Fuel gauge problem

My dad got a 110 about 3 4 or 5 month ago and the gauge aint ever worked but when he first got it the sender wasnt in properly as found out when first going to put diesel in 10 quids worth poured right out again went to guy he got it from and had it put in right. When back home had a look at it tried the swapping the wires on sender one way is gauge empty other way is guage full. So is there anyway its the sender upsidedown or faulty its meant to be new or the gauge is faulty any help would be great

Tis simply down the wiring, don't assume that it is broken. What you will have to do is put one wire on one terminal and then keep changing the terminals until you get it right. It will be frustrating and it will take a long time because there are a hell of a lot of possibilities! Mine isn't quite right yet!