lcd marine meter speedo error fuel

[Piero]

Hello to everyone, sorry for my english but i am italian.
I have a problem with my speedo when the tank is full it's display empty and when the tank is empty i see full.
I connect the white/blu to a wire of the fuel sensor and the other to black of the gauge, I olso tryed with the white wire but i don't see difference.

[ressiv]

perhaps the sensor reads air instead of gas???

[Piero]

???

[Ken]

Piero,
Your English is much better than my Italian [img]smile.gif[/img] !
There are many different senders that go into the fuel tank and different colors for the wires.
Here's what is on my setup for a 2000 C115.
There is a red wire that connects to the center of the sender and there are two wires that connect to the outer ring, black and green.
I assume the red and black go to the LCD tachometer that has a bar graph on the right to show fuel level. The green is a gounding wire for safety from static discharge and I believe it goes to the filler neck, but not sure.
If your fuel gauge bar graph has always read backward, then I would try to switch the two wires at the meter. If your fuel gauge was at one time reading ok, but now is reading backward, then I think the fuel sender is bad, or there is a bad connection at the sender or gauge.
Hope this helps [img]smile.gif[/img] ,
Ken K

[Cruiser]

Piero,

If this problem has always existed you might find there are a couple of dip switches (tiny little switches) in the back of the speedo or tacho that need changing to suit your fuel sender. The switches are hidden behind a rubber bung.

You will need the instruction sheet for the speedo to tell you how to set the switches correctly.

Chris in Australia.

[GWDolphin25]

I have a similar problem. I have 1991 engines and the original digital speedometer that came with them went bad so I got the newer kind that works with 1995 or newer engines. I got most colors matched and got it to come on. Now, I have two tanks and the sender signal (I connected to the white wire) is switched at the rocker panel. When I go to one tank I only get a full signal (when it's not) then when I go to the other I get an empty (when it's not) or no signal (just one bar flashing). I will be tracing the wiring to check for connection problems, but I figured I'd ask here too.

[Hamfisted]

GWDolphin25 it's probably the sending unit in each tank that's crapped out. They're cheap. I recommend the Centroid electronic senders as replacements. They fit the standard SAE 5-hole bolt pattern for the tank, you just order the appropriate depth unit and trim the tube length to fit. You can test the circuit to each tank by shorting the two wires together at each sender unit (one tank at a time...) with the key ON, the fuel gauge should show FULL. If it does then the wiring circuit and the gauge are Ok and the problem is the sender. I have the same boat and replaced my senders, and re-glassed the main deck floor above the main tank. The wood had gotten wet and rotted. Replaced the wood with stainless mesh and glass, now it's bulletproof.


-Mike

[GWDolphin25]

Turns out that checking all the wiring and contacts did the trick. After some troubleshooting, the gauges started giving the correct reading. Thanks! This forum is the best.