Zcarlover

Here's the problem. My 73 240 cranks, idles and runs great for about 30 minutes. It then will just shut off, no warning or sputtering, just shut off like you killed the ignition. If you let it sit for a couple of minutes it cranks and runs fine for about 10 minutes and does the same thing, shuts down. I have rebuilt the distributor,plus new points, new rotor, new cap, new condenser and new spark plug wires. The coil is about 6 months old and seems to be okay. It doesn't get extremly hot, but I'm wondering if that may be the cause. Could it be something else like the ignition switch or fusable link?
HELP!!!!!!!!!!

NismoPick

Have you sync'd the carbs? Cleaned them? Checked them?

Zcarlover

yes, its definetly electrical.

NismoPick

Well, when a motor won't start back up, there's only 2 main probs:

#1... no spark

#2... improper fuel mix


Do you have spark when it won't start? Does it have fuel? Is it flooded? What do the spark plug tips look like?

Zcarlover

It will start back after a couple of minutes. Runs fine for a few minutes then shuts off again. The carbs are fine and are synced. The plugs are a golden brown to dark brown color. It is not flooded. Its like you turn the swirch off. It will crank back immediately and then act as if it is fine , good idle and then you start to drive and about 5-10 minutes it shuts off again. Thats why I thought maybe one side of the coil is bad.

NismoPick

You didn't answer the main question... Is there spark when it won't start?

Zcarlover

Can't tell you that because it will crank back up immediately after it shuts down. Sorry.

NismoPick

Ah... first you were saying it will restart after a few minutes, now it's right away...

Anyway, did you replace all those ignition parts and THEN it started acting up, or did you replace those parts trying to solve this prob?

Ratfink

If the ignition switch would be the problem, it would always be the problem. Same with a fuseable link. They burn, and that's it for 'em.

Choke is not on. Right?

You have the coil running through the factory resistor?

Can you get the engine hot at all?

Sounds like your over fueling to me. But, that is just my instincts. You say it's electrical.

Hard to tell without being there.

You not in the PHX area of AZ are you? I would run over and check it out.

Zcarlover

Yes the engine gets hot enough to run. I cn run it for about 30 minutes and then it just shuts down. When it does this the first time it will immediately start back up and run, then it will make it maybe, a few miles and shuts off again. When it shuts down this time it takes a couple of minutes before it will crank and run. Then it does the same thing over again. If the car sits and gets cold it will run fine for about 30 miles and then starts its routine of shutting down. I replaced all of the ignition parts after it started doing this and thought I had it fixed because the first time I drove it after replcing everything it ran fine. I just didn't drive it far enough for it to start shutting down. The only thing I didn't replace was the coil, because I had already replaced it about 6-8 months ago.

snwbrderphat540

coil is possible, when they get old they can get to hot and just stop creating spark, usually thats involved with the loss of internal oil at the same time so if you unbolt it and can shake the coil and hear the liquid in it slosh could be the culprit. but you need to do some diagnosing not just replacing. next time it dies try cranking it to start it up again RIGHT AWAY dont wait for **** to happen, if it just cranks and doesnt fire up you need to re-create that situation but as it cranks have someone check for spark, if the sparks there, its possible your flooding the engine, if the spark isnt there, time to go back to that problem

rtmorgan

sounds to me like the coil is getting hot and when it shuts off it starts to cool then the car starts and warms it back up and it fails again etc. etc.

Zcarlover

Thanks for all the info guys. I do appreciate it. This the greatest site on the internet. I have ordered a new coil and ballast resistor. It is the wierdest problem I have encountered since I have been messing with cars, and thats about 35 years. I have had 9 z cars and none of them have ever acted like this one. I think it might be haunted...lol.
Again thanks for all the help. I will install the new coil and resistor and let y'all know if that is the problem.

snwbrderphat540

why? why didnt you do what i suggested first to TEST and SEE if there was spark before spending more money? for all you and i and us know it has perfect spark. also shaking that coil will tell you if the oil level has gone down inside it. kinda jumped the gun on that one no? might have been something as simple as a loose connection or old wires.

Zcarlover

Already changed all the wires and connectors to the distributor , ballast, coil and evrything on the inside of the distributor. I took the distributor apart and rebuilt evrything inside, including the bearings on the vacuum advance plate. I tested the coil this afternoon after one of it's episode and only got 0.42 ohms of resistance. After it sat for less than 2 minutes it gave me 1.075 ohms of resistance. That is why I ordered a new coil. I was getting a good arc from the coil up until it had it's episode, then I checked the resistance. It was hard to check for spark because it seemed to fix itself so quickly that by the time I pulled the coil wire off and spun the motor it would have spark again. I didn't post all of that because I was in a hurry. Sorry

snwbrderphat540

sounds fair just wanted to make sure you didnt jump on the first logical culprit without testing. i was concerned for your financial aspects haha. hope that fixes it all. out of curiousity where was the first coil you got from? and where is this new one coming from?