Fuel Gauge Nuts

[spikeyboi33]

Hey people i have a bit of a problem with my fuel gauge on my 2.0dti.. Thing is when i drive the fuel gauge always acts up. Its a slight movement every now and then but enough to notice it.. For example this morning i drove my dad to work and back.. about 15 miles one way. When i got to his work the fuel gauge went from exactly a half of tank to just a tiny bit below it. Then on my way back home it went another bit which now was a quarter of a fuel gauge section.. (section as in between two markers) and then went straight back up to half a tank again and when i got home it was back to where it was when i was at the workplace.. it does it for some time now and i cant figure it out and its starting to do my head in.. also i only get about 550 miles to a whole tank but i think thats because my thermostat need replacing.

Also i had a problem with my car starting up a few weeks ago. it was due to under-pressurization in the tank and i had to drill a tiny hole in the fuel cap so it would equal out and not give me that problem anymore.

[spikeyboi33]

Anyone?