Fuel Gauge always showing Empty on both tanks

[WMFisher]

I have a 2011 Puma FTD with a SHO and NEXSys Link Gauges. Everything has been working great, but last weekend, my fuel gauge stopped working from the jump. Trying to troubleshoot, but haven't nailed it down. Everything was reading normally 3 weeks ago, but it never worked last Saturday.

I have WEMA fuel sending units.
The analog display in my dash will nudge (1/4" burp) when I turn the key to on.
Then it goes through its cycle where it goes from 8 o'clock to 11 to 1 to 4 oclock, and then back to 8 oclock (Empty)
Changing the tank selection on my A10 from Left to Right, or Right to Left does nothing to the needle.
I unplugged the connector on the back of the analog fuel gauge, and replugged it in.
I unplugged the connector on the back of the A10 panel, and replugged it in.
I unplugged the connector on the back of the Tach/NexSys Link Command center, and replugged it in.
All other aspects of my A10 (Lights, Aerator, Recirc, Bilge, Acc) are working as expected

I think I have a ground/ short issue, but haven't been able to track it down. I am curious what the wire path order of events might be to help me track it down. If anyone else has faced a similar circumstance or might be able to chime in, I would really appreciate it.

Thanks,
Mark

[catmantwo]

Check the connection from the NEXSYS to the fuel gauge. Does the needle in the fuel cycle (I think twice) when you turn the power on/turn the key to "ON" (not start). (Fuel is pin 7 on the back of the gauge (lower level - far right side).
If it does, it is probably a ground wire issue.

Check all ground wire connections to the sending units as well as the junction box at the motor.
Had a similar issue on a new boat and it took my dealer a couple of times to "fix" it. They eventually replaced all the crimp style ground connectors with the MERC plug type connectors.
It's been fine for the last 4 years.

[WMFisher]

Check the connection from the NEXSYS to the fuel gauge. Does the needle in the fuel cycle (I think twice) when you turn the power on/turn the key to "ON" (not start). (Fuel is pin 7 on the back of the gauge (lower level - far right side).
If it does, it is probably a ground wire issue.

Yes, when I turn the key on, it does a full cycle of the fuel gauge. Instantly when keyed on, it moves a 1/4", and then after 1 second, it goes all the way to full and then back to empty. The wires on the connections from the A10, to the Tach/NexSys to the fuel gauge are all solid (no loose wires). I agree, I believe it is a ground issue

Check all ground wire connections to the sending units as well as the junction box at the motor.
Had a similar issue on a new boat and it took my dealer a couple of times to "fix" it. They eventually replaced all the crimp style ground connectors with the MERC plug type connectors.
It's been fine for the last 4 years.

I re-crimped my port side (Left) sending unit pigtails. The ground wire on the sending units mates into my rear compartment LED lights, those lights work perfectly. I checked the terminal block on the transom, all the wires are tight in the crimps, and all screws are tight.

Last night I woke up and realized, I changed by battery configuration about during this time. I had two big Duracell AGMs in parallel (jumper + to +, and jumper - to -) for my big motor and all pumps, lights, electronics, PP. Previous owner ran 4 12"+ graphs, and had 2 giant cranking batteries, and I left them both in. I was getting low voltage at starts, and found the 1 of them was no longer good. I removed the jumpers and now operate my PP and Outboard on 1 battery, and my A10, Lights, Pumps, electronics on the other battery I have replaced.

QUESTION: Does the ground for the outboard need to be connected to the ground for the A10 to have the NexSys Link gauges work, ?

QUESTION: Any harm in re-installing my negative jumper wire between the two non trolling motor batteries?

[WMFisher]

Update! - Solution Discovered - In the midst of my "low voltage" alarm on my console unit when starting the big motor, I found my 1 of my 2 31 AGM cranking batteries, was shot. (Yes, I know its overkill, but having a "double sized starting battery" from the previous owner's setup, I left them in.) I took out the bad battery and replaced with another AGM battery I had laying around. I removed the jumper wires to make them completely separate.

SOLUTION - The ground from the engine, and the ground from the A10 must be shared. I re-installed my negative to negative jumper wire between the batteries, and "BOOM," fuel gauge acts normally. Typically this is all done off of one battery, so never an issue, but with my dual cranking battery setup, the grounds need to be shared.

Hope this helps someone else who finds themselves in this situation moving forward.

[Bigfishwilb]

Great information. Thanks for,passing it along.