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Why won't it start or run now

12K views 60 replies 20 participants last post by  Bad69cat 
#1 ·
I am out of ideas..... as well as my mechanic buddy's too so here it goes.

So 4 weeks ago I drove the cougar and it ran all fine. I came out to it after a meeting and it was dead. Well it would crank, it had spark, and fuel but wouldn't start. So I had to have it towed home. Over the past 4 weeks I have tried everything under the sun to get it running but with no luck. Engine just turned 10,000 miles after a full rebuild, with all new parts, water pump, alternator, carb, etc.

Checked for spark and had it.
Checked for fuel had it.
checked the rotor and cap, they are just fine (note points eliminator kit installed so no points or condenser)
Pulled the distributor to see if the gear was stripped, it was ok.
Reset the timing on it.
Drained the gas tank and put new fuel in it.
Checked the fuel pump.
Check the gear that the distributor meshes with and it was fine.
Pulled the front half of the engine off and replaced the timing chain
Got another distributor off of a known running 302 and installed it, but still won't fire
Checked all the wiring with the key in the 'run' position. I have power everywhere it should be.
Brand new coil with maybe 200 miles on it.
Replaced the rotor and cap just for kicks.

So I am out of idea's. I can't figure it out. It'll just sit there and turn over and turn over. I'm still trying to figure out why it ran just fine all day long and then I come out of a meeting and it won't start. As far as I know I've checked everything under the sun and I still can't get it to start. Any idea's??????
 
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#33 ·
I'm still researching the resistance wire to see how it works, but I suspect it may possibly have two wires running adjacent to each other made of different metals, one wire terminated at one end and the other at the other end and as the temperature changes, the resistance between the two wires changes.
 
#34 ·


Vin would be the 12V supply. Z1 would be the resistor wire. Vout is the wire from the coil to the distributor for the points. Z2 would be the coil.
The circuit is all in series. Power flows from the battery to the ignition switch. The ignition switch in the start position (starter spinning) feeds power directly to the coil positive terminal. The ignition switch in the run position feeds power to the coil through the resistor wire to the positive post on the coil. The power passes through the primary windings in the coil to the negative post on the coil. The points are a switch that connects the negative terminal on the coil to ground completing the circuit.

If you did hook it up the way you describe you would burn up the resistance wire.
 
#35 ·
I stand corrected on the connection of the points to the coil. However the voltage is still divided between the tach, resistance wire and the coil, limiting the amount of voltage available at the coil to less than 12V while the ignition is in the run position. My statement is true when people try to connect the red wire of a pointless ignition such as a pertronix ignitor to the positive side of the coil. Vout would be the red lead going to the ignitor and it would only see as much voltage as the coil sees. The black lead from the ignitor serves as the ground switch for the coil.
 
#36 ·
Not sure what the point is. A Pertronix works fine on anything above 6V. I've got hundredds of thousands of miles on the original Pertronix. Great devices.

Mallory Unilite conversion, very fragile. Be sure you are ready for long walks home, and have a cell phone to call a tow truck.

Had loads of trouble with Pertronix II. Received several bad ones from Summit Racing, had to get three before receiving a functional one.
 
#37 ·
Perhaps it would be helpful if you were to measure voltage at the ignitor/sensor on both the run and start positions of the switch?

I'm dealing with a similar issue right now on another points vehicle and the collection of voltage data helped out quite a bit with diagnostics.

My experience with Pertronix has been the same as Royce's. The original is great, when installed correctly. I've helped fix quite a few that were installed incorrectly by people who simply didn't read the destructions.
 
#38 ·
From what I have read, the pertronix ignitor 1 will work on less than 12V, but the ignitor2 and ignitor3 will not or at least not well.
 
#39 ·
Now that we have beat how the ignition circuit works to death, I had another thought. Not having my car handy here to look at, does the negative lead from the battery connect to the frame near the battery or does it connect to a bolt on the engine block? I have seen both, but not sure how this is done on our cars. Where does the ground wire from the points attach to ground? If its grounded to the block and the battery is grounded to the frame, is it possible that he is having a problem with the block not having an adequate ground connection to the frame? Sorry if that is a dumb question. Just trying to throw ideas out there that might help solve his problem.
 
