98 GMC Z71 questions

[Threadzy]

My son just purchased this truck. His first vehicle. Two questions. The transmission shift good until you smash the throttle. You have to let off slightly for it to shift. Is there an adjustment some where on the transmission or a bad solenoid possibly?  Next question. When you first turn the key on the fuel gauge pegs back and forth a few times real fast then stays at empty. Is this a bad gauge or sending unit? 

[Mopar1973Man]

Change the filter inside the pan. Ive just talked to a friend few days ago that had shift issues and slightly higher trand temps. Changed the internal filter and fluid and problems are gone.

[Threadzy]

Thanks Mike! Any thoughts on the fuel gauge? 

Edited July 9, 2021 by Threadzy

[Mopar1973Man]

Most likely a bad sender. Check error codes it might confirm this. Fuel gauge error most likely will not set check engine light.