Car stalls after 30-40 minutes

[BP23G0B]

Hey all,
I converted my 340 from points to electronic ignition in the spring.  I bought one of the kits from Mancini with the distributor, ballast, Accel coil, Accel wires, ECU and harness.  Since then it started to stall out when sitting after ~30 minutes (in gear and at idle).  I swapped the ECU with a brand new spare (Borg Warner chrome) and had the same issue.  I pulled the carb (Carter AFB) and it was pretty dirty so I had it cleaned and rebuilt and replaced the fuel filter.  After reinstalling the carb I had the same problem.  After that I realized the fuel to the carb was full of garbage (dirt, pieces of rubber hose, etc) so I replaced the rubber hoses, fuel tank, sending unit, fuel pump, fuel filter (again), and the hard line from the fuel filter to the carb.  I also had the carb pulled apart and cleaned out.  The only thing I haven't replaced is the hard line from the tank to the engine compartment.  I fired it up tonight and it was running great.  Smooth idle 1100-1200 RPM in park and ~600-700 in drive.  After 30 minutes it started stalling in gear.  I'm going to pull the new coil and swap the old one back in and see what happens.  Is there anything else I can try?  The ECU is bolted to the firewall with a repo mounting bracket and I ran a ground wire from the bracket to the firewall.  Could the ECU be getting too hot?  Could the new ballast be bad? 

The engine has the factory cam and heads.  It does have TTI headers and 2.5" TTI exhaust. 

[moparmaniac59]

Since it runs fine for 30-40 minutes, I'm thinking maybe it's a vapor lock problem. There are a number of things you can do if that's the problem such as a spacer plate under the carb. Reroute the fuel line/filter away from heat sources ect. Before you go do any of that, I'm sure some other folks such as Chryco will provide some valuable input.


                                                                   Matt B.

[johannes]

Run a Volt meter from +coil   to ground, and place it on the dash.
Normally it should read ca 9V with the engine running.
If, your el systems fails after some time, this will show up as a voltage drop....
Typical problems are;
poor bulkhead connection.
Overheated ballast resistor.
Poor ignition (key) switch

[MEK-Dangerfield]

Swapping the coil is a good guess. What you haven't answered is if it restarts and runs fine after sitting for a few hours.

[dodj]

Hey all,
 After that I realized the fuel to the carb was full of garbage (dirt, pieces of rubber hose, etc) so I replaced the rubber hoses, fuel tank, sending unit, fuel pump, fuel filter (again), and the hard line from the fuel filter to the carb.  I also had the carb pulled apart and cleaned out.  The only thing I haven't replaced is the hard line from the tank to the engine compartment.

When it stalls, see if you have any fuel in the carb. I'm thinking your filter is getting clogged with yet more crap in the fuel.

[BP23G0B]

Swapping the coil is a good guess. What you haven't answered is if it restarts and runs fine after sitting for a few hours.

That's exactly what happens.  Once cool it fires up and runs fine for another 30 minutes.

[MEK-Dangerfield]

That's exactly what happens.  Once cool it fires up and runs fine for another 30 minutes.

As frightening as having crud in the fuel system is, this sounds like a heat issue. Swap the coil and see what happens.

[BIGSHCLUNK]

I'm thinkin'ECU, had that issue on a duster years ago... 

[tman]

Any issues before converting to electronic ign???  If not, then they started when installing the new system.  Ballast gets real hot under normal circumstances, but could break connection when it gets too hot, then you have connection once it cools.  Make sure the wires to the ballast are tight in their respective connectors.  I had similar issue and one of the wires was very loose.  Just lightly pull on the wires that are crimped on the connector.  I pulled a wire out and finally found my problem.  I ended up re-crimping the wire to the connector then soldering it.  I too went through the changing out ecu and ballast, until I found the real problem. 
Vapor lock could be an issue too if your wiring is 100% ok? Is this occurring in real hot weather?  But again, if you did not have this issue before the conversion, then its usually something to do with the conversion.   

[Chryco Psycho]

the 3 components that typically do this are the Coil , Pick up coil inside the dist & the ECU

[ShelbyDogg]

Lke Chryco says, those 3 components supply spark.   I suspect your pick up coil.   As soon as it happens again, pop off the distro cap. Crank the engine so you can turn the rotor back and forth by hand, where a reluctor tooth passes the pick up's metal center.  Take the cap's center coil wire and lay it next to the manifold. Turn ignition on then turn the rotor back and forth.  You should get a 1/2" spark jumping to ground.

No spark? Plug another distributor onto the plug, then spin the shaft by hand to see if it sparks.

I ALWAYS check for spark 1st unless I see fuel at the base of the carb. (stuck float)

[TinCuda]

You have a bad coil.


.,

[BP23G0B]

Thanks for all the input guys.  I swapped the ECU, ballast, coil.  I double checked the harness and cleaned up a coulple of the connections.  I wasn't able to sort it out so the old distributor is back in and the electronic stuff disconnected.  It seems to be running fine now.  I sounds like it did before I put the conversion kit on and this is with the new coil and ballast. 

[BP23G0B]

OK.  So the new distributor is out, points distributor is in.  I'm still running with the new Accel coil (PN 8140) and new ballast.  Just took the car out for a quick drive.  It was running for 50 minutes or so without the idle issue.  My vacuum advance isn't set right.  I disconnected it, and plugged it and carb up after I got some throttle knock at 30-35MPH.  Had it on the city streets and highway.  Had some bark/bog under load at WOT in 3rd gear on highway. After that no issue.  So, with all the input from you guys, I think the only thing(s) it could be is the electronic distributor/pickup, electronic harness, or both ECUs.  Weeks ago when troubleshooting I did swap ECUs without disconnecting the neg wire to the battery which I later found out was a no-no.  Maybe I fried both ECUs?  Don't know.

[ShelbyDogg]

probably the distributor. It's the only thing not changed when the problem came back,