 electrical system nightmare, alternator is drawing power. |
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| vincesix |
 Sep 17 2005, 10:24 AM
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#1
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Newbie  Group: Members Posts: 38 Joined: 20-December 04 From: Riverside,CA Member No.: 3,313  |
I need some Help. I just completed my 2.7 carburated conversion on my 73 914. The engine is a 2.4 case. I have installed a valleo internally regulated alternator bought from world pac. the b+ lead is connected to the starter battery wire. The d- lead is connected to the ground. The d+ lead is connected to the relay board in the engine compartment lead that goes to the alternator light then to the key switch. The first go with this it was discorverd that the alternator was bad. so A & A alternator in Riverside rebuildt it. When i picked it up they stated that this alternator had been modified from external to internal regulated. After the rebuild I have a dead battery every time the car sits. the D+ lead is hot when every thing is off and now the fule pump runs intermitentlly when every thing is off.
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Replies(1 - 6)
| Joe Bob |
Sep 17 2005, 10:45 AM
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#2
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Retired admin, banned a few times Group: Members Posts: 17,427 Joined: 24-December 02 From: Boulder CO Member No.: 5 Region Association: None |
Test the battery after it's fully charged, at the terminals
12.5 volts at rest 12.5-13.0v at idle 13.0-14.0v max at 2500 rpms any higher and you'll cook the battery. If the charged battery reads low...prolly bad battery. If the battery reads low AFTER looking gud at rest....it could be the alt/regulator.... If it runs on after turning the key off....it prolly has an MSD ignition? Put a diode in the D+ circuit. |
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| Cap'n Krusty |
Sep 17 2005, 10:56 AM
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#3
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Cap'n Krusty Group: Members Posts: 10,794 Joined: 24-June 04 From: Santa Maria, CA Member No.: 2,246 Region Association: Central California |
RTFM! Again, for like the ten thousandth time, the D+ gets its power from the ignition switch THROUGH the pilot light on the dash, the one labeled "G". If it gets power from ANYWHERE ELSE, it's not gonna work right. When the ignition's on, the alternator grounds the circuit and the light is lit. When the key's off, the circuit is dead. When the alternator RPM passes the threshold speed, the ground goes away and the system is charging. If those conditions aren't met, the alternator won't produce current, and the battery may well lose its charge. This is BASIC and FUNDAMENTAL automotive charging system technology, NOT rocket science. The fact that the wire's hot with the key off indicates a fundamental defect in the way the car is wired, or possibly a bad alternator. Disconnect the D+ wire somewhere in the line and see if there's voltage on the side from the switch. If there is, then you have a wiring problem. If not, check the side connected to the alternator. If there's voltage there, the alternator is bad, or there's voltage coming in through a short circuit.
It's been a long time since I got a bad alternator from Bosch (and Worldpac), but they DO offer a warranty on their products, and I've had 35 years of spotty work from a ton of local "rebuilders". Bosch reworks older Bosch, Valeo, and Marelli alternators for internal regulators. That doesn't mean it's automatically a bad thing. Cap'n Krusty out! 10-10, 10-51. |
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| vincesix |
Sep 17 2005, 02:49 PM
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#4
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Newbie Group: Members Posts: 38 Joined: 20-December 04 From: Riverside,CA Member No.: 3,313 |
their is a MSD6A. No one way diode. Will the MSD pull power from the battery and send it through the system draining the battery?
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| Joe Bob |
Sep 17 2005, 02:59 PM
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#5
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Retired admin, banned a few times Group: Members Posts: 17,427 Joined: 24-December 02 From: Boulder CO Member No.: 5 Region Association: None |
Try this.....
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| Joe Bob |
Sep 17 2005, 03:01 PM
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#6
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Retired admin, banned a few times Group: Members Posts: 17,427 Joined: 24-December 02 From: Boulder CO Member No.: 5 Region Association: None |
and this....
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| lapuwali |
Sep 17 2005, 03:23 PM
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#7
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Not another one! Group: Benefactors Posts: 4,526 Joined: 1-March 04 From: San Mateo, CA Member No.: 1,743  |
A nit:
When the alternator is operating, the D+/G light circuit is not "dead". Rather, battery charging voltage is generated there. Since the other side of the G light is ALSO connected to the + side of the battery (through the ignition switch), the voltage ACROSS the G light is 0, so no current flows, so no light. If the alternator is not spinning and the ignition is on, there's only +12 on one side of the bulb (the battery side), so there's +12 across the bulb, so plenty of current flows and the bulb glows brightly. If the D+ wire is hot key off, then, yes, the circuit is wired incorrectly somewhere. |
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