electrical problems, overcharging, ignition issues

[MO roadrunner]

Have a 1970 roadrunner with 383 that's giving me fits, started out with ignition problems, wants to stall out when warm, wouldn't start. Replaced ballast resister and it fired right up . Did some checking and found out it's charging 19 volts. I've checked all grounds, replaced VR and had alt checked and it failed test so I replaced alternator. Down to 16.25 volts. Clean connections at firewall, no change. battery checks out good. I checked my meter against another meter and my meter is reading 1 volt higher, so I'm thinking my meter might be faulty. Still my ballast resister is burning hot, like you can't touch it or you will burn your fingers. I 'm thinking all these issues are connected some how, but I can't find the problem. Any help would be appreciated , haven't driven car much this summer since if I get about 15 miles from home it starts to screw up and I end up going back home so I don't get stranded. Would like to hit a few car shows this fall if I can get this problem solved. Again, thanks for any help

 

[Don Frelier]

If it's running at 15 volts or over then I would suspect the voltage regulator.
Particularly if it's the old mechanical "Points" style they may be welded shut and giving you full charge.

 

[Nacho-RT74]

19 volts doesn’t mean is allways overcharging. Sure something is going wrong AND TIPICALLY could be an overcharge deal, but doesn’t mean automatically is even (over)charging. Once I was getting up to 24 volts opening throttles at batt but discharge on ammeter. One of the stator leads reaching the diodes bank was getting in touch with some of the rotor cooling vanes at every spin. That was causing the fail being a pulsating short.

Ballast has nothing to do with charging system, just ignition, even thought both are sourced from same network. Yes they get REALLY HOT.

 

[pnora]

Have a 1970 roadrunner with 383 that's giving me fits, started out with ignition problems, wants to stall out when warm, wouldn't start. Replaced ballast resister and it fired right up . Did some checking and found out it's charging 19 volts. I've checked all grounds, replaced VR and had alt checked and it failed test so I replaced alternator. Down to 16.25 volts. Clean connections at firewall, no change. battery checks out good. I checked my meter against another meter and my meter is reading 1 volt higher, so I'm thinking my meter might be faulty. Still my ballast resister is burning hot, like you can't touch it or you will burn your fingers. I 'm thinking all these issues are connected some how, but I can't find the problem. Any help would be appreciated , haven't driven car much this summer since if I get about 15 miles from home it starts to screw up and I end up going back home so I don't get stranded. Would like to hit a few car shows this fall if I can get this problem solved. Again, thanks for any help

Very common problem is the voltage regulator plug being bad. If the regulator does not see the current battery voltage it will overcharge. Seeing the current state of battery voltage is how the regulator controls the charge rate of aprox. 13.8-14.2

 

[MO roadrunner]

It's a new reproduction wiring harness from Classic Industries installed within the last 2 years, but I will check it, I had a wire pull out of the plug on the ballast resister , was poorly crimped, replaced it with a new connector. I guess new doesn't always mean your troubles are fixed. thanks

 

[MO roadrunner]

If it's running at 15 volts or over then I would suspect the voltage regulator.
Particularly if it's the old mechanical "Points" style they may be welded shut and giving you full charge.

It's been converted to electronic years ago, just started giving me problems this spring

 

[hunt2elk]

After checking to be sure everything is grounded good, you need to measure the voltage drop across every connection. I had a bad ignition switch a couple years ago causing high voltage. And probably wouldn't be a bad idea to buy a new multimeter so you know exactly what is going on.

 

[RJRENTON]

If it's running at 15 volts or over then I would suspect the voltage regulator.
Particularly if it's the old mechanical "Points" style they may be welded shut and giving you full charge.

If its the old mechanical voltage regulator (not likely as it's a '70 vehicle), and the upper regulator poihts weld together, the alternator will charge it's maximum, then the fuse element, internal to the regulator opens, and the alternator stops charging. The electronic voltage regulator's (standard on '70 vehicles) internal switching transistor may be damaged (shorted) causing the alternator to charge at MAXIMUM. Consider disconnecting the green field wire at the alternator....it charging continues, the brush ssembly may be grounded, causing the alternator to charge at MAXIMUM.......just my thoughts......
BOB RENTON

 

[MO roadrunner]

Believe problem is fixed, new VR, Alternator, bought some heavy duty braided copper cable and made ground straps for VR and ECU, cleaned bulkhead connectors. Also got a newer meter. Just got back from a test drive and everything seems to be working as it should. Want to thank everyone for their help.