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zzark
Gen II
12/05/2005
08:13:00
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 Subject: ASP underdrive = dim lights ??
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Message:
New underdrive Crank pulley on a 3.9 is causing charging problems. I have only the crank, not the other underdrives. New belt too.
Does that indicate I need a new alternator?
I also installed an electric fan and it draws 13 amps. When it runs, the battery gauge goes way down, to abut 10.
Thanks
zzark
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cuzindoug
GenIII
12/05/2005
09:07:40
| RE: ASP underdrive = dim lights ??
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Message:
With the underdrive pulley, you will be spinning the alt at a lower speed. No you don't need a new alt necessarily, but you will need a different pulley for the alt to increase the speed.
If it ain't broke, fix it til it is.
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daddio
Dodge Dakota
JOIN HERE
12/05/2005
09:16:43
| RE: ASP underdrive = dim lights ??
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Message:
you may want to check your alternator but i would start by looking at the connections on your fan.
for instance, Where are you tapping in for 12+ for the fan? How about the ground wire? What size wire did you use.
i have had an underdrive pulley on my '00 QC for almost 2 yrs. haven't had any problems at all. and i still have the original (6yr old)battery.
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cuzindoug
GenIII
12/05/2005
13:52:46
| RE: ASP underdrive = dim lights ??
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Message:
Depending on what "ratio" pulley you bought it may or may not affect charging.
If it ain't broke, fix it til it is.
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zzark
Gen II
12/05/2005
20:47:45
| RE: ASP underdrive = dim lights ??
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Message:
It is a 25% reduction.
Fan installed per the instruction. The wires are heavy duty. 12 volt is a 12 gauge. One 12v to the battery, another 12v to a 30 amp circuit at the underdash fusebox.
If it stops RAINING, I'll go to Advance and get a battery and alternator checkup.
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Branson
Dodge Dakota
JOIN HERE
12/05/2005
21:21:24
| RE: ASP underdrive = dim lights ??
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Message:
25%?
That means you need to turn your engine at 1000rpm to get the same charge rate you used to get at a 750rpm idle.
Don't underdrive the alternator. Bad things will start to happen to your computer (controls alternator charge rate, so it could be trying harder to charge the battery now, which might overstress the circuitry that does this), injectors may not get the voltage they need to pass gas properly ay idle, spark plugs voltage may be reduced, and yes the lights will dim on you as you suck all those trons out of the battery.
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daddio
Dodge Dakota
JOIN HERE
12/06/2005
09:06:14
| RE: ASP underdrive = dim lights ??
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Message:
i think you'd be better off with 10 or 8 gage wire. my 300watt amp has an 8 gage + and 10 gage ground and it doesn't draw as much as that fan does.
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kaderdak
GenIII
12/06/2005
18:49:06
| RE: ASP underdrive = dim lights ??
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Message:
I had a set of march pulleys on that included: crank, water pump, and alternator. I had so low of a charge the engine almost died a few times. Put the original alternator pulley back on, but left the march crank and water pump pulley on and has been fine since. So, I think you should be fine with just a crank pulley.
** '97 Dakota 5.2L 4x4 w/3.55(my best ebay purchase yet) **
** Homebrew CIA, Dynomax Catback, March Underdrive Pulleys, Transgo Kit **
** Borg Warner Brass Cap/Rotor to Taylor 8mm wires to NGK plugs **
** Homebrew dual electric fan setup with 180* thermostat **
** Sitting on BFG 31 x 10.50's **
** Tons more once I'm not a poor college student :) **
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