Does it ever read full? ...sounds like the sending unit. Remove it, hook the wiring back (away from any fumes), and see what the gauge reads as you travel the float (assuming it's the older float style). If all works, the sending unit needs adjusting which probably means bending the float arm down.

Of course it could be wrong unit as the float must be able to travel the height of the tank.

...hope it's the sender, they're cheaper

well I know this sounds redneck but the live-in girl friend has a bbf jet boat 460 ford 2 fours tunnel ram and never had a gas guage drove me nuts when we were out ,we just checked it every no & then with a cut off wooden dowel rod sounds funny but it works.. just stick it in the tank look at the wet spot make a mark when full.

hi all;
i have a 30 gallon tank and when i have 1/4 tank of fuel left on the guage and i fill it i can barely get 8 gallons into the boat. is there some way to make my sensor more accurate? im thinking the sensor might be too short for my tank. it's a pain to still have so much fuel but have no clue how much is left. the boat is an 04 hydrostream voyager. wordering if anyone else with a newer voyager has the same problem with their guage? . the boat has NORDSKOG guages.

any help is much appreciated