ConcoursMustang Forums
Restoring - General discussions that span across many different groups of years and models => Misc Items => Topic started by: Captain Kent on March 21, 2020, 06:31:34 PM
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I am having trouble with my 67 coupe, 6cyl 200ci. Starts but won't run. This is what I have done.
Starter turns over but engine won't run
jumped across directly from the battery to the coil, car runs. (guessing then that the coil is good)
Checked the short wiring under the hood from connector to coil, its good.
Voltage from ign to coil is low .76 volts.
What voltage should I see at the coil?
I think the resistance is bad, is that just a wire or is the resister inside the plug to the ignition? Please see attached photo.
Kent
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The resistor is a long wire taped into the under dash harness.
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The resistor is a long wire taped into the under dash harness.
I am sure that this is my problem. How can this wire go bad and how do I fix?
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The voltage should be around 12 V when starting, 9 V while running.
The resistance wire in in a harness that goes from the ignition switch to the connector on the firewall inside the car. It is called a resistance wire, is pink in color, kind of "lumpy" and is taped in place (so you can't get to it easy). Replacements are available. It can be got to while in the car, but you got to remove a lot of stuff in the way.
Jim
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he can disconnect at the ignition switch & disconnect the firewall connector under the hood then do his voltage resistance test.
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Is this a tach dash car? If so, it may be that the tach is disconnected at the dash. The pink resistor wire is the output of the tach and goes to the firewall plug. Basically, the ignition switch routes the signal through the tach to the coil, but has a pickup from the starter solenoid when cranking the engine.
If it is a tach dash car, jumper the leads on the plug on the underdash harness side and try again. It should work now. If it was plugged into the tach, then the tach may be bad.
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If for non tech application as stated it is in the under dash wire harness 14401, from the ignition switch connector (pink wire 16A) to the connector high up under the dash (if I recall correctly) that mates to the 14290 wire harness. At the 14290 harness is where the pink resistor wire ends, and wire 262 (brown) carries the circuit to the starter relay.
Replacing this is not a simple task.
I recommend pulling the connector off the ignition switch so you can get clean access to the pink wire. Disconnect the battery. Pull the brown wire off the starter relay. Now with some spare wire (almost any will do), extend either end of the circuit through the door to the opposing end. Then with a meter measure the resistance. The ones I have here are reading 1.6 ohms. I have a 68 harness cut up now and you can have the resistor wire, but again this job is pretty big. I’ll attach some pics in an hour or two
Randy please correct me if I’m wrong
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I just noticed this is in the 69-70 area not 67-68, should be moved
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Here is the ignition, starting and charging diagram. The one in the shop manual is not as good.
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Here are some pictures from a 68 harness. I think that there is a difference in the ignition switch connector. Not sure about the other end connector.
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If for non tech application as stated it is in the under dash wire harness 14401, from the ignition switch connector (pink wire 16A) to the connector high up under the dash (if I recall correctly) that mates to the 14290 wire harness. At the 14290 harness is where the pink resistor wire ends, and wire 262 (brown) carries the circuit to the starter relay.
Replacing this is not a simple task.
I recommend pulling the connector off the ignition switch so you can get clean access to the pink wire. Disconnect the battery. Pull the brown wire off the starter relay. Now with some spare wire (almost any will do), extend either end of the circuit through the door to the opposing end. Then with a meter measure the resistance. The ones I have here are reading 1.6 ohms. I have a 68 harness cut up now and you can have the resistor wire, but again this job is pretty big. I’ll attach some pics in an hour or two
Randy please correct me if I’m wrong
No, you are correct. In overhauling 700+ underdash harnesses and seeing another 300 or so, I have only encountered one burned pink resistor wire. It is a very rare thing indeed.
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Didn't think you could get a tachometer with a 6 cylinder.
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The wiring harness is the same regardless of engine cylinder count or size so it can be unplugged.
I would start by measuring voltage at the I terminal on the starter solenoid. Should be 12 volts with the key in "START" position.
Didn't think you could get a tachometer with a 6 cylinder.
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Didn't think you could get a tachometer with a 6 cylinder.
I looked in my Ford sales information and I found no notes excluding 6 cylinders from the Tach dash option. I have never see one in a 67 68 six though. I have see a rally pack in a 1966 6 cylinder coupe.
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Special equipment:
- A three foot 16awg jumper wire with alligator clips.
- A remote starter.
Procedure:
- Hook up the remote starter per manufacturer's instructions. That should be one clip to the positive terminal of the battery, the other to the right hand small terminal of the solenoid, the start terminal.
- Hook up one clip of the jumper to the positive terminal of the battery (it's getting crowded), the other to the "BATT" terminal of the coil.
- with key off, press the start button on the remote, give the carburetor some gas.
Car should start. You have eliminated all wiring for the normal running of the car.
And the results are:
Jim
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The OP did this and said it runs with a jumper from battery to coil. ;)
TOB
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The OP did this and said it runs with a jumper from battery to coil. ;)
TOB
Then why all the extraneous posts?
