02Reaper

iTrader: (2)

just had the underdrive crank pulley taken off of the truck (2002). The next morning when I crank my truck up, everything is normal, then the dash lights and headlights start flickering, the voltage guage is moving up and down also with all of this but nothing is undercharging. I drive to work and when the truck warms up the flickering stops and everything is normal. The next morning the same exact thing happens, so I take it to the chevrolet place, but by the time I get there it has stopped. They check the battery and alternator with the machine and everything checks out, alternator is putting out 14.7 volts. So the next morning before I crank the truck up I hook a voltmeter to the battery and it reads 12.5 volts, truck cranks fine and same thing happens again. SO I go to the parts place and get a new alternator, put it on and in the morning guess what? it does it again, just till it warms up everytime. I get home in the afternoon and check every ground and cable and nothing is out of place or dirty (took it all apart and checked) All of this happens when the truck has set for probably 8 hours or so. It has been in the 30's to 50's temp wise. ALso got a new belt that doesnt help either. Does anyone know what the problem could be, I am stumped

onyx

ok...i may be way off on this... but, doesnt the underdrive pulleys attach to the fan clutch? ... i'm not sure if they do... but if they do, maybe the clutch was used to the size of the aftermarket pulley and is somehow not working properly until it has hit a certain speed with the oem pulley back on... because doesnt the aftermarket pulley cause some voltage issues... i would figure your PCM might have to get used to it...

i'm probably way off, and delirious from being stuck in this hole for so long... but hey.. anything is worth a try i suppose.... :/

02Reaper

iTrader: (2)

The truck did not have a problem charging with the ud crank pulley on, that is all that I installed. It has also been going on for about 2 weeks now, so I think the computer would have adjusted by now. Thanks

mudz5.3

The ud crank won't cause charging problems, additionally with the altenator underdrive pulley will. You have a weird problem and sorry I can't help. I posted up a week or two ago about a prob with low fuel level, heater/ac not working. I thought it was fuel related, but it did it again this morning and I had a 1/4 tank. So looks like the cooler weather brings the bugs out in our trucks.