Trouble with gauges wiring

[zach103]

Last year i was having trouble with the gas tank readings and the fuel gauge turning on and off. So this year i replaced the sender unit and realized that the old one was not installed right so when i had a half a tank of fuel it read 3/4 tank. Well i went and hooked that sender up to the fuel gauge and had some problems with it not reading.. after some trial and error i realized that when the light was hooked up the gauge next to it it caused the fuel gauge to read empty. so im assuming that i have the wrong wire somewhere and its grounding the gauge or something of that nature.. heres some pics of the gauges.

The blue is coming from the control panel for the lights

 

[Silvertip]

Re: Trouble with gauges wiring

Here is how gauges need to be wired. I assume the gauge on the left in the first picture is the fuel gauge. Correct
If so, then the blue wire is feeding +12 volts to the "L" (light) terminal on the gauge. That terminal is jumpered to the next gauge and the next etc. That is correct wiring.
A red wire normally indicates it is carrying +1 volts. If that's the case it is on the wrong terminal. You have it on the "S" (send) terminal which comes from the threaded terminal on the fuel tank sender. That wire is normally pink.
The best way to sort this out is to look at the back of the tach. There should be a wire running from the IGNITION terminal to the "I" (ignition) terminal on the fuel gauge. Look at the GROUND connection on the tach. There should be a wire running from it to the GROUND connection on the fuel gauge. As you have it, I think you have everything wrong on the fuel gauge except the light.

 

[zach103]

Re: Trouble with gauges wiring

The red wire on the sender is actually pink and going to the sender.. than the green wire is from the sender to the ground along with the main ground. the wire with the red tape is the power from the ignition.. i think my problem is part of the ground or light going to and the speedo

 

[Silvertip]

Re: Trouble with gauges wiring

If you think its a ground problem, disconnect the light wire on the gauge. See what happens. The ground for the sender should not be on the gauge ground but rather the negative terminal of the battery. It should still work as you have it but why run wire all the way to the gauge when the battery is about two feet away. Just follow the diagram I posted and it will work. Note how the light, ignition, and ground wires jump from one gauge to the next. If you simply pick one function at a time (Ignition for example) and follow it from the source to the last gauge in the string. Then do the same for ground. Then do the same for light. If the light has a separate ground, connect it to ground.

 

[zach103]

Re: Trouble with gauges wiring

The blue wire is not hooked up to the fuel gauge that's the only way the fuel gauge is working. As soon as I hook it up the gauge turns off. The gas tank sender is 3 ft from the gauges where as the battery is in the rear of the boat. That's why the ground is on the gauge

 

[SteveMcD]

Re: Trouble with gauges wiring

The vast majority of fuel gauges run from positive, through the gauge, to the sender potentiometer and to negative, completing the circuit. If the sender isn't grounded, it won't work. The gauge just needs a negative to make the light work. Blue is the color code for lighting. Gauges can't tell the difference between a sender, a light bulb, or whatever else the PO has in store for you. Grounding the sender connection will cause it to deflect.

 

[zach103]

Re: Trouble with gauges wiring

So what your saying is that if I remove the ground from the sender and ground it somewhere else that should solve the problem? And ican just ground the sender to the tank?

 

[skyviper]

Re: Trouble with gauges wiring

So what your saying is that if I remove the ground from the sender and ground it somewhere else that should solve the problem? And ican just ground the sender to the tank?

You can ground the sender to any ground point that has a connection to the negative terminal of your battery. If your tank is grounded to your battery then you can ground to your tank. I can't say it will fix your problem but it will remove that ground connection from your gauge.

 

[Silvertip]

Re: Trouble with gauges wiring

You can ground the sender to the tank but you then need to make sure the tank is grounded.

 

[RandyJ]

Re: Trouble with gauges wiring

I just wanted to say THANKS so much for the picture/diagram. It helps simplify lots of things. It also shows that every gauge pretty much has 3 wires... ground, positive, and a wire for a light bulb... plus it will have one wire coming from the source or some kind of sender. Now, if I can just figure out which terminal is which on my tilt/trim gauge I'll be fine.

 

[zach103]

Re: Trouble with gauges wiring

I switched my fuel tank ground to the bus bar in the back and I turned on the ignition and still nothing on the gauge. I have it hooked up the same way as the diagram above and still can't figure this out

 

[RandyJ]

Re: Trouble with gauges wiring

Sure you have a good ground on the sending unit and the gauge all the way back to the battery? You have to have a complete continuous circuit for it to work.

 

[zach103]

Re: Trouble with gauges wiring

Ya I did all new connections and wiring

 

[Silvertip]

Re: Trouble with gauges wiring

I don't see any resistance checks of the fuel sender. 33 ohms full tank, 109 ohms, 1/2 full and 240 ohms empty. You need to disconnect the pink wire at the sender and measure from the threaded terminal to ground. The numbers are approximate so a little difference is ok. Drastically different of open circuit says bad sender.

 

[zach103]

Re: Trouble with gauges wiring

The threaded terminal to ground. Are you talking about on the sender or gauge

 

[Silvertip]

Re: Trouble with gauges wiring

The threaded terminal to ground. Are you talking about on the sender or gauge

Did I not say disconnect the pink wire at the "Sender"?? You are testing the sender at this point -- not the gauge.

 

[skyviper]

Re: Trouble with gauges wiring

The threaded terminal to ground. Are you talking about on the sender or gauge

Disconnect from the gauge and measure the sender side of the circuit.