electrical problem very puzzled, 440 motor

I'll try to make this short. 75 Dodge truck 440 motor stock electronic distributor orange box. last few days truck would die after driving for a while, would not start, no spark. sit for a while then it would start right up and run fine. did this a few times, so today I brought an extra control box, ballast resistor, and coil. drove around until it did it again. no start no spark. changed The Orange Box nothing, change the ballast nothing, change the coil started but was backfiring and would not stay running. finally gave up had to be towed. now after sitting for a couple hours I can't believe it but it started right up and ran fine. idles perfect. Ideas please???

bad ground between battery, block and control unit.

It could have something to do with a loose connections that is affected by temperature. I had a similar problem with an electric fuel pump. It left me stranded many times. It would only do it when the car was hot because the resistance in the loose connection on the inline fuse to the pump would change with temperature. I say check all your connections.

yes I'm going to check all the connections tomorrow. was getting plenty of gas to the carburetor. a friend of mine suggested the pickup in the distributor possibly, it is an older distributor.

I had an issue exactly like that--ran good cold for a while until it got warmed up, then would die. Let it sit and cool off and it would start right up. Repeat.

Turned out the coil was going bad and was affected by the heat coming off the intake.

You sure the one you put in was good? Did this problem start out of the blue, or has it been getting worse over time?

sure sounds like classic ECU or coil acting up. do a quick visual on the pickup/reluctor (anything loose). next time it does it (1) pull coil wire (dist end) & hold it 1/4" from intake (ground) (2) pull yellow wire with tracer off of starter relay to disable the starter (3) turn the ign key to "on" (4) you seperate the dist pickup zigzag connector and drag the male terminal on the body half of the connector with your right hand along the intake surface which will make/break contact just from the dragging due to the surface irregularities in the intake metal surface (5) at the same time with the coil wire in your left hand see if it makes sparks to the intake surface. Work FAST as you need to do all of this while the pickup is still hot. holler back EDIT No need to pull yellow wire off of SR (was thinking of a (similar) issue)

Check the bulkhead connectors..
These get oxidized, loose over the years and then U have bad connections..

Pop the connectors off, burnish the contacts, crimp down slightly the female tab connectors, apply dia-electric grease, reinstall...

Just my $0.02...

It almost sounds like the replacement coil was hooked up backwards.

Check the air gap and resistance on the pickup in the distributor. Was common fail point way back when...

check coil hook up, I know it was backfiring and popping through carburetor, but I never change the coil back to the other one and like I said it ran perfect tonight idle was nice so I'm thinking coil is hooked up correct.

bulkhead connectors are all good wiring harness was replaced with an NOS one a few. years ago.

That means zero, assuming a new, or newish item especially if NOS is "good" usually ends up biting you in the derriere.

Too many times NOS meant didn't meet spec for the factory so it got put into the parts pipeline.

All connections checked, all cleaned and look good.just tried another coil, ran for a while then died. Tried a good orange box off a running car, nothing. I'm thinking distributor? Only thing I have not changed.

My test will confirm or elim the dist WO pulling it

Rapid, I did your test and spark from coil wire to intake as I dragged male end of connector. So it has spark with your test. Got running again,idled smooth for few minutes, then started backfiring as it was idling. Then died.

get the dampener slit a bit further CCW than the left edge of the timing tab (so you are ~ 20 deg or so BTDC) then with a 1&1/4" socket/short extension/breaker bar turn the dampener carefully back CW till the tooth is dead even with the magnet then replace the dist and turn the housing till the magnet is dead even with the tooth which will put you back to your orig position for an easy fire up. Or pull the center clip/reluctor and replace the top plate/pickup assy. I'm assuming you did it when hot. You might ohm the pickup when cold and when hot & acting up just for a baseline. If you swap complete dists grab a helper & plug each dist in (the zigzag connector) & spin each ones' lower shaft by hand (key on) & see if you get sparks from one, out the coil wire but not the other. The suspected offender will be cold which will skew the test but I always get a kick out checking em that way.

Thanks, I'm going to pick up another distributor he says is good. Sounds like your saying it might be the pickup in the dist. Maybe that explains running good then backfiring a bit, then running good again.

Ok any way it could be the ign switch? Got it running, and turned on headlights and it died. Volt gague showed it charging, but I wiggled the key and the needle bounced up and down then stalled. It is the original switch

to bypass the ign sw jump fire from the starter relay large batt stud to the blue/yellow wire on the ECU pentastar connector and to the upstream (blue wire) end of the ballast & fire it up & see if it stays straight

Had this happen to me. Same symptoms as you're having. Reset the gap as per factory specs and away I went.

That small voice upstairs keeps sayin coil or ECU so please keep us updated. the dragging test would for sure confirm or elim the pickup (elim the pickup means it could be the wiring/ecu in that system, anything other than the pickup) IF the system was totally dead but with it like it is now that skews everything (to some extent). I just had a coil be pretty much the same (FBO black coil) & towed home & the coil sparked. Changed it & all good in the 'hood. Had an ECU do similar & it was the ECU

I did your dragging test, if I did it correctly it did have spark.I cleaned all the bulkhead connections several different ECU s, several coils checked all the grounds nothing. I think I'll just get the MSD distributor and coil and just run the three wire system.

Yes you did it correctly & my bad I missed your info that you had replaced the coil and ECU several times.

Robert, I did have spark.I when I did your test, so that would show pickup good?.

that test takes the pickup out of the picture cuz you are directly triggering the ECU with the dragging as opposed to the pickup electronically triggering the ECU so with it sparking that points to the pickup as the culprit but what skews things is that the offender is acting up part time (from the heat) & that changes rapidly with electrical items (can come and go fast/randomly) so the coil or the ECU or the pickup could be what is bad but k.i.s.s. since we have changed the coil and ECU several times (at least!) logically as you noted it is time to replace the pickup (or dist). Short version: got another OE dist (or pickup from one) to toss in real quick

nvm.

Was the chrysler lean burn system in effect in 75? or did that come later? just wondering if that could be the issue if this motor in fact has it installed.

I believe '76 on some 440/400 engines