Fuel gauge issues

[johnbeck]

My fuel gauge isn't working. I put a new gauge in, checked and found continuity across terminals. The tank plug is well grounded, I ran a loop of wire into the two connections to make a circuit. Turned on the key - no gauge movement. That said, behind the dash is likely my problem. I removed my reserve tank and disconnected wires on the fuel tank switch that I thought were for that reserve tank, not intending to reinstall it. That was two plus years ago. Behind the dash, on the back side of the fuel tank switch, there are three male wire attachments. The one farthest driver's side has a yellow wire, the middle an orange wire with a long blue connector, and an orange wire with a long red connector far passenger side, and a single male wire connector directly beneath it with no wire connected. My goal was to bypass the no longer needed fuel switch. The fuel gauge its self has a black with white wire attached, and the orange wire with blue connector that is coming from the center connector of the fuel switch. The orange with red connector that is attached to the f switch is six inches long with a round connector, but isn't attached. A single orange wire paralleling the yellow wire emerging from the main loom is not connected. Shoot Me! Any thoughts? (No wire going to the amp meter -Color?) Thanks!

 

[Oleguy 74]

orange wire is main tank.connect orange wire from switch to orange wire to the gauge.also are temp and oil gauges working?

 

[johnbeck]

After changing the oil pres. and water temp. sending units they both are working. Bypassing the switch, is the orange wire that emerges with the yellow wire from the harness the wire from the main tank, and can it be attached directly to the fuel gauge? Where does the yellow wire go that I have attached to the fuel switch? Is it the reserve tank wire or does it attach somewhere else? Thanks

 

[Oleguy 74]

yellow wire is the aux tank.orange wire from sw to gauge will go to orange wire from harness.orange wire is the main tank

 

[johnbeck]

Thanks Oleguy. I'll cap off the yellow and run the orange wire from the harness directly to the gauge and bypass the switch. Any idea what color wire I should be looking for to connect up to the amp gauge?

 

[DirtDonk]

Is it a replacement voltage gauge, or the original ammeter? If original, is there still a rubber-coated metal loop on the back?
If so, then there should be a larger gauge Black w/yellow stripe wire and a large push-together ("bullet") connector nearby.

Regarding the fuel gauge wiring, Ford made it so the same wires were used whether you had the standard single tank, or the optional dual tanks. So you don't have to re-wire anything to bypass the switch. Simply connect the two Orange wires together and you have a circuit!
There is an oddly sized 90° on the wire coming from the gauge, and a matching connector from the tank sender. Find them, separate them from their existing mates if needed, then connect them together. Voila! Switch bypassed.

Paul

 

[DirtDonk]

Back to the Black w/yellow wire... This is the main power source for the entire truck. If you disconnect the bullet connector then literally nothing in the truck works. So whether it's running through the loop on the back of the gauge, or simply laying around somewhere, you know that it's still connected because it sounds like your other accessories are still functioning.

Since it's connected directly to the back of the alternator at one end and the battery via the starter relay on the fender at the other, to work on the ammeter wire you should disconnect the battery so you don't see sparks fly while you're stuck under the dash.

Paul

 

[johnbeck]

I connected the orange wire from the tank to an orange wire going to the fuel switch and the gauge now works. I'd eventually like to remove the fuel tank switch but don't want to leave the hole in the dash. The black with yellow wire and bullet connection is right next to the gauges and the rubber lined loop is located on the back of the amp gauge - What's missing to connect to make the gauge read amps? Thanks, John B

 

[DirtDonk]

Nothing. That loop is the inductive-pickup for the amp signal, so all you need to do is separate the two halves of the wire at the bullet connector, run the wire through the loop, then re-connect them together.
It basically just sits there inside the loop and the instrument picks up the small waves passing through the wire and reads it on the needle.

Not sure why someone would disconnect the gauge, but maybe they were afraid of ammeters in general and did not note that this type of ammeter is perfectly safe.
Or they just made a mistake when working on the system.
Either way, you can put it back through the loop and see if the gauge still works.

You familiar with how these ammeters read? If so no problem, but I wanted to ask because most owners are not familiar with this older type of instrument.
Easy to test to see if it works and if you have the wires passing through in the correct direction. Just turn on the headlights and you should see the needle move slightly to the negative side. Turn on the heater and high beams and it'll go a bit more. Hazards and you should see it go more negative and then back a bit as the lights flash.
Easy test.

Paul