Gas gage

New vehicle for us... '82 240D with a gas gage that reads 1/3 when empty. Will stay on full for first 180 miles. Seems consistant. Is this a matter of bending the tank float or an electric adjustment? How do I access the float?

Running out gave me a reason to replace the leaky primer pump with the new improved non screw-in type. and I'm thankful for that $20. upgrade. But short of using the trip odometer and a pessimistic guess on MPG this could lead to some agravating moments.

Thanks for the assist.

Jeff