Fuel Gauge making full, even with no power.

[MaxGlide]

So fuel sending unit failed. Replaced with new. Now fuel gauge reads FULL, past the full line, all the time, even with power completely off. Not just key, power off at battery switch.
I can’t seem to find info online for causes.
Thanks in advance for any help.
Wayne.

 

[MaxGlide]

ADDED INFO. Before getting new sender, I "tested" the console gauge by running a wire between the ground wire and the sender wire at the sending unit, Gauge jumped to full then back down when I removed connection. Could I have fried the fuel gauge at the console?

 

[04fxdwgi25]

ADDED INFO. Before getting new sender, I "tested" the console gauge by running a wire between the ground wire and the sender wire at the sending unit, Gauge jumped to full then back down when I removed connection. Could I have fried the fuel gauge at the console?

Probably. The gauge sender minimum resistance is 33 ohms (240-33), 33 ohms being FULL and 240 empty. Grounding it, dropped the 33 to zero. You effectively shorted it out and smoked the gauge.

 

[brodmann]

The gauge is actually an ohm meter. Yeah, you fried it. Best way to test the sending unit is with an ohm meter. Don't buy a cheap gauge off of Amazon. The really cheap ones work backwards!! My son has one installed on his boat. Also, the sending uinit should have the ohm range stamped on it. They're not all the same.

 

[Scott Danforth]

check the resistance of the pink wire from the sender to the gauge.
check the resistance of the sender
doubt you "fried" the gauge.

 

[MaxGlide]

UPDATE
So the fuel gauge dropped back down when I tapped it (with power completely off, not just key). Needle was stuck. HOWEVER… now this is the problem. As soon as I turn battery power on (key still off), the fuel gauge goes to the max. Now the bilge pump and wiper don’t work and the fuel and temp gauge are pinned.
I am thinking there must be a short somwhere. I should add that there is one post where a bunch of things are grounded to. I installed a buss bar a few years ago to ground some other things. I’m thinking it must be a short where in an area common to those instruments. It’s like one half if the panel is affected. Picture shows which instruments are affected, I’m going to see if these have something in common as fas as wiring goes.

 

[dingbat]

UPDATE
So the fuel gauge dropped back down when I tapped it (with power completely off, not just key). Needle was stuck. HOWEVER… now this is the problem. As soon as I turn battery power on (key still off), the fuel gauge goes to the max. Now the bilge pump and wiper don’t work and the fuel and temp gauge are pinned.
I am thinking there must be a short somwhere. I should add that there is one post where a bunch of things are grounded to. I installed a buss bar a few years ago to ground some other things. I’m thinking it must be a short where in an area common to those instruments. It’s like one half if the panel is affected. Picture shows which instruments are affected, I’m going to see if these have something in common as fas as wiring goes.

Does not sound like a ground problem. You have a short to ground somewhere.

Since the bilge pump no longer works, I would start there. They are notorious for leaking current to ground upon failure

 

[MaxGlide]

Does not sound like a ground problem. You have a short to ground somewhere.

Since the bilge pump no longer works, I would start there. They are notorious for leaking current to ground upon failure

Sorry, I meant a short to ground. I was poking around behind the consloe, moving wires around. I must created a short somewhere.

 

[dingbat]

Sorry, I meant a short to ground. I was poking around behind the consloe, moving wires around. I must created a short somewhere.

A "true" short to ground should have tripped a breaker or blown a fuse.
More the symptoms of a current leak.

Are you sure the sending unit is wired correctly?
I have installed a couple of senders didn't match conventional color.

Pink wire went to ground and black wire went to the sender

 

[MaxGlide]

UPDATE
Turns out the gauge part was a loose ground behind the fuel gauge. Also, initially, the gauge needle was stuck all the way forward and I tapped it and it went back down.
The wiper and bilge pump was me mucking around back there, in the dark, and disconnected wires by accident. Got back there with a good light and some tools, tightened here and there, hooked wires back up and PRESTO, all is working.
The original sending unit was pooched though.

Thanks all for your help! With various tips and suggestions, I got it done!

Wayne