Engine stops running for no apparent reason

[ward 57]

These were the exact symptoms I had. Backfiring indicates that the carb IS getting fuel. No fuel no backfiring as raw fuel is not getting into the exhaust.
My problem was a failing coil resistor. Intermittent connection that would come and go as the vibrations would connect and then disconnect killing power to the coil. Ever have a light bulb burn out but as you wiggle to remove it the filament would connect again and would light for a moment? same scenario.

[voltron]

I noticed in one of your photos that the old style distributor to coil pigtail wire with the stud insulator that will ground out on the inside of dist due to wear and tear and break down of the insulation. The superior replacement has a rubber molded gromet that replaces the troublesome stud and bakelite insulator feed through. The Tbird suppliers have them for about 10 dollars. It appears that the resistor is not there, you should get one.
The electric choke wired to the coil just doen' t set right with me.

[55blacktie]

If you go to y-blocksforever.com, you'll find recent posts regarding attaching automatic choke wiring to the coil. Ted Eaton (eatonbalancing.com) recommends running the choke wire directly to the ignition switch, not to the coil. Dan Jessup (Hot Rod Reverend) recommends the same, along with using an inline fuse.

[Fasteddie4007]

I did order a resistor and can install it tomorrow. How should it be wired? Also, I will rewire the electric choke and take it off the coil. Just to be complete I will also check the fuel bowls and float levels even though I am starting to lean to a problem in the ignition system. Thanks for all the advice, I will follow it where ever it leads to fix this once and for all.

[MarkR]

Rather than retype all this here is a photo from my Holley installation manual. I’ve never had an issue following these instructions for the chokes.

[ward 57]

I did order a resistor and can install it tomorrow. How should it be wired? Also, I will rewire the electric choke and take it off the coil. Just to be complete I will also check the fuel bowls and float levels even though I am starting to lean to a problem in the ignition system. Thanks for all the advice, I will follow it where ever it leads to fix this once and for all.

Check my photos. red & green coming from the ignition switch. Red to the resistor & green going to the coil. simple wiring. Then from the resistor to the coil with another wire. The only two which should be there. ( if both still exist in their original colors ) I honestly think it's ignition not fuel. Backfire can not happen without fuel.
The resistor is not expensive and is one of those things that have a limited lifespan but can cause havoc when failing..

[Fasteddie4007]

Sorry, but I didnt notice your wiring pictures. I saw some others that where not real clear.

[ward 57]

Sorry, but I didnt notice your wiring pictures. I saw some others that where not real clear.

https://www.vintagethunderbirdclub.net/ ... 88#p134288

[Fasteddie4007]

Just came back from disconnecting the 12v wire going to the choke, have the choke held open with a nytie and started the car allowing it to idle. After 5 minutes of idling the car wanted to shutoff and when I restarted it ran very rough and would not stay running. Did that 3 or 4 times with sake result. Voltage at distributor was down to between 3-5 volts but about 7 volts at the distributor side of the coil. The coil is getting very hot and reading as high as 15.7 volts on the 12v power side. Voltage regulator cap says its 15v 30amp is putting out 13.8 volts. I have ordered the distributor primary replacement terminal and I am wondering if I should replace the coil also.

[ward 57]

Just came back from disconnecting the 12v wire going to the choke, have the choke held open with a nytie and started the car allowing it to idle. After 5 minutes of idling the car wanted to shutoff and when I restarted it ran very rough and would not stay running. Did that 3 or 4 times with sake result. Voltage at distributor was down to between 3-5 volts but about 7 volts at the distributor side of the coil. The coil is getting very hot and reading as high as 15.7 volts on the 12v power side. Voltage regulator cap says its 15v 30amp is putting out 13.8 volts. I have ordered the distributor primary replacement terminal and I am wondering if I should replace the coil also.

I hate to harp on the subject, but is the resistor in line to the coil? The regulator sounds like it is working properly, 15V is the max output but 13.8V is right in the working range. If the coil is getting that hot it may have an internal short. Age related, They don't last forever. If you can, replace with the original style yellow top. I have heard they are the most reliable VS an auto parts store generic.

[Fasteddie4007]

I ordered a new coil, the primary terminal on the dist and the double wire for the resistor hookup. In a few days I will have the parts and I will have the resistor installed with a new coil. Hopefully that will solve the problem.

[Fasteddie4007]

I am assuming 12v into the resistor then out of the resistor and into the distributor? Is there an in and an out on the resistor for the wiring? It appears that it won,t matter but I would rather double check first. Parts are here so should have this done in the next few days.

[ward 57]

The way mine is wired the 12v from the run position of the switch goes to the bottom of the resistor the wire from the top goes to the batt side of the coil along with the start position wire. so two wires on the batt side of the coil and one from to ign side to the dist.

[Fasteddie4007]

so today I installed the new moulded primary wire out of the distributor, new yellow top coil and the ignition resistor. 12 volts to resistor then out of resistor to bat side of coil. Other side of coil to distributor. When I first wired it car would not start. Check spark at coil and I had spark but not very powerful. Next I checked spark at the plug and no spark.
Thought I had it wrong so I brought the 12v to the coil first then through the resistor , car started but ran bad like the problem I was having occasionaly.
Went back to the first way of wiring and decided to start changing parts in the distributor one by one. First the rotor, made no difference. Next, I changed the condensor and like a miracle the car started immediately and ran perfect!! Let it idle for 45 minutes and it never missed a beat. Took it out on a 10 mile run and performed flawlessly!! Still haven't changed the points or the cap but probably will so everything is new at 1 time.
Not sure what the second wire is for that you are referring to on your hook up. Anyway, very happy that this gremlin has been chased down and hopefully something else won't pop up.
Thanks to everyone for all your help!

[ward 57]

There should be two wires from the ign switch. One from the start position and the other from the run position. It sounds like you only have the run position wire. I'll bet it doesn't fire until you release the key from start unless someone spliced the wires together not knowing the difference. The start position wire bypasses the resistor to give you better spark on start up. Helpful when the engine is REALLY cold. I'll attach my photos and description link. As you found a bad condenser can cause stupid problems also.
https://www.vintagethunderbirdclub.net/ ... 88#p134288