Intermittent no start issue-UPDATED

[usraptor]

Okay, I'm at my wits end.  1970 Cuda, 440/512 stroker, Bullet custom hydraulic roller cam (Duration intake 234 and exhaust 241 at .050. gross lift .552 and .552, 108 separation,) ProMaxx aluminum heads. Holley Dominator intake, Quickfuel 880 CFM carb with vacuum seconardies, and electric choke with a spacer underneath it.  1 7/8" TTI headers and 3 inch exhaust.  Initial timing is set at 18 degrees and 36 all in.  The ignition has been converted to an electronic Distributor with the blue ECM.  It's a Summit Racing conversion.   The gap between the reluctor and mag.' pickup is .008.  Original wiring harness (in excellent condition) except for the splicing for the electronic distributor.  4-speed car.  After fixing an initial grounded ignition to the factory Rallye tach the car has not had any issues starting for the past three years.  Put it away for the winter and now it's a battle to get it started if it sits overnight.  Once it's started, it will repeatedly start right up for the rest of the day.  The next day the battle is on again. When I move the throttle I can see gas squirting out the venturi.  I can also see gas in the bowl site glass.  It seems like a no spark issue so I checked all the electrical connections for DC volts and this is what I came up with.  (I'm not real educated on what the proper voltage should be at each connection so any help is greatly appreciated.)  The two lead ballast resistor (new with the conversion) shows 11.60 volts at I assume what is the key side.  The other side shows 4.11 volts.  The positive side of the coil has 4.8 volts and the negative side registers 1.22 volts.  At the plug for the blue ECM the black wire with the yellow tracer and the blue wire both show 11.46 volts.  The two grey wires that go from the plug on the ECM to the two prong plug at the distributor are: the male end shows .5 volts and the female end is .0 volts. The Battery registers 12.46 volts.  I don't know if it makes any difference but the wire that comes from the alternator to the electric choke shows 10.69 volts.  The other wire on the choke that is grounded to a choke clamp screw shows .0 volts.  When I wiggle the plug at the ECM I can hear a clicking sound, possibly a spark) from inside the the distributor.  I've doubled checked the carb and intake bolts to make sure they are tight and that I don't have a vacuum leak. The new distributor, ECM and coil are three years old with just over 1K miles. If I use starting fluid it may catch for a moment but dies immediately.  After several unsuccessful attempts (with starting fluid) to keep it running it may or may not start and run.  Today it finally started without starting fluid but it was after numerous attempts.  I think it's just because the engine is flooded because of all the cranking to try and get it started, but when it first fires it backfires/pops through the exhaust for a few minutes before it clears up and runs smooth.  I also have two ground straps on the engine.  On from the block to the frame and a second one from the back of the intake to the the ECM firewall bolt.  All paint was cleaned off both end of each connection on each ground strap.  Any and all suggestions are welcome.   This is driving me nuts and I'm afraid to drive it in case after I turn it off it goes into no start mode.  As a side note what's the difference between the blue and orange ECM and which should my set up have? Thanks in advance.
UPDATE: Just went out after dinner to fiddle with the car some more.  It started right up but the popping/backfiring through the exhaust is getting worse?? My timing light took a dump so I can't check the timing.  However, the dist' hold down clamp nut is tight and nothing else has changed.   

[Bullitt-]

It sounds like you are testing the electrical system by turning the switch to run.
What is the reading on the Brown wire to the coil when cranking? SB close to battery volts.

[usraptor]

Bullitt, you are correct.  I was testing in the run position.  I'll recheck when cranking and let you know.

[usraptor]

Okay, I had to disconnect the coil wire at the distributor otherwise the engine would fire right up.  With the coil wire disconnected, I had 7.4 volts on the positive side and 2.44 volts on the negative side of the coil while my wife was cranking.  The coil wire was shooting out a nice strong spark onto the block while she cranked.  Since it was darker in the shop I noticed that I had a spark arc going from the negative coil post to the main center coil  wire cap.  I pushed the coil wire tighter and the arc went away.  I also, re-adjusted the float settings back to where they had been, below the half way point in the site glass instead of half way, and the the popping in the exhaust improved, but it's still there.  I'm 90% sure I have a misfire and one plug is fouled and either misfiring or dead.  Tomorrow, after I get home from fishing  , I'm going to buy new plugs to see if that solves the popping/backfiring in the exhaust and makes the engine run smoother. 

[Bullitt-]

It seems your loosing voltage on the Brown wire to the coil during cranking. I would be looking at the connectors at the steering column & bulkhead that is not seated correctly or possibly burnt. 

[usraptor]

Thanks, just got home from fishing.  I'll check those tomorrow. 

[usraptor]

Okay, so today I replaced all the plugs.  I included a picture of the old plugs here.  I'm no expert on how plugs are supposed to look but they look pretty dark to me.  Fouled?   I also went through all my electrical connections from spark plugs wires at the plugs and dist. cap, ballast resistor and ECM connections; undid all the bulk head connectors on both the engine and interior side and checked for loose and or burned wires and made sure everything was tight when I finished.  I must say for a 51 year old wire harness, it's in remarkable shape.  A little dirty maybe from the dielectric grease, but no burnt or loose wires.  I took pictures of all the connections as best I could but it's a little hard to do under the dash bent like a pretzel while you try and hold a flashlight and focus your camera.  Anyway, after doing all that, I gave the gas pedal one pump to set the choke, said a silent prayer, turned the engine over and it fired right up.  That in itself is an accomplishment considering that it has sat for 2-3 days since the last start up attempt and it hasn't started at all this year without numerous attempts, over and over.  I let the engine warm up and took it for a quick test drive and she ran perfect through all the gears.  No stumbling, etc.  Also, no more backfiring or popping through the exhaust.  I'll let her sit for a few more days this time and see if she fires on the first try again and report back.  I included the pic of the plugs and connections in case I missed something during my exam.  Thanks Bullitt for your input although I didn't find anything obvious, I think you may be right about a loose connection in the bulkhead.

[usraptor]

The rest of the under dash pics.

[RUNCHARGER]

Plugs are fouled for sure. That could be from trying to start it several times though.