
Originally Posted by Patrick L. View Post
As mentioned in post 6 and 10, it seems that you are still grounding the coil wire. As was mentioned, the coil wire can't be grounded and check for a spark. It needs to be appr 1/4" from a good ground. Maybe I'm misunderstanding what you're saying.
I hold the distributor end of the coil-distributor wire (with insulated linesman's pliers) about 1/4th of an inch from a head bolt that is stripped of paint.

When the car runs well, I get a nice blue snapping spark off of the end of the coil wire. No spark today.
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Old 05-19-2013, 11:48 AM   #18
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Default Re: Ignition Troubleshooting-What am I missing?

I went back and reread the original post. Modern lower plate jumps out at me as a possible problem. When you say modern lower plate, that goes with the modern upper plate with the condenser mounted under the distributor cap. Besides the mnodern condensers causing lots of problems, as P.S. states above, Heat kills capacitors. It gets purty hot under the distributor cap and the condenser gets NO air for cooling. Go back to the original setup with a short proof condenser and your problems will probably be solved.
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Old 05-19-2013, 11:49 AM   #19
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Default Re: Ignition Troubleshooting-What am I missing?

Quote:
Originally Posted by Purdy Swoft View Post
Something similar came up the other day that may apply here. Take a short wire with aligator clips on each end. Clamp the aligator clips , one at each wing nut of the terminal box and see if it will crank up. this will bypass the ignition switch. If it cranks and runs, there is probably a problem with the ignition switch. The fact that it sometimes pops tells me that the spark is intermittant and probably a faulty ignition switch. I've hat problems with the low cost switches.
I did bypass the ignition switch, both with a jumper between the ignition switch screws, and bypassed the ammeter with a jumper between the terminal box screws.

Still no spark. no start.
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Old 05-19-2013, 11:53 AM   #20
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Default Re: Ignition Troubleshooting-What am I missing?

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Originally Posted by midgetracer View Post
I usually short the open points with a screwdriver with the ignition on and check for spark (both at the screwdriver and between the coil wire and the head). This tells me if the problem is scale on the points.

When I retime the distributor I use Marco's instructions to set the cam against the point rubbing block.

Taking out the backlash with the special cam wrench, and the ignition on, the first "twitch" of the cam brings a nice spark. Today, sadly, no spark.
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