Big block won't run (annoying)

Yeah, same car again. '75 duster with '76 400 big block, 727 auto trans, older 8.75" rear. Thought I just about had it in running order but it has
recently developed a problem with either the fuel system or ignition system i think and will not stay running. It started probably a few months ago, only did it once in a while back then, now does it every time I try to start it. The car will fire up and run good for a few minutes then starts misfiring real bad then dies. Hard to start after that but will start then dies again. I suspected the fuel system at first, so I wrapped the fuel lines to make sure they weren't getting hot causing a vapor lock situation. Also pulled the fuel line off the carb when she quit and liquid fuel came out. Pump has good pressure, fuel filter is clean. The distributor is new as of a year ago, and I replaced the coil and the ballast resistor and the plugs and wires since the problem started and it hasn't helped. The battery is new within the last year as well. The engine has two ground straps, so I assume that is not the problem. The ignition control module is not stock; it is an ancient GP Sorenson module on the driver's side fender. I traced the wires to figure out where eveything is going and checked for continuity through the module, the hot and ground wires to the coil, the hot and ground wires to the pickup coil, and through the coil itself. Everything checks out, but the problem persists. I am out of ideas; can someone help me?
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If you drop a little fuel straight into the carb, does it start immediately then die? How long does it run good before it craps out again? How long do you have to wait before it will start and run good again? What I'm getting at is, if it runs good for a time then craps out, something could be marginal in the electrical system. When you pull current through electronics they will heat up. When things heat up they expand. When they expand they will separate.
I had a bunch of fuses in an old Datsun that worked for a few minutes. Then they heated up after being used and the element between the end caps would separate from one end (cold solder joint). After it separated the host unit would stop working or work sluggishly. Also had an instrument cluster in my daughter's car (2 of them) that had cold solder joints on the main board. When the car was cold all was well. After some current flowed through the system things would warm up and separate. I touched up all the solder connections that looked suspicious (cracked) and all is still well. This was a couple years back.
Heat (current flow) will cause things to expand and a connection will become open or intermittent. After it cools down (no current flow) it will contract and again make a good/better connection.

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Had something sounding familiar like this on my '79 Newport, 360, TQ. Had one float intermittently sticking in the down position and wouldn't close the needle valve.
Larry Behold Beware Believe

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The car seems to be getting fuel, unless the pump is only working intermittently? Pouring a little fuel in the carb does not really seem to help. I checked the floats on the Holley carb and they are ok and set correctly. The car will run for maybe 30 sec. to about a minute and a half before it dies. Before it dies, it starts misfiring real bad. You can really hear it through the exhaust, kind of an intermitant poofing sort of noise coming from both pipes. I can usually restart it after a little cranking, but it generally dies again right away or will turn over and cough like it wants to start but won't. If it is caused by electrical components, where should I start checking? The coil, distributor, plugs, wires, ballast resistor, battery, and battery cables are all new. Could it be a problem with the ignition module?
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Have you tried feeding it fuel thruogh the carb throat? Starting fluid in a spray can will let you know if its a fuel delivery problem or ignition. If you can keep it running, I'd say you've got debris in the carb. I remeber when alcohol was getting mixed to heavily into gas; that ate a lot of carbs on the inside.
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Was over trying to start the car yesterday. Could not even get it to start now, keeps smelling like it is flooded but will not start. let it dry out with the choke open for hours, still could not get it started and it smelled like gas again. I can see fuel coming out of the venturis when I open the throttle. I checked voltage from the coil to the distributor while it was being cranked over and it is making good voltage. However, I hooked the coil wire back up and pulled one of the spark plug wires off the plug and touched one lead of the multimeter to the wire and another to ground and got no voltage reading when the car was cranked over. I'm assuming I should be reading an intermittent voltage spike, right? So I'm thinking this means either the coil wire is bad, the cap and rotor are bad, or the pickup coil is bad, right? This just seems funny since the distributor, coil, plugs, and wires are all new. What do you guys think?
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Not sure what sort of millimeter you are using but any that I've seen can't measure that level of voltage (several thousand volts). You need to pull out a plug, connect the plug wire to it, set the threaded part of the plug on ground (head, exhaust, etc,). Then crank the engine and look for a blue spark between the anode and the cathode of the plug (anode is the center piece and cathode is the piece that curls over the center). If there is a blue spark then you are getting spark to the plug. No spark - no ignition. If you look at it in the dark it will be easier to see.

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On Sun, 7 Jan 2007 17:45:59 -0600, "Abby Normal"

Forget looking for spark - just grab the plug wire and crank <BG>. You will know FOR SURE if you have a spark!!!
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On Sun, 07 Jan 2007 17:27:27 -0500, "sackattack84"

Electronic or coil ignition? Single or double ballast resistor if electronic? Give me that information and I'll tell you how to troubleshoot it. I suspect you have a dual balast electronic ignition with a bad start resistor.
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It is an electronic ignition with a dual ballast resistor. Looks to be a pretty typical '75 A body system except for the GP sorenson ignition module in place of the stock Chrysler unit. The multimeter that I have will not measure the massive amount of voltage that the ignition system puts out, but it shows intermittent readings all over the place from zero to "infinity" (indicated simply by a 1 at the far left of the screen) when hooked up to the coil with the engine cranking. Constant zero when hooked to the plug wire.
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THE BEAST LIVES!!!!! Finally got it to start the other day and then it died again, so I had my buddy who was over spray starting fluid down the carb every time it started to die and we managed to keep it running. Replaced the fuel pump and filter and now she runs like a champ! I guess even though the pump was working, it must not have been pushing enough volume. Thanks for your help everyone!
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When I created my 55 street rod I had a small block that needed more fuel that the standard performance pump could deliver at high RPMs. I added an electric push pump back near the tank and that fixed it.
Good find and congrats.

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