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post #1 of (permalink) Old 01-07-2006, 10:57 PM Thread Starter
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elec problems...

my issue is with my 77' j-10 w/258,(stock, except for jacobs ignition, weber carb). the lights seemed dim and the voltmeter would stay down in the red and would only get to 12 volts if you pushed in the clutch and reved the engine. took it to advanced auto, they hooked it to the machine and said the alt was bad. so i replaced it. when i started it, the volts were about 12. but when i started to drive it, the volts went to about 14, and lights were BRIGHT. then engine cut out for just for a second, but when it came back, volts stayed at 12 and started to smell (elec) hot. pulled over found nothing. continued to drive it, voltage now goes to 14, lights are BRIGHT and the elec fuel pump sounds like it is screaming. so only thing i can think of is that it is the voltage regulator. alt was a straight swap, 1 wire bolted, 2 spade connectors.

anyone have any thoughts?

thanks all
shawn
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post #2 of (permalink) Old 01-08-2006, 07:46 AM
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Re: elec problems...

My guess would be a poor connection between the alternator output lug and the battery, but could also be a poor ground connection between the alternator case and the engine block. When the connection fails you have 12 volts in the system, or a bit less. When the connection is good you have 14 volts, as you should, and the lights go bright and fuel pump runs at full speed.

It explains everything but the hot electrical smell. That could be from the heater fan resistor getting hot and smelling from having full voltage for the first time in a long time.

The other possibility is that somewhere in the system is an intermittent short that is drawing lots of current and heating up. That's unlikely because by now it would have blown a fuse or burned up something.
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post #3 of (permalink) Old 01-08-2006, 10:23 AM
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Re: elec problems...

Check/refurbish/clean the main grounds.
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post #4 of (permalink) Old 01-08-2006, 03:38 PM
 
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Re: elec problems...



First off, you may not know what the fuel pump or anything else is supposed to sound like if your old alternator was 'lacking' for a long period of time...

Time to go back to Advance Auto when the thing is making 14 or more volts.

Sounds like the alternator is trying to go full field, and this will cause problems.
If you are showing anything under 14 volts, you should be fine.
Anything over 14 volts is murder on the battery.

Anything over 16 volts will kill your Jacobs ignition module, so keep that in mind when you jump start anybody...
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post #5 of (permalink) Old 01-09-2006, 02:56 PM Thread Starter
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Re: elec problems...

yeah, the poor truck probably hasn't seen full voltage for a very long time. also, when installing the new alt. i didn't disconnect the battery (i'm lazy) and when i touched the new alt (with all the wires connected) to the bracket, it sparked between the alt and bracket. so does this mean that it isn't grounded well or there is a draw somewhere?

thanks
shawn
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post #6 of (permalink) Old 01-10-2006, 06:54 AM
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Re: elec problems...

Big spark or little spark? Did it do it several times or only the first time you touched? If the ignition switch was off there shouldn't be any spark.
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post #7 of (permalink) Old 01-10-2006, 11:27 AM Thread Starter
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Re: elec problems...

little spark. it happened several times. so what does that point to? i do know that the ground needs replaced, and is the next step. (i already bought it months ago and just haven't thrown it on)

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post #8 of (permalink) Old 01-10-2006, 12:10 PM
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Re: elec problems...

Normally the alternator is grounded through the bracket unless it has a separate ground wire. The bracket is usualy enough unless you've had it powder coated or heavily painted.
The critical ground is between the engine to the body - make sure that ground is good.
A remote regulator uses body ground, where the alternator uses the engine ground -- THEY MUST BE THE SAME.
Two engine to body grounds cannot hurt.

Connecting everything with the battery still connected is asking for trouble - just like you have now.

ALWAYS disconnect the battery when fooling with the alternator.

The little spark to ground - that shows something in the alternator is defective - like maybe a shorted diode or diode trio. It should not have sparked.
The burned smell verifies it.

I'd take it to where you had it tested before - test it.
Get a good one - test it before you take it home!

Then when installing it - MAKE SURE THE BATTERY IS DISCONNECTED FIRST!

Let us know how it turns out.
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post #9 of (permalink) Old 01-10-2006, 10:14 PM Thread Starter
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Re: elec problems...

i bought the alt from advance auto for $35. i seem to have about 10 or 20% of the stuff i buy there be defective. you get what you pay for. i'll keep you posted.

thanks all
shawn
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post #10 of (permalink) Old 01-11-2006, 05:45 AM
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Re: elec problems...

NAPA....you pay a little more, but replace it a LOT less.
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