mustang66289

I have a 1966 289 mustang and i am having this problem when i start it,it idles fine and sounds real strong but after a short while it shuts down like some one turned the key off. ive replaced the battery,altenator,voltage regulator,distributor,coil,spark plugs and wires. i set the timing and dwell it doesnt seem to be any of that because when it is running it sounds great, doesnt idle rough and rev's perfectly. any suggestions would be greatly appreciated.

dklistul

If it quits suddenly, it's probably ignition related (just like 90% of all fuel problems).

Next time it quits:

With the key in the ON position, check your voltage at the BAT (+) terminal of the coil. Should be 6 volts or so. If no volts, look for trouble between the switch and the coil (the resistor wire is part of this circuit).

If there is volts on that side of the coil, put your meter on the DIST (-) side of the coil. It should read 0 (ZERO) volts when the points are closed, and about 6 volts (same as the other terminal) when the points are open.

Of course, this second test could also be done with your dwell meter (I assume you have one since you said you set the dwell). You might run a long piece of wire from the DIST side of the coil into the car. Hook your dwell meter up to this wire and a good source of 12V. Watch the dwell meter while you drive. If it suddenly changes when the engine dies, your problem is on the distributor side of the coil. Broken (or intermittent) wire between the coil and distributor, faulty condenser, and the like.

I'd suggest starting on the DIST side of the primary (low-tension) circuit. Look for that bad wire by wiggling it while the engine is running.

You might also try wiggling the wires behind the ignition switch while it IS running. You might find a problem there, either with the switch or the wires.

Gun Jam

after it quits if you remove the air cleaner and with the engine off pull full throttle by hand as you look down the carb, watch for the jets of fuel from the accelerator pump squirt into the carb ventures. If you see them squirt then its even less likely a fuel problem. As stated above it sounds ignition related to me as well but this test is quick, simple and almost free so its worth the look.

-Gun

mustang66289

So when it shut down i checked the voltage on the positive side of the coil it was 5.5 volts and on the negative side it was 12.5 volts. I didnt look to see if the points were closed as i did it right as the car shut down in hopes i would catch the problem. It seems random, sometimes it will idle for a minute some times seconds. By shut down i mean it doesnt spudder or hesitate it just stops (just to clarify).

dklistul

If it quits that suddenly, it's not fuel. It sounds electrical to me.

It's hard for me to figure how you could have 5.5 on the + terminal and over 12 on the - terminal. The distributor doesn't manufacture volts.

One thing I neglected to point out is that the resistor wire will only reduce the voltage to the coil when the points are closed. That is, if the points are open, there should be NO current flow so the resistor wire doesn't any current to reduce. Therefore, if the points are open, you should read battery voltage on the + side, and 6 or so if the points are closed. The - side should read the same as the + side if the points are open (no current flowing), or 0 volts with the points closed (because the closed points connect the - terminal of the coil to ground).

Are you sure the coil is connected properly? That is, the + terminal to the ignition switch and the - terminal to the distributor. If reversed, it could explain the higher voltage on the - terminal, and the lower voltage on the other terminal would point to a high-resistance circuit through the points.

I'm betting you have a problem in the primary circuit, specifically on the distributor side of the coil circuit. Have you replaced the points and condenser? Condensers can do funny things when they fail, like short-circuit the points (most common condenser failure) leaving you with no spark, or fail open (less likely), leaving you with a weak spark.

One thing I haven't seen is, "What do you do to get it running again?" There could be a clue there, too.

mustang66289

I'm sure i have the coil hooked up properly (exactly how you said). when it shuts down some times it will start back up sometimes i have to let it sit with the key off for a couple of minutes. when its reluctant to start it fires up like its gonna run but just shuts down. If i stay on the throttle it will run longer but shuts down the same way no spudder,hesitation or rattle. It has a remanufactured distributor i just put in 3 or 4 weeks ago. i can drive it around but it shuts down like that randomly. when it shuts down i still have voltage going to the coil. The way it just quits running has me confused. is it possible the coil boiled some how?

dklistul

Did the problem exist before you replaced all those parts you mentioned in the original post? Or did the problem start after you replaced them?

mustang66289

It started after i replaced them. I put a dual plane intake manifold and 4 bbl carb on it and i had a backfiring problem through the carb so i replaced all the ignition system parts and this is where i am now.

Gun Jam

I wonder if its a broken wire to the coil? Use you volt meter and wiggle the wires after you get a reading and see if it changes.

dklistul

In our business, we call that a clue.

You said you replaced the distributor. I assume that it came with new points and condenser, correct? First thing I'd do is spend $5 and try a new condenser. Another thing is, like said above, wiggle the wire between the distributor and the coil while the car is running to see if you can get it to quit.

I had a pickup years ago that had an intermittent wire to the reluctor in the distributor. It would run great, then quit just as if I'd turned the key off. Most of the time, it would start right back up, other times it wouldn't start until after I coasted to a stop. That silly wire drove me nutz before I found it. But wiggling the wires from the distributor is what finally found it. A new reluctor in the distributor and I never had that trouble again.

If I was you, I'd concentrate very hard on the DIST (-) circuit from the coil. That includes the wire, points, condenser AND don't forget to examine the way the things are hooked up inside the distributor. You might have something that's really close to shorting to ground and when conditions are right, the spark goes out. The wire from the coil, the wire from the condenser, even the spring on the points can get out of position and cause trouble. If they touch ground, you roll to a stop.