#40 ·
Leroy, I completely agree with your last post. The stock location for the ground cable is the block. After 40 years anything is possible, no telling where it is hooked up now. This is a good thing to check. The points or the Pertronix are grounded to the plate they are attached to in the distributor. There is a small flexible braided wire that grounds the plate to the body of the distributor. This wire runs from one of the points mounting screws to a screw that runs through the adjacent plate and into the distributor body.

Royce and I disagree on the adequate voltage for the Pertronix (at least the I and II, I have not check out the III). Pertronix recommends 12 volts for all of these. I have found in some cases that the performance of the device as well as its durability are negatively effected. I cannot argue with Royces experience, but I suspect that the charging systems on his cars are top notch and he is getting a solid 14.4 to 14.6 volts from his alternator. This will go a long way to making everything work better.

A jumper wire from battery positive to coil positive will eliminate the ignition switch and the resistor wire from the circuit. The way to find a problem like this, absent the use of a good VOM, is to eliminate by substitution.
 
#47 ·
A jumper wire from battery positive to coil positive will eliminate the ignition switch and the resistor wire from the circuit. The way to find a problem like this, absent the use of a good VOM, is to eliminate by substitution.
Do this^ but jump the firewall connection, ignition switch, resistance wire, tach separately to determine where the broken circuit is.

That said, personally I dislike point eliminators i.e., pertronix, unilite, the Crane thingy. Sooner or later they always give problems (My experience).
Points work great. A quality set of points properly lubed and adjusted should last 5K miles at least.
I've had the best service from a good ol' rebuilt Duraspark distributor, HEI cap and wires, Duraspark coil and MSD.
 
#41 ·
Other than my lack of knowledge about how the points were connected to the circuit, I think we've been on the same page all along Bill. Bypassing the switch, tach and resistor wire is a good idea. Need to make sure it has a good connection, but can be easily disconnected to stop the engine.
 
#43 ·
Alright so here's more info.

I have run the Mallory 6100M points eliminator kit for 4 plus years and have never had a problem with it. I have it hooked up just like it says in the instructions (last picture) http://www.malloryperformance.com/pdf/6100M.pdf

Now I know that people have said that this will burn out my tach. Well, here's the thing. I have had no problems with the tach being hooked up. I run into the exact same problem if I have the tach hooked up or if I bypass it. It does the exact same thing even if I run the 12 volts from somewhere else heading into the red wire in the diagram. During all of this NONE of my voltages change. Like When the car actually starts vs when the car doesn't start. Everything checks out.

So I am about to change out the resistance wire. After that I have changed everything that I can think of.
 
#44 ·
Sounds like the Mallory Unilite module has burned out after four years. You have had excellent service, better than most Unilite users get. Time to get something better.



Alright so here's more info.

I have run the Mallory 6100M points eliminator kit for 4 plus years and have never had a problem with it. I have it hooked up just like it says in the instructions (last picture) http://www.malloryperformance.com/pdf/6100M.pdf

Now I know that people have said that this will burn out my tach. Well, here's the thing. I have had no problems with the tach being hooked up. I run into the exact same problem if I have the tach hooked up or if I bypass it. It does the exact same thing even if I run the 12 volts from somewhere else heading into the red wire in the diagram. During all of this NONE of my voltages change. Like When the car actually starts vs when the car doesn't start. Everything checks out.

So I am about to change out the resistance wire. After that I have changed everything that I can think of.
 
#45 ·
Royce I think he said it fires and starts when the key is in the start position, but dies when the key is moved to the run position. Wouldn't this eliminate everything past the coil as possible problems? Of course this would also negate my intermittant ground theory too, since it wouldn't fire in the start position if the ground wasn't there. He has already tried reverting back to points and I believe he said he tried a different ignition module. I don't remember him saying anything about trying a different coil.

