Fuel sending unit replace

I installed a spectra unit, would not recommend, it "works" as
you can tell there is gas in the tank . Accurate hell no. I would
start by checking the wiring and gauge, ground the wire to chassis for a few seconds should sent fuel gauge past full or install
a 10 0hm resistor between the sending unit wire and chassis
grounds with alligator clips and read the gauge should read to
the full mark.
If this test passes then remove the sending unit and examine
it for damage especially the wire wound resistor, If it looks
OK, I would clean the sending unit in a ultra sonic bath. My
local small engine repair shop has one used to clean carbs an
small parts they may help you out.