fuel and temp guage

[zxtrevr]

got a couple of little problems
1 . the temp guage doesn't work at all.
2 . the fuel guage is a bit dodgy sometimes it'll be fine then you would go round a corner then it'll go into the red then come back up but it doesn't go right down empty.

just wondering where to start
94 audi 80 2.0 8v (B4 i think, my first Audi)

thanks Trev.