:mad: Man Im getting sick of this! Started truck today fuel guage goes to full! About 5 minutes later redlight is on and guage reads empty! 2 weeks ago the dealer replaces the sending unit and transfer pump! They also told me they are havins a software problem with the 05sfuel guage system and there is no fix yet ! I mean this sucks trucks got 755 miles and its been in 4 times already!
Anyone having this problem, or any service reps heard of this? After its reflashed its ok for a day or 2!

The only problem I have is after about 430 miles, my gauge reads empty...

Sounds kinda like a grounding problem to me. If the gage circuit has a floating ground it could possible act like you describe.

Mine has done this once. It was around 1/4 then dropped to E and started telling me about low fuel. I stopped and started and it went back to 1/4. I have 6,500 miles, only happend once so far. Hope it works out for you.

I got a 2004.5 and it's been in the shop 16 time for the same thing..

Two things could be happening:
1) the fuel sender circuit has a bad ground- find the schematic, trace the ground and clean/tighten it.
2) the fuel sender goes above "true full" (about 98%) and the pcm sees it as a failure in the sensor, responding by taking the gauge to empty and setting a code.
Do you have a SES light on?
I have no experience with the two tank system, so I may be out in left field somewhere...:confused:
Hope this helps
Ed

I drove mine for a week, then ran out of fuel.:o :mad: Gauge still read almost full. Guess I thought I was still driving the 2003 with the long bed and big tank. Wife had a nice comment when she had to pull truck home with her 1997 D*dge gasser (the 'little' truck). Took in for service - replaced sender. New one stayed on 'E' :mad: :mad: . Truck was supposed to go into storage, but had to go back to dealer, again. Total miles since purchase 11/30/2004 - under 800. I hope it is fixed now, but only drove it home to put in storage for the winter. I will be even more :mad: if it does not work when I get it out for spring break trip south towing the trailer.

Well After the 5th trip same story! Code is for low Fuel rail pressure and every thing checks OK! After reflash its normal! After talking to GM they say they know there is a software problem and hope to have a fix for it soon! He said it affects 04.5 and 05 Trucks. So dont believe that Guage count your miles!