Fuel gauge reads full all the time?

[Herewego]

I just replaced the fuel tank sending unit because fuel gauge gave eratic readings. I wired the pink wire to positive on senting unit and black to ground tank reads full all the time. I switch wires around black to pink and pink to ground and gauge still reads full. Is it bad gauge or what?

[CJseven]

The pink wire should be the one coming from the gauge, if so unhook it from the sending unit and see if the gauge falls to empty if so the sending unit is grounding out if the gauge still reads full than the wire from the gauge to the sending unit may have a short somewhere or the gauge itself maybe bad. Also use a Ohm meter to check the resistance of the sending unit from empty to full.

[Hogster1]

Ditto:D

[Herewego]

Thanks CJ
I Unhooked the pink sending unit wire and gauge went to empty. There are only 2 wires, pink and black.

Should I remove sending unit and check with ohm meter and replace 2 wires to gauge?

[CJseven]

I just reread your last response , I don't see a reason to replace the wires if the gauge fell back to empty by just removing the pink wire from the sending unit, sounds as if it's fine. If I am thinking right you should have one wire going to the gauge that is hot with the key and the other wire is the one that goes to the sending unit, and basically acts as a ground sort of speak. The better the ground the higher the gauge will read. You may have the wrong sending unit for your gauge. If you have the model number and brand of gauge then you can find out what Ohm range it is, and match it up with a sending unit.

[Herewego]

I check new sending unit with ohm meter verses old sending unit. New unit was 33 with float at top, 166 float at bottom. Old unit 31 float at top but erractic numbers at bottom. I replaced sending unit and ground wire.

Note: Old SU was plastic, new SU is stainless steel.

Gauge still reads full with both units. Is it the gauge? If so, how do I order correct gauge?
Thanks

[old fuzzy]

what is this in or used in,,?

[Barnacle Bill]

Typical fuel gage wiring:

[Herewego]

what is this in or used in,,?

CC Bay Boat with aluminum tank.

[Herewego]

Typical fuel gage wiring:

Boat is wired to diagram on left, SU has a vertical slider float.