360 Running Issue(s)?

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DartGTDan

DartGTDan

'71 Dart GT Fan
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My buddy has a '65 A100 pickup with a 360, 727, 8 3/4" with a 3.23:1 sure-grip, Edelbrock Performer intake & 1406 600cfm carb. This truck has a problem that appears to be getting worse.

It will start and run for about 10-15 minutes. Then it develops a sputter/fart/die scenario. However, it will re-start nearly immediately and run for a few seconds before the sputter/fart/die scenario repeats.

He thought it was vapor lock and rerouted fuel lines, wrapped the headers, put a 1/2" carb spacer, added an electric fan, etc.... (I thought vapor lock would take some time to "cool" the fuel to a liquid state again). We think we've ruled out vapor lock.

We started thinking electrical. Discovered the distributor had a bent shaft (however that happened?). He purchased a new Mopar Performance electronic ignition distributor. He's also replaced the ignition ECU module, coil, ballast resistor, spark plugs, and plug wires. The vehicle does the same sputter/fart/die scenario. During the sputter/fart/die scenario the (aftermarket SunPro) Tach needle is bouncing all over the place. The ECU is mounted in the cab of the truck not underhood, so no heat issues and yes, he has a good/seperate ground to the ECU.

Our next plan is to run new wiring from the ECU to the distributor, coil -, and Ballast Resistor (IGN (RUN) side).

We are both losing our hair over this one (on fist full at a time), and any help/ideas/direction is appreciated.

Thanks!!
 
I really can't add much as you've already covered most anything i can think of. Member "67Dart273" is good with ignition and wiring. Hopefully he'll chime in with some advise.
While i was typing this i had a crazy thought......try unplugging the tach from the system? Not likely it but easy to try.
 
This just "sounds" more like fuel

I would get "rid of" the entire wiring harness, electrically speaking. Got downtown, NAPA, Rad shack, etc and get some alligator clips, and make up a couple of good heavy, no14 or so clip leads. Determine which side of the ballast is the "switch" side, and hot wire the ignition by clipping from that side of the ballast directly to a battery point, starter relay, etc.

IF the problem goes away, you know its in the harness.

Also remove all the connectors, distributor, ballast, ECU, inspect for corrosion, and "work" them in/ out to "scrub" them clean, and "feel" for tightness of the connectors
 
Today we took the vehicle's entire fuel system completely out of the equation. We put a small electric pump from a gas can directly to the carburetor. Fired it up and it ran for 10-12 minutes then did the "sputter/fart/die" scenario AGAIN. I believe we can now eliminate the fuel system from the equation.
When the engine is in the "sputter/fart/die" situation the tach needle is bouncing quickly and erratically, and all other gauges read normally (including ammeter). The ammeter leads have not been shorted together (bypassing the ammeter) as of yet. That is still on his list of things "to do".
Any other advice or direction?
 
If not fuel, then spark. Install a "spark tester" in series with the #1 plug. Cost ~$4 at Harbor Freight or much more elsewhere. You should see steady flashing of the neon bulb. Also try a timing light and see if you get a steady flash.

Did you try the basic electrical hookup that 273 recommended? My guess would be a bad ground to the ECU body, but could be the ECU itself, a bad key switch, bad bulkhead connection, or erratic ballast connection. I don't see how bypassing the ammeter would help this problem. Run a 12 awg wire to coil+ from the battery to bypass all the supply wiring, but for <1 min or the coil and/or ECU will get hot.
 
Numba ONE

Unhook the tach

2. Try "hot wiring" the ignition system to eliminate ALL in - car harness wiring. Identify where the ign switch feeds the ballast (this is a 2 terminal ballast, right?) and hook into that with a nice big wire, at least no14, and run it out to something "solid" such as the big battery stud on the starter relay. Note that this WILL power the vehicle igntition until you unhook it.

Make sure you have compatible ballast/ coil. Did you buy 'em in a kit? or just a new MP distributor?

Be SURE of your ECU ground.

Remove and inspect all ignition system connectors, the ECU, the ballast, the distributor. Look for corrosion, "work" them in/ out several times to scrub the terminals clean, and "feel" for tightness in the connectors.

Consider replacing the ECU pigtail and distributor connector (or the harness) those connectors CAN break internally. You can wiggle them, while running, though, and get an idea.

Check charging voltage at the battery, just for drill. Warm it up, get the battery "normalized" and see what you have at a good fast idle.

When running, feel the coil (NOT the ballast!!!) for heat, and wiggle connectors, especially the bulkhead connector.

I WOULD at least temporarily, run a big wire, at least no. 10, directly from the alternator to the battery (starter relay stud)

S' all I can think of for now.

!!!OH!!! Look at the coil Is there a capacitor (condenser) on the coil? Which SIDE of the coil, (should be on positive side) Unhook it for now if there.
 
I was thinking the same thing about charging voltage while its running at the point when the problem occurs. An over-charging electrical system will have adverse affects on the ignition coil saturation & the ecu. Same thing if its under-charging. Also eliminating the tach from the equation would be good as well as you may have a tach shorting out or a connection problem there. You didn't mention if the dist cap & rotor were replaced, I'll assume so since it's a new dist.
I'd also suggest if the ignition checks out taking a good look at the accelerator pump in the carb. Good luck!
 
Now that you know thr problem is electrical you have to suspect everything that can heat up and break down. The one thing that you touch to make it run again is the ignition switch so it is highly suspect or at least in my mind it is.
 
Hey all,

We think we've discovered the issue. The connection between the distributor and the ignition control module appears to have been damaged. We "overlayed" a new distributor harness and soldered connections to within 6" of the ignition control module's 5-pin connector.
It started up and ran great!. We took it out for a 40 minute cruise with no issues!
He's a happy camper!

Thanks for all the input!

We're now ready for the Woodward Dream Cruise!

Dan
 
Check the "double bullet" connector on the distributor. I have seen a few new ones that were not correct, and suspect there are bad parts in the supply chain. The factory ones have an extended male terminal, whereas a reluctor pickup I bought thru rockauto had a regular bullet connector with a shorter male pin like on a trailer or appliance connector. Those don't make assured contact with the engine harness connector.
 
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