Low voltage

[HiTech6]

Ok guys I need some help. New 200 amp alt. new bat. and still have issue. Car only runs about 12.2 at idle and only gets to about 12.7 until volt booster kicks in and then only gets in the 13.7 range. Should get to about 15 at WOT with volt booster. This makes it hard to tune with the fast as you know. Hot wire to fuel pump coming off alt. Have not checked to see if FP is getting full voltage at WOT yet. I am just not good at electrical and need some ideas on what to check and what to do. Thanks for ANY and ALL thoughts on this.

HiTech6

 

[hiboom]

Are you running the Casper's field fix with this or still using the excite wire from the instrument cluster or maybe not getting a good ground somewhere


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[hiboom]

My 200 amp alternator puts out a consistent 14.4 with no voltage booster


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[HiTech6]

Are you running the Casper's field fix with this or still using the excite wire from the instrument cluster or maybe not getting a good ground somewhere


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hiboom thanks for the reply. I am not running the Casper field fix just a old school volt booster from caspers. At back of Alt. I get 14.4 also. Just have a loss somewhere and not sure where to start to look.

 

[HiTech6]

My 200 amp alternator puts out a consistent 14.4 with no voltage booster


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Just wanted to say your Rosewood car is a real looker.

 

[earlbrown]

Where are you reading the 12.2? Inside the car on something like a scanmaster?


First set your meter on ohms and probe between the engine and the neg post on the battery. It should be practically 0 ohms (or a direct short). Then go from the engine to the body. You need the same result.

Next switch back to volts. You already said you have 14.4 at the back of the alternator.... Verify that voltage again, then move the positive probe to the POS terminal on the battery. If it reads 14.4 you know the charge lead is good. If it's lower, you found the problem.

Next measure the voltage on the orange wire coming off the pos post. Measure it after the connector and the black thing on the wire. If it reads less than 14.4 you found your problem (and you got your 12.2 reading from something the ECM was reporting to)


If all that stuff reads good so far it's time to look at the ignition switch. (not the actual key switch, the switch itself on down the steering column)


pretty sure Steve Wood's VortexBuick site has a how-to on that one.

 

[TurboBuRick]

Earl pretty much covered all the angles. I've also seen the fuse-able links by the starter cause this issue.
Check voltage at the fuse panel. See if any difference between switched power and full time power circuits.

Keep in mind higher amp alternators don't charge much at idle. They need more rpm to energize. Might explain low rpm voltage but it should light up as soon as rpm's come up. Any chance the the belt is slipping?

 

[hiboom]

Just wanted to say your Rosewood car is a real looker.

Thanks, it's my third turbo buick just can't seem to get away from them LOL some one will make a offer i'll sell find another one take it apart fix it and paint it drive a few years .this time i'll think i'll keep this one then look for one to fix up

 

[HiTech6]

Where are you reading the 12.2? Inside the car on something like a scanmaster?


First set your meter on ohms and probe between the engine and the neg post on the battery. It should be practically 0 ohms (or a direct short). Then go from the engine to the body. You need the same result.

Next switch back to volts. You already said you have 14.4 at the back of the alternator.... Verify that voltage again, then move the positive probe to the POS terminal on the battery. If it reads 14.4 you know the charge lead is good. If it's lower, you found the problem.

Next measure the voltage on the orange wire coming off the pos post. Measure it after the connector and the black thing on the wire. If it reads less than 14.4 you found your problem (and you got your 12.2 reading from something the ECM was reporting to)


If all that stuff reads good so far it's time to look at the ignition switch. (not the actual key switch, the switch itself on down the steering column)


pretty sure Steve Wood's VortexBuick site has a how-to on that one.

Great info. Thanks for taking the time to go over this with me. I will get to work on this tonight. You are right I am reading the voltage on my laptop as we were doing a dyno session and the voltage we saw there gave us concern. I pluged in my scanmaster on the way to office this morning and it was reading 12.8 to 13.1. Strange to see different numbers than the FAST showed. I thank you again for your info. This board is awsome!!!

