Yamaha LCD multi function gauges

I bought a used Aluminum lifetimer boat recently and it came with both the Yamaha multi function gauges, Speedo/fuel/time and Tach/trim. Unfortunately someone opted to put in aftermarket gauges. The Tach is working minus the trim and there is power to the speedo but that's about it. Unfortunately it appears as though the original plugs have long been severed. I would like to get these gauges up and running. I sucked some water out of the speedo and it may be working now. At least when I blow in it there is and indication its working. Haven't tried it in the water yet. I believe both gauges are the same age as the boat and engine, 1991. The most important issue is the fuel gauge. It shows empty and the warning light is flashing. The white with blue wire is connected to the sender wire but there is a second solid white wire which goes no where? When I apply power to the solid white wire the fuel gauge doesn't work but the digital display goes to 16?<br />I believe the sender has been replaced. Does the sender have to match the gauge? The sender wire has a voltage reading of around 5 volts. The sender wire is also connected to the after market gauge. Would this make a difference? Thanks. PS the aftermaket fuel guage isn't accurate either. A full tank indicates about 3/4?

Re: Yamaha LCD multi function gauges

The sender unit does not have to match the guage, but the sending wire should not be hooked to more than one guage since it measures resitance. I have had to hook a ground wire to the guage and tank direct from the battery due to the increased resistance in some boat wiring harnesses because of length of wire and connections to get the fuel guage to work properly. The trim signal wires are a seperate harness that runs from the motor to the guage. You may have to add this if not already in the boat to get trim guage to work.

Re: Yamaha LCD multi function gauges

Thanks Ray, any idea what that solid white wire is for? Jeff

Re: Yamaha LCD multi function gauges

No I don't.

Re: Yamaha LCD multi function gauges

Thanks Ray part way there. I disconnected the second gauge and now I have a reading on the Yamy gauge. Now I just have to make it accurate. I'll try grounding the gauge and see where that gets me. J

Re: Yamaha LCD multi function gauges

OK, a few hours later.........Full tank two fuel gauges each read half full. Resistance from sender is 103 ohms. Now I am thinking that the sender itself must be installed incorrectly. I believe 103 ohms is correct so that would suggest to me that the sender is only half way engaged. Sound right? J

Re: Yamaha LCD multi function gauges

I have seen senders installed where they hit the side of the tank before getting to the top. You can remove sender and test with wires hooked up if you are carful.