At a total loss for an explanation

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67dart_drop_top

67dart_drop_top

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I have no idea what is wrong with my 67 Dart with a 273. I have had two other people look at it and throw guesses, but we have not made any progress.

Here is the problem: it starts great and runs fine for about a minute or two. Then it just quits--almost like the key has been turned off.

It has electronic ignition but cannot see how it could be a problem. The timing is set perfectly and not jumping. Fuel flow is not being impeded.

I am really at a loss. Anyone have any suggestions?
 
67dart_drop_top said:
Here is the problem: it starts great and runs fine for about a minute or two.
Click to expand...

Does it have a ballast resistor on the firewall?

Typically a ballast when bad will kill the engine as soon as you let go of the key. If you have one, you can eliminate it as a potential issue by using a jumper wire between the to wires that connect to it.

Check to see if it's not running out of fuel, clogged filter etc.

Coil would be another area to check.
 
I know you said fuel flow is not impeded. but when it does this try loosening gas cap and see if it's got vacuum pulling air in when you loosen it. Could be the vent for the fuel tank is plugged. How long does it have to sit before it restarts?
 
I had this happen to me once.

Pick-up coil in the brand new Mopar Performance distributor was going open circuit after a few minutes of running. Coil was obviously warming up and then failing once it reached a certain temperature. Instant loss of ignition.

If you're handy with a meter, disconnect the distributor fly lead when it shuts down and measure across the two contacts. You should read around 300-600 ohms. Open circuit is over a million ohms.

Cheers.
 
First thing to do is figure out if it's spark or fuel if you can. Couple things you can do........spend some time watching

Do what it takes to "rig" a fuel pressure gauge to the carb. Used to be/ still is you can buy an inexpensive vacuum/ pressure test gauge at the parts store and whatever fittings you need to "tee" the gauge in.

While you are at it, get some 12V LED or lamps with pigtail sockets, a couple, maybe

Rig one to the coil +, and the other to the "key" switch side of the ballast resistor

Start and run the car and when it stops try to notice.....did the lamp(s) go out/ dim, or did the pressure drop

If neither happened, might be spark

IMMEDIATELY crank the engine while testing for spark at the coil. If no spark, but your 12V lamp shows power, then it's "right there" in the ignition somewhere

At that point you may or may not be able to do more tests

WHAT KIND of ignition you have, IE Mopar ECU? MSD something? HEI? Distributor "ready to run" etc?
 
Could be the distributor pickup gap also. (about .008) is what it should be.

If it were me and I was positive about the fuel my priority list would be.
1. power loss at the coil when warm
2. ballast resistor (when warm)
3. distrib pickup coil gap
4. ECU

Have you tried a jumper wire straight from the battery to the coil+ yet?
 
If you have a timing light a quick check for spark is just hook the light up and see if you get a "pulse"
 
sireland67 said:
If you have a timing light a quick check for spark is just hook the light up and see if you get a "pulse"
Click to expand...

Or pull the coil wire and hold the end while jumping the solenoid with the key on.:D
Hey, it's faster.
 
Or have a helper stick the coil wore on their tongue while you crank it. But seriously, it sounds like ignition to me (electrical).
 
Dartswinger70 said:
Or have a helper stick the coil wore on their tongue while you crank it. But seriously, it sounds like ignition to me (electrical).
Click to expand...

Almost has to be when you have a sudden shut down instead of a stutter and die with a carbed motor.
 
distributor, magneto on bottom. my truck did this and this fixed it. $28 at Napa.
 
67Dart273 said:
First thing to do is figure out if it's spark or fuel if you can. Couple things you can do........spend some time watching

Do what it takes to "rig" a fuel pressure gauge to the carb. Used to be/ still is you can buy an inexpensive vacuum/ pressure test gauge at the parts store and whatever fittings you need to "tee" the gauge in.

While you are at it, get some 12V LED or lamps with pigtail sockets, a couple, maybe

Rig one to the coil +, and the other to the "key" switch side of the ballast resistor

Start and run the car and when it stops try to notice.....did the lamp(s) go out/ dim, or did the pressure drop

If neither happened, might be spark

IMMEDIATELY crank the engine while testing for spark at the coil. If no spark, but your 12V lamp shows power, then it's "right there" in the ignition somewhere

At that point you may or may not be able to do more tests

WHAT KIND of ignition you have, IE Mopar ECU? MSD something? HEI? Distributor "ready to run" etc?
Click to expand...
 
a volt meter works good, check the + side of the coil, what do you have?
 
Spark or fuel. One or the other is going away. Which one? By answering that question, half your possibilities are checked off the list in most cases.
 
rumblefish360 said:
I'd swap out an ecu
Click to expand...
Id say swap out the electronic distributor with a points style. BUT before you do this, bypass the ballast resistor, just jump it. 3 minutes of idle wont kill anything. The ballast resistor heats up and when it does the resistance across it increases, dropping voltage to the points (ECU) in the process. Theory was that at cold start, the ignition wants more (full) power, then it should taper dwon to save the points. great when it works but ballast resistor could be cracked and opening when it gets hot.
 
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