Voltage Dropping-any ideas?
10-31-2007, 09:26 PM
#1
Staging Lane
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Voltage Dropping-any ideas?
Hey Guys,
I have a voltage dropping issue that maybe causing another problem. When i am out running through the gears at full throttle the volts begin to drop from 14.0 at say 5000 rpm,12.0 volts at 6000 rpm. When the truck shifts at 6000 rpm and drops down to say 3800 rpm the volts return to 14.0 unit it reaches 5000 rpm again. At the same my fuel pressure drops from 55 psi down to 30-35 psi and the air/fuel ratio climbs into the 13-15 range. I wonder if the drop in volts is enough to effect the volts to the pump to cause fuel pressure to drop or do i need more fuel pump? Should i try a bigger pump first and hope the volts are enough to run it or should i fix the volt issue first,knowing i will need a bigger pump regardless.
Speed Freak
I have a voltage dropping issue that maybe causing another problem. When i am out running through the gears at full throttle the volts begin to drop from 14.0 at say 5000 rpm,12.0 volts at 6000 rpm. When the truck shifts at 6000 rpm and drops down to say 3800 rpm the volts return to 14.0 unit it reaches 5000 rpm again. At the same my fuel pressure drops from 55 psi down to 30-35 psi and the air/fuel ratio climbs into the 13-15 range. I wonder if the drop in volts is enough to effect the volts to the pump to cause fuel pressure to drop or do i need more fuel pump? Should i try a bigger pump first and hope the volts are enough to run it or should i fix the volt issue first,knowing i will need a bigger pump regardless.
Speed Freak
Last edited by SpdFrk; 12-30-2007 at 09:06 AM. Reason: new information
12-30-2007, 09:59 AM
#3
yes, the voltage drop directly effects any electrical motor. You have fueling tables in the pcm that will fatten your inj's (lamens explanation) when the voltage goes down but it can only do so much. That fuel pump is definitely pumping less.
Stop by a local auto parts place and ask to have your alt tested. Sounds like when you rev the alt up it starts to fail. I see in you sig you have the 145 alt with a larger pulley, over drive crank pulley. Re-do the math and make sure that alt isn't being over spun as well.
Stop by a local auto parts place and ask to have your alt tested. Sounds like when you rev the alt up it starts to fail. I see in you sig you have the 145 alt with a larger pulley, over drive crank pulley. Re-do the math and make sure that alt isn't being over spun as well.
12-30-2007, 10:16 AM
#4
Stop by a local auto parts place and ask to have your alt tested. Sounds like when you rev the alt up it starts to fail. I see in you sig you have the 145 alt with a larger pulley, over drive crank pulley. Re-do the math and make sure that alt isn't being over spun as well.
12-30-2007, 12:20 PM
#5
Staging Lane
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as far as the alternator this is the 4th 145 amp on this motor. the first 2 started squealing so i replaced them, the 3rd i put on a asp underdrive pulley on it and as soon has you would start turning any rpm the dtc would say battery not charging and the volt gauge was reading 9 volts so it didn't like that so on the 4th i decided i would try a slighty bigger pulley and see if that would work but it not change still starts at 14 and drops to 12. is there such a thing as using a LS6 alternator since that motor turns more rpm? What about a Casper Voltage Booster? do they work on our trucks?
12-30-2007, 12:39 PM
#7
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BlownChevy,
I am running a stock AC Delco 145 amp alt. I have tried it with the stock alt pulley but it still does the same thing. Do u thing a bigger battery would make any difference? I would almost thing there is something else causing this problem if u can run the same alt at 6600 and i am sure we are not the only guys running a blown gen 3 with 145 amp alt. Could a weak ground be the problem?
I am running a stock AC Delco 145 amp alt. I have tried it with the stock alt pulley but it still does the same thing. Do u thing a bigger battery would make any difference? I would almost thing there is something else causing this problem if u can run the same alt at 6600 and i am sure we are not the only guys running a blown gen 3 with 145 amp alt. Could a weak ground be the problem?
Last edited by SpdFrk; 12-30-2007 at 12:41 PM. Reason: new info
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12-30-2007, 12:40 PM
#8
BlownChevy,
I am running a stock AC Delco 145 amp alt. I have tried it with the stock alt pulley but it still does the same thing. Do u thing a bigger battery would make any difference? I would almost thing there is something else causing this problem if u can run the same alt at 6600 and i am sure we are not the only guys running a blown gen 3 with 145 amp alt.
I am running a stock AC Delco 145 amp alt. I have tried it with the stock alt pulley but it still does the same thing. Do u thing a bigger battery would make any difference? I would almost thing there is something else causing this problem if u can run the same alt at 6600 and i am sure we are not the only guys running a blown gen 3 with 145 amp alt.
12-30-2007, 12:44 PM
#9
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not sure on the belt tension, i don't think it's to tight. if it was any looser wouldn't i then have to worry about belt slip on both the alt and blower?
