Fuel gauge not working

[1970blazin]

My fuel gauge stopped working about the same time I pulled out my dash cluster to add a tach kit in. My dash lights don't work, and neither does my amp gauge. My blinkers light up and work, and my speedo works... What are the possible problems:
1.Need new gauges
2. Sending unit in gas tank
3. Short in cluster
4.????
What should I look for if I remove the dash cluster again.
Thanks-
Diane

[JimKshortstep4x4]

I would suggest making sure the dash cluster is grounded before going any further. Lack of ground could cause most if not all of your problems.

Jim

[1970blazin]

Jim- where is the ground wire located or ran to? Thanks
Di

[vtblazer]

Mine just quite also out of the blue...nothing.
Sorry to hear about your problem Diane but kinda glad to hear I'm not alone on this...
Everything seems to be connected, still no reading on my fuel level.
I was on empty when I filled my tank...it's never registered since

[nitor]

I didn't have all of the problems you all have, but my fuel gauge did quit working. I filled the tank on evening, the gauge read full, came out the next morning, the gauge read empty. I even went as far as to put a stick in the tank to make sure I had gas. The gauge would move when I was driving, but would never go to full. Well come to find out, the float filled with gas. I took the sending unit out, replaced the float, it worked fine.

[vtblazer]

Yeah, I'm thinking my float sunk...out comes the tank

[Robert1970C20rstbukt]

I had the exact same problem with the float in mine. Turns out it had a crack in it about 5/16" long. I took the sending unit out, removed the float, and soldered the crack up and it's been working great. Easy fix, except for having to take the seat out.

[buckola]

Mine sticks. It will stay in one place for a while then suddenly drop. Sender must be rusty, stick, or hung up on something

[JimKshortstep4x4]

Diane,

We just make up a ground wire and attach one end to the cluster using one of the small screws. The other end is attached to the dash. We make the wire out of a piece of #16 black wire 12-14" long with eyes on each end for easy attachment. With a separate ground wire you can be sure the cluster is grounded.

Next steps after grounding cluster if no improvement is noted.

Make sure that plug for cluster is seated.

Ammeter, check small fuses on either side of radiator.

Dash lights, check fuses and light switch.

Fuel gauge, pull brown wire from gas tank plugged into fuse panel and check ohm readings. Reading should be between 0 and 90 ohms. Ohm readings are linear, 0 = empty, 90 = full, any where in between for example 45 ohms would be 1/2 on the dash gauge. If no ohm reading from tank, than the problem is in the sender, the wire, or no ground on the sender unit. If the reading is 0 and you know there is fuel in the tank, than there is good chance the wire is grounded.

Most of the time the dash gauge is good and the problems are in the wiring or the sender.

Good luck!


Jim

[vtblazer]

Good info JimK, getting out the tester!

[Duallie]

If the gauge always indicates below Empty, its shorted to ground somewhere.
If the gauge always indicates above Full, theres an open circuit somewhere.

[1970blazin]

Duallie- my gauge always reads Empty and it never moves or bounces. So a wire may be shorting somewhere?

[Duallie]

Probably. Or the sender is shorted. The fuel sender wire is likely bad someplace under the door sill cover. I pinched the sender wire between the steering column and it's bracket once.

[Stryker67]

Hey all. I have been struggling with my gauge as well. I connected my multimeter to the wire from the sending unit, and the other probe to ground. I should have registered an "open" circuit, but I actually read resistance. I can only assume there is a short. The gauge reads 1/8 no matter what. I just did a restoration to the truck, and I don't know if the float or gauge even worked before.

[Duallie]

If the gauge is stuck someplace other than past Full or Empty, then most likely the gaugehead itself is bad. If it moves but is way inaccurate, then most likely the sender is bad, sunk, or wrong.

[SnS C10]

hi i just got a 72 3/4 ton gmc pickup and the fuel gauge doesnt work either. i decided to just try and use a vdo gauge i had in the garage which is brand new. i hooked up a ground wire and put the sending unit wire into the gauge also. i also hooked up a power wire from the fuse block, and i know it has power because its the same terminal my radio is hooked into. With all 3 wires attached, the gauge reads over full, all the time, and i know my tank is not close to being full. if i unhook the ground, it still reads over full. what do i need to do to get it right? is there supposed to be a ground wire on the tank somewhere, or the only wire on the tank is for the sending unit? thanks for the help

[Duallie]

You probably have a VDO gauge designed for a non 0-90 ohm sender.
Ford uses a completely different resistance range, for example. Something like 270 to 100 ohms, which may explain your gauge reading high constantly. There may be some code on the back of your VDO that may indicate its expected range.