If your gauge pegs at 3 as soon as the key is in the on position, but the engine isn't running, then that isn't normal.
Likely causes are a bad sending unit or the plug has come of the post at the sending unit, or it could be simply corrosion at the connection to the sending unit. You will find the sending unit on the passenger side of your engine attached to the filter housing. It has asingle lean wire that just pushes on to the post in the center of the unit.
If it pegs as soon as the car starts, then I'd say all is normal.
'73 280SEL 4.5 (9/72)- RIP
Only 8,173 units built from 5/71 thru 11/72
'02 CLK320 Cabriolet - wifey's mid-life crisis
2012 VW Jetta Sportwagon TDI...at least its a diesel
Non illegitemae carborundum.