Car Keeps Shutting Off

Hi guys, only had my Coronet a week and have broken down twice already so going to need some help.

It's a 69 Coronet with a 383 V8 and 4 Barrel Holley Carb.

Basically it starts up fine and will drive ok for about 30 minutes but then it will shut off when driving like it's run out of fuel(it has plenty of fuel in it), when you try and start it up again, the first few times it will start up briefly for a few seconds then shut off again, after the first few attempts it will then not start up at all, it will then need to be left for about an hour to cool down and then it will start up perfect and run for about 10 minutes before just shutting off again

The first time I broke down was the day I got it and I was with the previous owner still, he had a spare mechanical fuel pump and replaced that which I thought may have cured it but no joy.

He said he did have a similar problem 4 years ago when he first got it and he replaced the fuel pump pushrod and it's been ok ever since up until now, so could it be another faulty pushrod ? Or maybe a fuel evaporation problem ? If you look at the below pictures I noticed the fuel hose to the carb is sitting really tight on the distributor and the distributor was very hot, could this be the problem ? Maybe re-route it and get a braided hose ?

Car runs ok when it's driving and temperature is about 180F and goes to about 190F in traffic, it seems to shut off around the 190F mark.

The engine bay does feel very hot when you open the hood but am I right in thinking that's pretty normal for a big engine ?

Thanks for any help.

based on what you said and the previous owners story you might have perc problem. no vapor line, rubber fuel line laying on the hot block.

My diagnostic skills are poor, so I'll leave that to the experts. However that Accel coil is ancient, and the MSD box would be the first thing in the garbage if it where my car. A great ignition system for $169.00 can be found at: www.4secondsflat.com. Check it out everyone!

fix it right, don't start random replacing parts. I have a friend with that same ancient ignition and his car runs mid 10s

are you on commission ?
what is wrong with the setup? while what he is describing could be several thing this sounds more like a fuel delivery issue but yes, heat could be effecting his ignition....

Did you check for spark at the plugs when it quit? I would reroute the fuel line around the distributor rather than between it and the head.

Commission? No... I thought we use this website to share info with each other. I didn't tell him to get rid of the accel coil and or the MSD. I said what I would do if it were MY car. No one needs to be offended by my dislike for MSD from seeing so many of them fail. I happen to like that coil, and as far as 05dakota saying that his friend runs mid tens with that ancient set-up... maybe he could run high 9's with newer technology, but maybe the car would runner slower. Point being that I'm not trying to make anyone mad, and they should know that! GEESH! That would make me feel awful if I made an enemy over something that is intended to be friendly conversation between good Mopar lovin' people!

Sorry for the misunderstanding!

This sounds like a vapor lock/hot fuel issue. I would check for spark as was suggested to eliminate the ignition being the problem. You can get a spark plug tester for $12 or so at any auto parts store. Get the car good and hot to where it cuts off and then use the tester to check for spark.

If this is a fuel issue like vapor lock, you will need to get a fuel pressure gauge (0-15psi range) and plumb it in with a T-fitting on the fuel line or use the handy plug you have on your dual fuel lines. I suspect that when your car "shuts off" its fuel pressure if dropping to near zero and the motor is starving.

Get a spark plug tester and a fuel pressure gauge and do some testing. Been there, done that, got the tee shirt.

i was joking around with ya....

Another thing to check is the air gap between pickup and rotor lobes in the distributor. I'm not experienced with your system but have the Mopar Performance setup and have had to reset my air gap before.
Did you get the documents (installation instructions) for all the hi po components from the seller? You should be able to find them online if not.

Most likely it's either a fuel or ignition problem, determine which.
If it happens again,

-to check for fuel,remove air cleaner, work throttle while looking in the primaries to see if the acc pump squirts fuel

-to check for spark, pull coil wire from dist cap, hold it close (1/4")to the valve cover while someone tries to start it

This will get you started with the diagnosis.

As far as that coil, nothing wrong with it, I ran one in the '70s/'80s, although it may be incompatible with the MSD and overheating.
But I'm getting ahead of myself, first find out if it's fuel or spark.

agree with b5 bee. first figure out if it is fuel or spark.

even if you see fuel the first time it restarts, I would check again each time till it doesn't restart.

also I might try a can of engine start when it won't restart just to be sure.

I think it sounds like fuel as well, but you need to run the tests to be sure.

Thanks for the replies, I took it out again today to get a better idea and it broke down again

Cruising along it shuts off then briefly comes back again a few times before just quitting altogether, exactly like it's run out of fuel.

Took the air cleaner off and there is fuel squirting in the carb when trying the throttle, the AA recovery guy checked for a spark also and there is a spark too, he seems to think it's the fuel pump.

I'm still unsure though because surely if it's a faulty fuel pump or push rod it would not run hardly at all even when cold ? Why would it wait 20 or so minutes to shut off ?

Wouldn't start again for about 90 minutes then after that it started straight up perfect.

He also noted that the fuel hose going to the carb didn't feel like it has much pressure.

I think i'm probably just going to change to an electric fuel pump and see if it still happens.

Do you want to determine the failure or just throw money at it?

what is the temp under the hood when it dies?

is the coil hot! to the touch?

When it happens remove gas cap at tank and see if a vacuum has been created.
May have wrong cap and vent line is plugged.

I had this same problem with a small block. I finally figured out that the pick-up in the MP distributor was heat sensitive. When it gets hot the magnetic pick-up looses ability to send signal to the coil and soon as it cools even a little it comes back to life and runs normal. I replaced it and never had a problem after that

You gotta check for spark within seconds for a valid test. key "on", seperate the zigzag dist pickup connector (the male metal tip of the body half of the connector) and drag the male tip along the metal intake manifold to make/break ground while you with your other hand hold the coil secondary wire (dist end) 1/4" away from the intake (ground) & see if you get profuse sparks. this only checks/isolates the pickup/magnet/reluctor assy (mainly pickup continuity) but its a start

I had exactly this problem, this week.

Brand new zero mile MP distributor, with a pick-up coil that fails open circuit when the car has been running 10-30 minutes.

RapidRobert, your PM box is full, BTW.

To the OP, get a multimeter and measure the distributor pick-up coil resistance (unplug dizzy zigzag connector and measure across the distributor side contacts) immediately after the car shuts off.

I'm my case I got 1.2 million ohms. A serviceable pick-up will measure 300-700 ohms.

Did you check the ballast resistor? With the engine running, wiggle the wires connecting to it & see if it stalls.

Grab and wiggle connector where ignition switch wiring connects to under dash harness. Does engine die or continue to run? 5 second test.