I bought a brand new Bass Tracker Pro Crappie and, with my luck, have one problem with it. Could be worse I suppose.
The fuel gauge is not showing the correct amount of fuel. Empty or full, it reads empty. When switched on the needle actually drops below E a little, very little, slow movement.
I checked the gauge by grounding it, it seems to be fine. I checked the sender, it seems to be fine. Also, as far as I can tell, the wires seem to be fine.
Here’s the part I don’t understand. All the gauges ground to the trolling motor battery, so I used a jumper wire from the ground on the sender to the trolling motor battery. Still reads empty. So, I used the jumper to the cranking battery, the gauge worked fine. Showed correct fuel quantity.
I suppose my question is, why would everything work, while being grounded to the trolling motor battery, but the fuel gauge will not? And, should the gauges be grounded to the trolling batt or the cranking battery? Does it matter?
Your boat wiring problem can easily be cured.
The fuel gauge is basically an OHM meter. 247 ohms for empty and 33 for full. The gauge measures this reading by comparing its ground to the sender’s ground. If the sender is connected to a different ground (your trolling motor battery ground), the gauge will see a resistance much higher than 247 ohms which would make the gauge drop below E. When you add a ground wire from the sender to the same ground that the fuel gauge is connected to (your starting battery), the gauge works correctly.
The rest of you gauges work properly because their senders are mounted to the engine. Your gauges are connected to the engine harness that is grounded at the engine.
Carefully connect all of the grounds together on your boat. I would recommend using a good quality ground block. Connect only a single wire to each battery ground from this ground block.
Hope this helps,