Motor cutting out every now and again

[gtxpress]

Although I lurk (I love to see what everybody else does) I find a problem I am not sure about.
67 FB 390 GT W breakerless ford setup.  I guess you might call it 'Duraspark I'  Motor is fine and although I have had some problems with vapor lock in Texas heat during the summer it is all but cured with the addition of an electric pump.
Last weekend we put on I guess 160  miles round trip.   On the way out  we were cruising on the Interstate (about 55) and it acted like it died, so I reached down and put the clutch in and noticed it was still running at idle, so we went on our merry way.
Coming back that evening, it did basically the same thing about 3 or 4 times but each time it did not die.  Just like a hiccup, like a direct short or something but I am almost sure it is not that. 
Question is there a way to check the module or could be the setup in the distributor causing the grief.  Any direction or help would be appreciated.

GT

[Joe-jdc]

Check for loose ground wires, and coil wires.  Also check your fuel filter for sediment build-up.  Joe-JDC.

[machoneman]

Check too for an unvented tank. Drive it a while, pull it over and immediately crack open the gas cap. If you get a big whoosh of air, check the cap and if equipped, the vent line from the tank or filler tube. 

[jayb]

I agree on the fuel, it sounds like it may be a fuel issue of some sort.  Usually an ignition issue will kill the engine, but a weak fuel pump, clogged fuel filter, hot fuel bubbling out of the vents into the carb, or other fuel issues can leave the engine running at low speeds while killing it at high speeds.

[machoneman]

Found a pretty good checklist, once one gets beyond the late model EFI stuff:

http://www.underhoodservice.com/Article/46386/diagnosing_intermittent_stalling_issues.aspx

[gtxpress]

Thanks guys,  I was hoping to avoid the troubleshooting issues and get straight to the problem OH Well!
Jay,  since it seems to cut back and run at idle,  you still think fuel?   Would the module do something similar or just cut out all togeher? 
Seems like I had an issue on a 73 460 ranchero I had but I do not remember the symptoms.   It may have just quit and I replaced the module

I will futz with it and see what happens.  Thanks

[rcodecj]

sounds like clogged fuel filter to me

[jayb]

Jay,  since it seems to cut back and run at idle,  you still think fuel?   Would the module do something similar or just cut out all togeher? 

I think the module would make it cut out altogether.  Never know for sure, but I think fuel is the more likely culprit...

[My427stang]

Does that setup use vacuum advance?

[bw_kc]

This happened to me this summer - intermittent cutting out.  I have an electric fuel pump with return line.  Suspected clogged filter.  Initially would only occur when the fuel was < 1/4 tank then got progressively worse.  I removed the fuel filter, checked it and found it was fine.  Guess what - had loose AN fittings connecting to the fuel pickup and fuel pump.  Guess when the fittings warmed up they expanded enough to "suck air".

Once I tightened the fittings the issue went away.  Drove the car over 1,400 miles on HotRod Power Tour without incident.

[machoneman]

Good point espcailly as our cars are now so old.  One should also check or just replace all the rubber in the fuel line from the tank up to the fuel pump.

A 'Net 54 poster awhile ago had a similar problem IIRC with sieve-like rubbers that let air in.  It baffled him until he tried to take off the rubber lines...they literally crumbled in his hands. New lines = problem gone!

[mammyjammer]

Another think to check is the Duraspark connectors. I was having similar issues and during the troubleshooting process I unplugged a connector and tugged on the wires. One wire was corroded to the point that it practically fell out of the connector.

[Cyclone03]

Is it DuraSpark module firing and MSD box or a DuraSpark box?

Ive been using stock type Ford Distributers modified with Dura Spark pick up triggering MSD 6al for years,I would say its my go to set up.

2 years ago I was on my way home from Ca. (I live in TX.) out in the middle of nowhere,IH10/IH20 Junction, Im driving along at 80MPH as I have been doing for hours, and the tach suddenly fluttered and the engine missed. As quick as it started it stopped. About 10 miles later  it did it again. Honestly the wind was bloweing pretty good and for some reason I carried on. No problems the next 300 miles and I was home.
One week later I was driving to the local cruise night and 1/2 a block from home the TACH again jumped and the engine began to miss fire. I turned the  car around and just as I got it heading the right way it again fluttered the TACH, this time it died. Some quick testing of the MSD and I determined the pick up died.
I had to order one and when it came in I cut the plug off and wired it in as I had been doing for years,when I started the car the timing was so far retarded it wouldn't start.?
I looked over the MSD instructions and found when wireing the pick up the connections that show the most RETARDED timing is correct. So I swapped the wires and started the car,a timing light showed my set 18*BTDC. I swapped the wires ,the car started because it was warm the timing was -5BTDC,more retarded, so I twisted the distributer to 20BTDC and locked it down.

Now did I kill it because I wired it backwards,or because it was a non Ford pick up? I dont know but I've never had one go bad in 25 years of doing that mod.
My point is before mine died it showed severel quick misses before it died completely.
Check that the wires are correct .
Now heres the dig against Chinese replacement parts. The wiring colors codes LOOKED correct but where swapped internally.

[gtxpress]

Thanks for all the great suggestions.  Cyclone came closet to the same type of problem although mine was just like turning the key off and a  pure ford setup.  Yesterday I spent some time looking over things and there was no fuel issue.  Tested the pickup (stator) and one of the reccommended tests failed.  So I took it off and examined it further.   For everyone familiar with the ford setup the pickup is encased in plastic.  Mine had a split all the way through and was about an 1/8 inch wide.  So I replaced it.  In thinking about the coil, it seemed to test OK but it was not quite the same values as expected so I replaced it as well.  The problem stopped.  I am not clear if it was the stator or the coil but evidently one or the other was causing a problem.  I took it out today and made several hits in the first three gears and cruised at different speeds between 50 and 90 with no apparent issue.  Again thanks for the help.  GT