Fuel level gauge...

where is the ground located at anyway. and the connector cause mine is doing the same thing. would it be too much trouble to ask you for a pic?

The red/yellow wire (power supply to gauge & sender) should have 12 volts when the ignition is in the start or Run position.

The next steps require dropping the fuel tank and removal of the fuel level sender. Here are some useful tips...

I have done the tank removal three times, and the main issues are getting the car up on jack stands and getting the gas out of the tank. DO NOT try to do this job without jack stands. Becoming a pancake is not part of the repair process.

Pumping out the old gas:
If the old pump still works, you can use it to pump the tank out.
1.) Separate the pressure line (the one with the Schrader valve on it) using the fuel line tools.
Look in the A/C repair section for the fuel line tools. They look like little plastic top hats. You will need the 1/2" & 5/8" ones. The hat shaped section goes on facing the large part of the coupling. Then you press hard on the brim until it forces the sleeve into the coupling and releases the spring. You may need someone to pull on the line while you press on the coupling.


Use a piece of garden hose to run from the pressure line to your bucket or gas can. Make sure it is as leak proof as you can make it. Fire and explosion are not part of the repair process...

2.) Jumper the fuel pump test point to ground.

Turn the ignition switch to the Run position. the fuel pump will pump the tank almost dry unless the battery runs down first.

Some 5 gallon paint pails lined with garbage bags are good to hold the gas. The garbage bags provide a clean liner for the pails and keep the loose trash out of the gas so you can reuse it. If you decide to use a siphon, a piece of 1/2" garden hose stuck down the filler neck will siphon all but a gallon or so of the gas.

Remove the filler neck bolts and put them in a zip bag. Disconnect the supply & return lines by removing the plastic clips from the metal tubing. If you damage the clips, you can get new ones form the auto part store for just a few dollars. I have used tie-wraps, but that is not the best choice. Then you remove the two 9/16" nuts that hold the T bolts to the straps. Put the nuts in the zip bag with the filler bolts. Pull the plastic shield down and away from the tank. Once the tank drops a little bit you can disconnect the wiring for the pump & fuel quantity sender.

The fuel gauge sender assembly comes out by removing a large metal ring that unscrews from the tank. There is a separate mounting/access plate for the fuel pump and fuel gage. You are supposed to use a brass punch to tap on the ring so that you don't make sparks. Look closely at the rubber O ring gasket when you remove the fuel gauge sender.
When you install the metal ring that holds the sender in place, watch out for the gasket O ring. Some RTV may be helpful if the ring is not in excellent condition.

The tank to filler pipe seal is a large rubber grommet. Inspect it for hardening, tears and damage. At $20 from the Ford dealer, it might be a good idea to replace it.

I used a floor jack to help lift the tank back in place. You may find that it is the only time you really can make good use of a helper.

All resistance measurements should be made with the power off.

Note from bstrd86 - 86 and older fuel tank sender units are 73 ohms empty, 8-12 ohms full.

The yellow/white wire will show a voltage that varies with the movement of the float on the sender unit. To test the sender, set your Ohmmeter or DVM on low Ohms. Then disconnect the sender and connect the Ohmmeter or DVM to the yellow/white and black wires from the sender unit. Move the float arm while watching the Ohmmeter or DVM. You should see the reading change from 22 to 145 ohms +/- 10%.

If the Ohmmeter or DVM resistance readings are way off, replace the tank sender unit.

Use extreme caution if you do the next step. Fumes from the gas tank can easily ignite and cause a fire or explosion.
With the sender unit out of the tank and connected to the body wiring harness, turn the ignition switch to the Run position. Move the float arm and the fuel gauge indicator should move. If you are very careful, you can use a pair of safety pins inserted in the connector for the yellow/white and black wires to measure the voltage as you move the float arm. The voltage will change, but I have no specs for what it should be.
Do not short the safety pins together or to ground. If you do, you may damage the anti-slosh module or crate a spark. A spark with the fuel tank open could cause a fire or an explosion.

If the voltage does not change and the tanks sender passed the resistance tests, the anti-slosh module or gauge is bad.

1991vert said:

i dont think it's the sender... i think it's the gauge. where does it ground? i had the whole interior out of the car, including the dash, so it's possible i forgot it...


my autometer did the same thing. i had the sender wired up and it had power, but no ground and it read the highest it could for oil pressure until i grounded it

Click to expand...

Go back and check out the diagram with my post. The fuel gauge grounds through the sender and anti-slosh module.

1991vert said:

i take it the anti slosh module is in the tank as well

is there anyway to check behind the cluster with a volt meter to see if it's grounded?

i have 2 wires coming out from the sender. i believe one is yellow and the other is black. the black gets soldered with a few other ground wires in the trunk area and then grounds to the panel where the inertia switch for the fuel pump is mounted

Click to expand...

The anti-slosh module is mounted on the back of the instrument panel circuit board. See http://forums.stangnet.com/609704-voltage-regulator-aka-slosh-module.html for more information on the anti-slosh module. Someone posted a picture of what the little bugger looks like, but a quick search on anti-slosh didn't find it. You may have better luck.

All the electrically operated gauges use a common ground. If the ground were bad, I would expect to see problems with all the electrically operated gauges.

Unfortunately you can't edit your posts after 24hrs so dead links can't be fixed and posts can't be updated.

Here's a pic of the two styles of slosh modules. The square style is screwed down onto the back of the instrument cluster. The 'T' style slides into a slot in the back of the cluster like a credit card.

Let us know how it goes. My 89s gauge hasn't worked since I got it in 99 or so. If I remember correctly, it always reads full, but sometimes after a long drive it starting reading somewhere in the middle.

I guess its a good/bad thing, but since I have a H/C/I/14psi setup, I have a fuel pressure gauge. It reads about 40psi, but when I am low of gas, it reads about 37. I know I need to fill up every 200 miles or so, but the fuel pressure gauge helps also. I really want to get that damn gauge fixed someday though.

So if I have the t shaped anti slosh module can I just pull it out? If so I can get another one from my local junk yard. My gauge has been reading full at all times for a few months now.

The 'T' shaped module has a little plastic locking clip that you squeeze to pull out the module. It's the brown piece in between the spring contacts. The end of the clip is broken on the one in the pic. Squeeze the clip and the module should slide right out.

I just ordered a sender also]

Great!!! My fuel gauge always reads empty....I'm gonna have to do some checks. This is a great tech post!

Thanks!

Well I installed a new sender and mine still reads full or 3/4 full.
What's the next step?

antislosh card?