Fuel tank to gauge wiring

[WadmalawJoe]

I am struggling to find the info on here for this. I apologize if I overlooked it somewhere. Where the fuse panel is labeled fuel gauge the previous owner has a wire running from there to the fuel tank. This is the only wire going to the tank. Shouldn't there be one to the tank and one coming back and shouldn't the wire be going from the fuse panel to the gauge since it says fuel gauge?? Any help would be greatly appreciated.

[jjzepplin]

One ground off the fuel tank sender And the one brown one from the fuse box is all there is.

[WadmalawJoe]

I think I need to start from scratch...
I have no brown wire.
So, fuel level sender unit gets a ground wire then what?
Looking up at the back of the fuel gauge I see a empty peg sticking out. Shouldn't a wire go from there to the fuse box?

[jjzepplin]

The sender has a peg sticking out and that is the wire that goes to the fuse box. Usually just pushes on like your cig lighter. There should be some sort of ground wire that comes from your sender that can go to your frame or such. As far as I know the gauge should get all it's wiring through the printed circuit on the back of your cluster.

[TobyArnot]

Hello Joe,
The wire from the fuse block goes directly to the post on the tank sending unit. The sending unit is also grounded. As stated, all the other wiring for the gage itself is part of the dash circuit board. Hope that's clear enough.
Good Luck,
Toby

[bonnieclyde100]

yes the gauge gets its power from the printed circuit board on back of cluster.you have a power wire from the fuse box to the gauge and the you have a ground wire from the gauge to the sending unit in the tank and a ground wire from the sending unit to the chassis. there are actually 3 studs from back of the gauge the bottom one goes to ground 1 of the other 2 goes to fuse box the other goes to sending unit.

[WadmalawJoe]

Thanks everyone, especially BonnieClyde.
BonnieClyde, I did noticed there was two other studs sticking out making it three studs.
So,
bottom one to ground
other 2 studs, one goes to fuse box (I imagine where it says fuel ga.) then the other to the sending unit.
Does it matter which one to what?
It would be a bummer to blow myself up

Previous person did a partial re-wire and screwed it all up. Half the gauges don't work. I made sure to knock a few dollars off the price when I saw that. Wiring in my opinion is not the place to just wing it. Next thing you know, half your electronics are fried or worse case a fire.

[bonnieclyde100]

yes i think it does matter . follow the circuit board to the conector and the one that goes to the pink wire will be the power wire from the fuse.the other i think is tan that goes to sending unit.

[bonnieclyde100]

check the ground wire from the dash connector it would keep
most of the gauges from working

[WadmalawJoe]

Awesome thanks, I will check on the ground. As far as wires and various colors, they are not there, I think he pulled them all out except for ones with the pin type connection, like the 12? pin connection is plugged in and thats about it. Speedometer works, oil pressure works and..........turn signal arrows..lol
OOO the high beam warning light works.
I think that's it.
He added a engine temperature and anmeter? gauge after market stuff. I want to see if I can get original gauges working and get rid of aftermarket add ons.
Engine temperature gauge goes to like 1,000, what's up with that? Needle barely even moves, starts at 100 degrees.

[WadmalawJoe]

I just re-read your advice bonnieclyde, I missed the part about tracing the circuit board lines to the pink or tan wire at the connector. Thanks again
I will repost when I get it fixed or if I have more questions.

[bonnieclyde100]

if you look at gauges from back ithink top left stud goes to sending unit the other top one goes to fuse

[WadmalawJoe]

I finally had a chance to look into this today.
The tank unit only has one stud.
I'm thinking this is supposed to connect to gauge.
He had that plugged into fuse box. I wonder if sending unit is now fried???
Posted via Mobile Device

[GMCJOE]

This thread should help you out. If you know how to work the site the wiring diagrams are on, you can down load them to your computer. Very nice job the guy did that put them on here. Colored and all, it will help you get it fix very quickly.

http://67-72chevytrucks.com/vboard/s...d.php?t=185856

[VetteVet]

Originally Posted by WadmalawJoe

I finally had a chance to look into this today.
The tank unit only has one stud.
I'm thinking this is supposed to connect to gauge.
He had that plugged into fuse box. I wonder if sending unit is now fried???
Posted via Mobile Device

the tank sending unit goes to the fuel terminal on the fuse panel. It should be a tan wire. The sending unit must be grounded to the tank and the tank must be grounded to the cab which should be grounded to the engine and the negative terminal of the battery.

The tan wire for the fuel gauge goes from the back side of the fuse panel through the harness to the gauge panel to no. 4 on the pin connector. From there it goes to the fuel gauge sender terminal via the circuit board.

The power side of the fuel gauge goes from the back side of the fuse panel to pin 3 of the dash plug. The circuit board then sends it to the fuel gauge. If you had an idiot light dash the pink wire would go to pin 7 but You have the gauge dash if I read you right. This has been covered already but I thought I would summarize it for you.

What does the gauge read if you pull the sending unit wire off? It should read at the 3:00 position. If you ground the sending unit wire to a good ground the gauge should read empty.

BTW my wife grew up on Johns Island about a mile and a half east of the John's Island High School just off Maybank highway.

[WadmalawJoe]

Holy smokes your right. I unplugged wire from tank and gauge went to the 3 o'clock position. So what now? Y'all lost me.

My mother inlaw is from Parma? Michigan.
Posted via Mobile Device

[WadmalawJoe]

Here are a couple pictures of my fuel tank connection.

[WadmalawJoe]

When the wire is connected it reads empty,
when unconnected it goes to the 3 o'clock position.
(tank is full)
So the sending unit needs to be grounded better?
If I unscrew the unit and clean the locking ring and such so I get a better metal to metal connection and maybe a tank securing bolt as well?

[VetteVet]

Taking the sending unit wire off and getting 3:00 on the gauge proves that all is well back to the sender. Take the sender wire and touch it to the tank or the sender mount and see if the gauge goes to empty. If it don't then the sender or tank ground is bad. Since you are reading empty then my money is on a bad sending unit. If it reads empty with a full tank then either the float is stuck down or the float is full of gas which is very common with these old trucks.

[WadmalawJoe]

Got it.
I will give it a shot and see.
Thanks a lot!
Posted via Mobile Device

[HEADTURNINGC10]

I have my gauge stuck at 3:00 position how do you make a better ground for the tank/sender? What does the purple wire go or do?