electrical problem?

got a 97 park ave from auction the other day,got it started and it is not reading fuel and/or temp on the dash. the guages are the needle style. when starting the car the gas hand goes up past full then back down to under empty mark. i am able to read temp on scanner though. i need some ideas as to what to look for to decide whether to fix or not.

I use a scangauge II to monitor my fuel use and temperature.