If it starts when the key is in the start position and dies in the run position, I would think the primary suspects would be the ignition switch, wire from the ignition switch to the tach, the tach, the resistor wire from the tach to the firewall connector, the firewall connector itself or the wire from the firewall connector to the coil as far as hardware is concerned. The only other factor is that in the start position, the coil and ignition module are getting a full 12V, but in the run position they get less volts and current when the resistor wire is engaged.

Bob I did pull the NTC thermistor info from that article, but wasn't convinced which is why I was trying to find more information regarding the resistor wire. That and because if it turned out that the wire was actually a NTC thermistor I was curious about how it functioned. Later model cars seem like they just used a resistor mounted to the firewall with regular wire going to and from it, easier to replace than the resistor wire. I'm an EE too, but haven't messed with automotive electronics before so trying to get up to speed on the circuits in the last couple days to see if I could help and to learn for my own future reference. Doing the best I can with the limited schematics and information I've been able to find. You guys have more experience with these circuits in practice than I do and experience almost always trumps theory.
 
#46 ·
Royce I think he said it fires and starts when the key is in the start position, but dies when the key is moved to the run position. Wouldn't this eliminate everything past the coil as possible problems? Of course this would also negate my intermittant ground theory too, since it wouldn't fire in the start position if the ground wasn't there. He has already tried reverting back to points and I believe he said he tried a different ignition module. I don't remember him saying anything about trying a different coil.

If it starts when the key is in the start position and dies in the run position, I would think the primary suspects would be the ignition switch, wire from the ignition switch to the tach, the tach, the resistor wire from the tach to the firewall connector, the firewall connector itself or the wire from the firewall connector to the coil as far as hardware is concerned. The only other factor is that in the start position, the coil and ignition module are getting a full 12V, but in the run position they get less volts and current when the resistor wire is engaged.
I have replaced the coil, along with everything else (starter solenoid, ignition switch, and module, etc).

Here is the run through of what it doing again.
The car will sometimes start and run just fine. When it runs I have 12 volts heading into the coil and 6 volts heading to the distributor. The car can will be running just fine and then I will shut it off. 30 seconds, 5 minutes, etc later and it won't start at all. I still have 12 volts heading into the coil and 12 coming out heading to the distributor for starting purposes like it's supposed to. It will drop back down to 6 volts like it's supposed to as well. Sometimes though you can come back to it 5 minutes after you shut it off and it will turn right back on. Sometimes it'll run for about a week with no problems and then it just dies. When it dies it just turns over and over and over. During this time all the voltages still check out.

Now I have replaced the coil, starter solenoid, ignition switch, distributor, and the eliminator module (Note the old module still functions just fine as far as I can tell as I have had it back in too and the car does the same thing). I have tried heading back to points and it does the exact same thing. I have checked all the wire connections and everything checks out. I have tried bypassing the tach and the car does the same thing.

On a side note. I was going to install the resistance wire tonight. The only problem is that the the old resistance wire is tied into a 4 way hard plug while this new one is not meant for that type of connection. It's just a female connection on both ends. So I have not installed the new wire, but at the same time everything checks out with this old wire as far as I can tell. So I'm not going to replace it quite yet, and even then I don't see how you attach it since the terminal ends are different.

Thank you for all the help.
 
#48 ·
The problem here is bad troubleshooting technique. None of the parts needed replacing. It is does seem to be a wire or connection causing the problem. Like Art says just install jumper leads to temporarily install the new resistance wire. Should take about 5 minutes.
 
#50 ·
So are you getting spark when it won't start?

When it won't start, lift the coil wire from the center of the distributor cap. You should get a spark jumping the gap when you hold the wire close ot the center cap opening. You should even be able to hear the soft click of the spark. IF you are getting a spark here, then you need to pull a plug wire and hook it up to a plug that is grounded to the block to verify that you are getting spark through the cap and rotor.
 
#51 ·
I still get spark even when it doesn't start. I've pulled wires and checked and every one gets spark.

So here is what I did today on her.
I ran a new wire from the coil to my new resistance wire. I hooked in the resistance wire and by passed the tach. The car still won't start. I checked the spark at each of the cylinders and I have it. I still have 12 volts heading into the coil and 6 coming out yet it still didn't start. I then ran the test wire from the battery over to the coil to see if it would start. Still nothing........

