yeah. u must have pull the needle out when u were removing those face plates.
ur not suppose to. i'm pretty sure ur speedo is off too if u took the needle off of that. the rpm finds its way around usually.

i think the only thing you can do right now is go to a junk yard and get a different gas guage.

theres a way to adjust the speedo. if urs is not working right let me know. i'll tell you how to fix it (get it close)