What could a bad regulator potenially destroy?

[Lars]

My 73 won't start (crank but not start), I'm not getting any spark while it's cranking. I checked out the ignition unit, ballast resistor, and the voltage regulator. I bought all three new and compared the measurements. The regulator was bad and so was the ignition unit. I replaced them and the ballast resistor, but the car still won't start (no spark). I checked the resistance on the reluctor in the distributor and it measured 300 ohms which I think is OK. The only other thing I can think of is the coil went bad, but I thought they usually acted up when they got warm. The ammeter isn't in the circuit anymore because I bypassed it. So as of right now I'm out of ideas. If it isn't the coil, what else is left?

Thanks

 

[dgc333]

I would make sure you are getting power to everything in the ignition. In the run position you should have 6-8 volts at the + on the coil and in the crank position you should have battery voltage. You need battery voltage to the ecu, forget which pin, in both run and crank positions. The ecu also needs a good solid ground, I run a ground strap from the ecu to the block to make sure. If you have a 5 pin ecu you need the dual ballast with four connections, 4 pin ecu only needs the two pin ballast. If you have a two pin ballast is it plugged into the correct terminals on the connector?

Have you checked the air gap on the pickup, it should be 0.008", if its to wide the reluctor won't generate a voltage pulse.

The coil should have approximately 1 ohm of resistance on the primary and 5000 on the secondary.

Have you verified that the distributor is turning when you crank the engine? Broken timing chain, cam of improperly seated distributor will keep it from turning.

Pull the distributor and put a volt meter (low voltage range) across the magnetic pick up leads and spin the distributor, you should see a voltage pulse.

This is about all the things I can think of off hand to check.

 

[Lars]

It's a 4 pin, and I switched to the two pin ballast resistor. I measured from the coil to the harness to see which one was supposed to be connected. I was having this problem a few weeks ago with the car. I replaced the ECU with the one off my truck (put a new on on the truck), and it ran fine for a few days and now it's dead again. The ignition module (ECU) measured bad again so I figured something burned it up, that's why I checked out the voltage regulator. I'll have to check to see if the coil is getting voltage or not while its cranking. The air gap should be OK, I haven't ever messed with it and I don't see how it could have changed. I'll measure across it while cranking though because I know they can go bad (it measured 300 ohms sitting still).

 

[Lars]

I would make sure you are getting power to everything in the ignition. In the run position you should have 6-8 volts at the + on the coil and in the crank position you should have battery voltage. You need battery voltage to the ecu, forget which pin, in both run and crank positions. The ecu also needs a good solid ground, I run a ground strap from the ecu to the block to make sure. If you have a 5 pin ecu you need the dual ballast with four connections, 4 pin ecu only needs the two pin ballast. If you have a two pin ballast is it plugged into the correct terminals on the connector?

Have you checked the air gap on the pickup, it should be 0.008", if its to wide the reluctor won't generate a voltage pulse.

The coil should have approximately 1 ohm of resistance on the primary and 5000 on the secondary.

Have you verified that the distributor is turning when you crank the engine? Broken timing chain, cam of improperly seated distributor will keep it from turning.

Pull the distributor and put a volt meter (low voltage range) across the magnetic pick up leads and spin the distributor, you should see a voltage pulse.

This is about all the things I can think of off hand to check.

Went out with the DMM today to see what the coil was seeing, and it is getting 6.19 volts in the run position, and about 7 volts while cranking. Figure this though, while I was checking it the car started. The wiring harness on that side of the car that feeds the coil, alt, and other stuff is all burned up (was like this when I got the car three years ago). Last time I messed with the car (when it was deader then a doornail) I went over there and tugged around on it, pushed the connector together (whats left of it), and wiggled it around. I didn't try to start it again after that though until today. So I'm thinking its a short/open in that section of the harness.

 

[pushrod]

I feel your pain. I finally had to order anew engine harness for my 70/340 Dart today. It had been cut so many times we gave up. I have an electronic dist. to install so I just order the one with all the wiring built in.

 

[Lars]

Well I bypassed the burnt plug and soldered everything direct. Hopefully this fixes it permanently. Currently it is still starting and running, I took the opportunity to ditch some unused vacuum lines and hardware that was just cluttering up the engine bay.