Jim
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The wiring harness is the same regardless of engine cylinder count or size so it can be unplugged.
I would start by measuring voltage at the I terminal on the starter solenoid. Should be 12 volts with the key in "START" position.
But the harnesses are not the same with respect to tach and non-tach cars in either the main or dash harness (for 67). Even the engine compartment main harness is different.
The red wire power isn't even sourced from the same place on the two harnesses.
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But the harnesses are not the same with respect to tach and non-tach cars in either the main or dash harness (for 67). Even the engine compartment main harness is different.
The red wire power isn't even sourced from the same place on the two harnesses.
I believe we are talking about the engine gauge feed harness, not the underdash, headlight, or alternator harness.
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I'm not sure what we are talking about anymore!
Back to cataloging KH calipers...
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I would still start by measuring voltage at the “I “ terminal on the starter solenoid with the key turned to the “Start”position. Doing that will verify lots of things and takes a few seconds.
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Wow guys you are great. A lot to work with, it is kind of what I thought was going on but didn't have all this information to help. I have to travel in the next couple of days and will tackle this when I get home. I will report back. Really weird deal.
Any idea what caused this? Brand new wiring harness and restoration less than 800 miles and less than a year.
Kent
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You may find it was just a defective ignition switch.
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I did replace the ignition switch, that wasn't it. And remember I jumped from the battery to the coil and the car ran. I really think that the resistance wire is allowing the voltage to drop too low after the starter disengages.
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Here is a schematic I put together that might help. Note that there are three diagrams, representing Off, Cranking, and Running modes.
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Since you can crank and start, but the engine won't stay running, take a look at diagram 3 from the attachment on the previous post, representing when the ignition switch is in the run position.
The steps I recommend are:
Test 1: (easy) measure the voltage from the red-green wire at the coil, with reference to ground, while it is still connected to the coil.
1a. Measure voltage when cranking and report back here. I assume that this is about 12V since you said in the original post that the engine will start with no hesitation.
1b. Measure voltage right after cranking, with key in run, and report back here. I assume that this is near zero since you mentioned 0.76V, but your description of "ign to coil" is not perfectly clear to me.
Note that the following tests would be my recommendation if the running voltage at the coil is near zero.
Test 2: (easy) put the ignition switch in the run (not crank) position, then measure voltage on the brown wire at the starter relay. You can pull the wire from the relay, it does not need to be connected to anything. Reference is ground.
2a. If you have a nominal 12V, then your ignition switch and resistor wire are good. Go to test 4.
2b. If you have no or very low voltage, go to test 3.
Test 3. (intermediate) pull the ignition switch out and temporarily jump from the yellow (battery) terminal to the pink resistor wire. Then measure voltage (reference to ground) on the brown wire at the starter relay. This will bypass the ignition switch contact in an attempt to prove out the resistor wire.
3a. If you have voltage at the brown starter relay wire, then your ignition switch is suspect but pink resistor wire and wiring in general is ok. Replace your ignition switch.
3b. If you have nothing at the brown starter relay wire then you have a problem in the wiring - could be the resistor wire or a connector issue. Go to test 4.
Test 4. With ignition switch in the off position, temporarily jumper battery voltage to the red-green wire of the ignition coil, with the wire pulled from the coil terminal. Measure voltage on the brown wire at the starter relay with reference to ground.
4a. If you have voltage at the brown starter relay wire, wires 16, 16B, and 262 are connected. Keep in mind that this test is with no load, and therefore could show a false positive. Go to test 5.
4b. (difficult) If you have no or low voltage, there is a problem with the wiring or connectors shown on the diagram. Check the 14289 to 14290 harness connector first, which if I recall is in the engine compartment. If that is ok, you will need to get up under the dash and check out the 14401 to 14290 connection point.
Test 5. At this point the ignition switch and resistor wire are good, and the wiring is connected and intact. However, there might be a significant voltage drop across a connection or bad area of a wire while the circuit is loaded, when the engine is running and current is flowing to the coil. What I do in a situation like this is to get a small needle and use it to probe through the wires at various points in the circuit along the way in an attempt to uncover where the voltage drop is occuring. In this particular case I would probably start at the red-green wire ahead of the connector at the coil. Note that these are all measuring voltage with reference to ground, with the key in run. Also note that as you probe along the way, as soon as you find some significant voltage, let's say over 9V for discussion purposes, you have isolated the problem between there and the previous measured point. If that first probed voltage is low, then go to the 14289 to 14290 connector, and measure the red-green wire on the 14289 side, followed by the 14290 side. If those are low, move up to the 14290 to 14401 connector under the dash.
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I had a similar problem with Midlife (66 GT A code) when I first got it. It would crank and catch just fine, but as soon as I let off of the crank key, the engine would die. I traced the problem to a bad connection at the starter motor: the threads were worn away and the nut holding the starter cable was very loose. The bad connection would lower the voltage so much that there wasn't enough going to the coil via the ignition switch and the car would die. I had to replace the starter.