 

[HiTech6]

Earl pretty much covered all the angles. I've also seen the fuse-able links by the starter cause this issue.
Check voltage at the fuse panel. See if any difference between switched power and full time power circuits.

Keep in mind higher amp alternators don't charge much at idle. They need more rpm to energize. Might explain low rpm voltage but it should light up as soon as rpm's come up. Any chance the the belt is slipping?

Thanks and I am going to be checking your recommendations. Thanks for taking time to respond.

 

[earlbrown]

Great info. Thanks for taking the time to go over this with me. I will get to work on this tonight. You are right I am reading the voltage on my laptop as we were doing a dyno session and the voltage we saw there gave us concern. I pluged in my scanmaster on the way to office this morning and it was reading 12.8 to 13.1. Strange to see different numbers than the FAST showed. I thank you again for your info. This board is awsome!!!

Let that one soak in for a little while. When troubeshooting it's VERY important to know when not to trust your tools. Since these cars pretty much run on electricity, it's always good to know your entire electrical system.

 

[bpman1234]

i get the same with the car running 14.volts or better at the alt and the bat and the orange plug after the black thingy .but at the plug of the fuel 13 .4and the ecm scan master read the same 13.4 . it is an old hot wire kit maybe? so then i would have to check the ignition?will look at that vortex now.sorry to hijak alittle

 

[earlbrown]

The low readings back at the tank can be one of two things. Resisted hot lead (doubtful) or resisted ground (more common). I'm betting that wasn't a scientifical test and you moved your ground probe spot.

That being said, when I grounded my frame up front and ran a redundant ground to the frame for the fuel pump, I had to turn my FP down and the car ran smoother and cleaner.

 

[HiTech6]

i get the same with the car running 14.volts or better at the alt and the bat and the orange plug after the black thingy .but at the plug of the fuel 13 .4and the ecm scan master read the same 13.4 . it is an old hot wire kit maybe? so then i would have to check the ignition?will look at that vortex now.sorry to hijak alittle

No problem on the Hijak as I may learn something from your post. Good luck with your issue.

 

[we4Mateo]

The low readings back at the tank can be one of two things. Resisted hot lead (doubtful) or resisted ground (more common). I'm betting that wasn't a scientifical test and you moved your ground probe spot.

That being said, when I grounded my frame up front and ran a redundant ground to the frame for the fuel pump, I had to turn my FP down and the car ran smoother and cleaner.

X2, same results. Grounds are just as important as the hotwire itself.

 

[HiTech6]

X2, same results. Grounds are just as important as the hotwire itself.

Thanks we4Mateo. I am going to add grounds tonight no matter what. Hope to catch you at BG again this year.

 

[bpman1234]

thanks.

 

[Wahoo]

My scanmaster is showing 11.5 volts, I get 12.5 volts at the orange connecter on the battery, to be honest I might have a draw when the car is off or something, so that could be why at the orange plug I only get 12.5, but how do you test the other side of the plug? I can't get the orange wire out of the plug, and i'm affraid I will break it.

I cleaned up the ground on the passanger fender, now I have to find the other grounds and do the same.. my car is a hot air if that makes any difference.

 

[earlbrown]

Sounds like your ignition switch is a little cruddy and not passing full voltage.

 

[bpman1234]

how much voltage is the alternator really putting out .check voltage at alternator positive coming out of the back of the alternator and ground it to the case i think it should be 14 or so volts if its the cs144 case 140 amp at operating temp and put your ac on also at least you will no your starting with go voltage. and when i ran a short battery cable right to the chassie like earl said it made a difference . and i went to the steering column there was an alarm system that was there when i got the car but was not being used and it had a relay cut off. that cut the main wire that came from the ignition switch to the stater .ripped all that stuff out man it looked like spaghetti and i had to solder that main wire back together .my voltage hang around 13 volts.learned allot from the the guys that chimed in . when i was having this issue.