So I pulled out the points eliminator kit and put points back into it to see what it would do...... and it started. The setup when used when it started with the points was the new resistance wire and new wire heading into the coil. I did not have the test wire coming over from the battery over to the coil. Yet here again nothing changed voltage wise I still had 12 volts going into the coil, and 6 coming out.

After it started I then pulled the points back out and put in the module again and it wouldn't start. However nothing changed. I still have spark at each one of the spark plugs, 12 volts into the coil, 6 coming out.....

So I am very lost on why it's doing this? I mean if I have fuel and spark then it should fire? Nothing voltage wise changes. And when I change from points to the points eliminator kit I still have spark at the spark plugs and no voltage change in the system. I'm concerned that I will go and drive it (not that I have much of a driving season left here in Utah) and that it's going to die on me in some parking lot. It's done it with the points eliminator kit and with points. I am so bewildered.
 
#52 ·
You have a weak spark because the points eliminator kit is no f'ing good.
 
#53 ·
Just for reclarification: When you are having the problem with it not starting, does it always start when the key is in start position and then die when you let the ignition switch move back to the run position or does it not even try to start when the key is in the start position? We are all looking at this from the perspective that it fires up and starts to run in the start position and then when you release the key and let it move back to the run position it dies.
 
#57 ·
Sometimes it'll start in the start position and other times it'll just sit there and turn and turn.

Not to be a smart A--, but if my front door key lock doesn't work, and I install a new one, and it works, REINSTALLING the lock that doesn't work doesn't seem to me like that will MAKE it work. It's dead. IMHO

I wish you well, this has been a long process, but I find it hard to believe it should have.

Nothing personal, for sure!

Dale in Indy
None taken lol. It makes sense.
 
#54 ·
Not to be a smart A--, but if my front door key lock doesn't work, and I install a new one, and it works, REINSTALLING the lock that doesn't work doesn't seem to me like that will MAKE it work. It's dead. IMHO

I wish you well, this has been a long process, but I find it hard to believe it should have.

Nothing personal, for sure!

Dale in Indy
 
#58 ·
If it is also not starting with the key in the start position, then the list of potential problems gets bigger. The problem is not limited to the run circuit. In the start position, the tach and resistor wire are bypassed potentially eliminating them as the source of the problem. Since you have had the same problem with more than one set of points and ignition modules and with more than one coil and more than one distributor, I am wondering if your problem is actually electrical in nature. Maybe its time to start looking at the fuel system, compression in the cylinders, etc.....Clogged fuel filter, Weak fuel pump, stuck check valve in the gas cap, vacuum leaks.....
A stuck valve in the gas cap would prevent air from being able to get into the tank to replace the fuel, creating a vacuum which will eventually overpower the fuel pump. When it won't start, remove the gas cap and see if it will start.
 
#59 ·
Well I wish I could report that the car started today, but it didn't. It's doing the exact same thing. I still have all the right voltages, and I haven't changed anything from the other day when it started with the points. It the start position it just cranks and cranks and occasionally it will try and start.

I have looked at the fuel system. The pump is good, there's no clogged filters, I drained the gas tank and put new gas in it. I've looked for vacuum leaks and haven't found any.

Why why won't you start? :cry::cry::cry::cry::cry:
 
#61 · (Edited)
I don't think he ever pulled the dizzy after it ran....I'm with Royce just thinking you have everything BUT a good spark. Is it bright blue and strong or whimpy and yellow (bet so)....?....I haven't run points in so many years I can't even tell you. Once I went to an MSD box and dizzy there has been no looking back - but I'm not worried about preserving original looks, I just don't like f-ing around under the hood when I want to go and get a bit of performance and reliability. Leroy brings up some good points as well, it could be your barking up the wrong tree, but I don't see where you have actually said the bypass (+ batt to + coil) worked? 5 min test to get you headed one direction electrically anyway, I'm currious if you can duplicate your problem with that?
 
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