The poster says he gets 0.7V or so in the RUN position at the coil, so there's obviously some high resistance somewhere along the line. That voltage could be stray voltage, and the actual voltage under load is zero---possibly.
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Since you can crank and start, but the engine won't stay running, take a look at diagram 3 from the attachment on the previous post, representing when the ignition switch is in the run position.
The steps I recommend are:
Test 1: (easy) measure the voltage from the red-green wire at the coil, with reference to ground, while it is still connected to the coil.
1a. Measure voltage when cranking and report back here. I assume that this is about 12V since you said in the original post that the engine will start with no hesitation.
1b. Measure voltage right after cranking, with key in run, and report back here. I assume that this is near zero since you mentioned 0.76V, but your description of "ign to coil" is not perfectly clear to me.
Note that the following tests would be my recommendation if the running voltage at the coil is near zero.
Test 2: (easy) put the ignition switch in the run (not crank) position, then measure voltage on the brown wire at the starter relay. You can pull the wire from the relay, it does not need to be connected to anything. Reference is ground.
2a. If you have a nominal 12V, then your ignition switch and resistor wire are good. Go to test 4.
2b. If you have no or very low voltage, go to test 3.
Test 3. (intermediate) pull the ignition switch out and temporarily jump from the yellow (battery) terminal to the pink resistor wire. Then measure voltage (reference to ground) on the brown wire at the starter relay. This will bypass the ignition switch contact in an attempt to prove out the resistor wire.
3a. If you have voltage at the brown starter relay wire, then your ignition switch is suspect but pink resistor wire and wiring in general is ok. Replace your ignition switch.
3b. If you have nothing at the brown starter relay wire then you have a problem in the wiring - could be the resistor wire or a connector issue. Go to test 4.
Test 4. With ignition switch in the off position, temporarily jumper battery voltage to the red-green wire of the ignition coil, with the wire pulled from the coil terminal. Measure voltage on the brown wire at the starter relay with reference to ground.
4a. If you have voltage at the brown starter relay wire, wires 16, 16B, and 262 are connected. Keep in mind that this test is with no load, and therefore could show a false positive. Go to test 5.
4b. (difficult) If you have no or low voltage, there is a problem with the wiring or connectors shown on the diagram. Check the 14289 to 14290 harness connector first, which if I recall is in the engine compartment. If that is ok, you will need to get up under the dash and check out the 14401 to 14290 connection point.
Test 5. At this point the ignition switch and resistor wire are good, and the wiring is connected and intact. However, there might be a significant voltage drop across a connection or bad area of a wire while the circuit is loaded, when the engine is running and current is flowing to the coil. What I do in a situation like this is to get a small needle and use it to probe through the wires at various points in the circuit along the way in an attempt to uncover where the voltage drop is occuring. In this particular case I would probably start at the red-green wire ahead of the connector at the coil. Note that these are all measuring voltage with reference to ground, with the key in run. Also note that as you probe along the way, as soon as you find some significant voltage, let's say over 9V for discussion purposes, you have isolated the problem between there and the previous measured point. If that first probed voltage is low, then go to the 14289 to 14290 connector, and measure the red-green wire on the 14289 side, followed by the 14290 side. If those are low, move up to the 14290 to 14401 connector under the dash.
+1 most typical cause of this problem is bad ignition switch from my personal experience. Experience of others may vary.
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The problem can be caused by a bad resistance wire, a bad ignition switch, or a disconnected wire. I am very suspicious when a tiny fraction of a volt is found. It could be your auto ranging digital meter is telling you something that may or may not be true. One of these little analog VOM's can give better information.
https://www.amazon.com/Gardner-Bender-GMT-318-Multimeter-Function/dp/B00291X79O/ref=sr_1_13?keywords=volt+ohm+meter&qid=1585014488&sr=8-13 (https://www.amazon.com/Gardner-Bender-GMT-318-Multimeter-Function/dp/B00291X79O/ref=sr_1_13?keywords=volt+ohm+meter&qid=1585014488&sr=8-13)
Again, measure voltage to see where the problem is. Then look carefully at all the places wires are supposed to connect to each other. It's cheap to measure voltage and look. It takes very little time. That way you can buy what you need and save money and time simultaneously.
I am sure that this is my problem. How can this wire go bad and how do I fix?
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I vote for a bad crimp in the somewhat new aftermarket harness (most likely in the resistor wire crimps).
Since it ran before and now does not and the symptoms you have shared, it makes the most sense.
What brand harness?
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I am back at it. Wow these are all great ideas. Not sure what brand it was that would take a lot of looking. However the connection for that resistor wire (heavy yellow) is a crimped then taped connection. Compared to the original that was molded rubber around the connection.
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Sorry for the delay getting back to this issue. it is certainly a crazy time.
I looked at most of the suggestions including going deep in to the brand new wiring harness with the thought it was the resister wire. Ultimately is was a simple as a starter solenoid. I wish I had the knowledge this group has but you guys are my go to guys for anything especially electrical.
thanks,
Kent
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I’m glad it was simple!