Fuel Guage misreading after new pump fitted

Can anyone advise me.?

I fitted a new pump to my Disco 2.

Filled up the tank. Usually I get 600 miles to a tank. ( diesel )

I got to 130 miles and guage was showing HALF TANK !!!

So thought it odd and went to fill it again. But right amount of fuel went in for less than 1/4 tank used.

Is there any way to calibrate a new unit ?

It drops very fast on the first quarter then half.

Cheers,

Dons x

If you didnt buy genuine then thats a common fault. i put a bearmach in mine 40 lts of diesel and within 5 miles fuel light came on.i swapped the fuel sender and float over from my original pump dead easy .