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Discussion Starter · #1 ·
Not only do I have a vacuum leak somewhere, as I am only getting 8.5-9lbs at idle, but I also have a problem with the voltage. I'm assuming some wiring is bad somewhere but the scanmaster is reading in the high 11.0s in volts. Please help me, I already replaced the battery and had the alternator tested. Btw, my alternator says 108 amps and is AC Delco.
 

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Sounds like you need Casper's alternator harness repair kit thinga-majig. :)
You should be seeing around 13.7 and higher at idle and 14+ at WOT.
For $60 or so,it's worth it's weight in gold.
 

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Discussion Starter · #3 ·
Could you post a link? I looked for it on there website. Maybe I'm just dumb but I can't seem to find it.
 

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Discussion Starter · #4 ·
I played with the connections and a volt meter for a little to try to figure things out. I unplugged the grounds that go to the chassis from the negative battery cable to the little screw into the chassis. Still had the underhood bulb on but I figure that's because the black cable was still grounded to the block. Then I unplugged all of the alternator connections. Here's the really weird part. I went from the positive from the battery that connects to the alternator, to the positive connection on the back of the alternator (part you screw + from battery to) and I got 12.6 volts. Shouldn't I get nothing or close to nothing? It was acting like a ground which I thought was weird going from + to +.
 

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Not necessarily...but, normally, it would be like a tenth of a volt, or less if that wire is good.

Hook everything up it should be.

Start the engine. Read the voltage at the alternator. In other words, put the red probe on the back of the alternator and the black probe on the alternator housing or the engine. What does the voltage read? Is it over 13 as it should be when charging? If it is over 13, then move the red probe over to the positive terminal of the battery. Is the voltage showing over 13?

If not, then the problem is wire from the alternator to the battery. It has a connector inside it about a foot from the battery that sometimes goes high resistance.

If there was not 13+ volts at the back of the alternator in the first measurement above, then turn the engine off. Then turn the key back to "run" so the check engine lite is ON. Is the volt light on the left side also ON? If it is not, then your problem is in the dash light circuit. (normally, this is the first thing you check before doing anything :))

Scanmaster voltage being low does not always mean the alternator is not charging, but, can be another problem.
 

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If you unplugged all the alternator connections, then the alternator quit generating. The screw at the back of the alternator would not be "hot", without the alternator turning, and all the wires hooked up, and the light bulb in the dash working.
 

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Discussion Starter · #7 ·
Well if the amps are too low on the alternator could that affect my voltage? What is the recommended amps on the alternator? Mine says 108 on the back. Also, I checked the positive and negative cables and the + is .02 volts and the negative is 0.00 volts. So, they are in good shape I would assume. When I have the car on I am still only getting 12.3 volts to the battery and alternator. When I took the car for a drive the scanmaster dropped voltage from 11.8 (12.3 with voltmeter check) to as low as 11.2. And the droppage usually happens when I give it gas or floor it. Now, I thought the volts would go up when you floor it because the alternator pulley is spinning faster creating more electricity? maybe I'm wrong. Please help.

I also have a post in the turbo section about a vacuum leak if anyone wants to chime in.
 

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Steve Wood said:
Not necessarily...but, normally, it would be like a tenth of a volt, or less if that wire is good.

Hook everything up it should be.

Start the engine. Read the voltage at the alternator. In other words, put the red probe on the back of the alternator and the black probe on the alternator housing or the engine. What does the voltage read? Is it over 13 as it should be when charging? If it is over 13, then move the red probe over to the positive terminal of the battery. Is the voltage showing over 13?

If not, then the problem is wire from the alternator to the battery. It has a connector inside it about a foot from the battery that sometimes goes high resistance.

If there was not 13+ volts at the back of the alternator in the first measurement above, then turn the engine off. Then turn the key back to "run" so the check engine lite is ON. Is the volt light on the left side also ON? If it is not, then your problem is in the dash light circuit. (normally, this is the first thing you check before doing anything :))

Scanmaster voltage being low does not always mean the alternator is not charging, but, can be another problem.
Did you do the above? Is the volt light on when you turn the key to run?
 

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Discussion Starter · #9 · (Edited)
No, the volt light does not come on. Only the brake and fasten seat belt light. Also, the Check Engine Light doesn't show on the dash and never has since I've owned the car. I use the scanmaster to tell me if I have a code. So what do I do now? Is it just a fuse under the dash?

Btw, if you could also help with the check engine light that would be great because I don't know how to get that working.
 

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Let's try to make this very simple and end this problem.

1. You said the alternator tested good.

2. No, the 108 does not mean that is the problem..just means someone replaced the alternator with one that is 12 amps lower in output than the stock original alternator.

3. If the the alternator did test good, then it has to charge if it is getting voltage thru the small brown wire which comes from the dash volt lite.

4. It is getting voltage thru this wire if the dash volt light is burning when you turn the key to run without cranking the engine. If the light is not burning, then you have found the problem.

If you can answer the questions instead of asking other questions, then we can get somewhere. :)
 

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Discussion Starter · #11 ·
Okay, so the alternator is not getting voltage because the volt light is not showing. So, what do I do to make the volt light come on when I turn the key?
 

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I fixed my alternator 4 years ago by wiggling the volt light bulb in its socket.
 

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Discussion Starter · #13 ·
Yup, replaced the bulb and all is well now. Thank god. But now that the battery is funcioning properly I all of a sudden have a Malfuncion 31 code and fuel pressure is not rising above 36psi under throttle. Can't get it above 36 psi either.
 

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2. No, the 108 does not mean that is the problem..just means someone replaced the alternator with one that is 12 amps lower in output than the stock original alternator.

That may be the case but sometimes they are rebuilt as 120 amp (or higher) but they sometimes use the 108 core. So the 108 is not necessarily 108. :)
 
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