needing dentside wire diagram for gas gauge and sending unit

[Evan's f250]

I have a 1978 F250 4x4 dentside with dual tanks that I am needing to get the fuel gauge working.

I'd like to have a diagram of the fuel gauge wires and of the wires that go to sending units. (dual tanks)

I got under there and couldnt find where the wires went to.


Your help is greatly apprecitated,

thanks,
Evan

 

[Mil1ion]

click 4 times for large view

 

[Evan's f250]

Thank you, Also I remember that when I drove my truck home from when I bought it that half home, the gas gauge and turn signal indicators on the cluster both stopped wrking at the same time.

After I had got it home the fuel gauge had worked some in the yard while I was moving it around and fixing it up, idk if the turn signal indicator was working, as it wasnt on the road.

Now, since I've got the truck all together and going, the gauge nor the turn signal indicator on the cluster have been wrking.

I'm thinking these two problems are tied together?

Any help is appreciated

thanks

 

[Mil1ion]

I would suggest removing the cluster and cleaning all the connections by removing the gauges and bulb holders.
What happens is corrosion finds its way to the elctrical connectors then all sorts of strange things happen with current trying to find a ground.

CLusters are prone for corrosion.

 

[Evan's f250]

I would suggest removing the cluster and cleaning all the connections by removing the gauges and bulb holders.
What happens is corrosion finds its way to the elctrical connectors then all sorts of strange things happen with current trying to find a ground.

CLusters are prone for corrosion.

Ok, will do. wht would you suggest to use to clean them up?

Thanks

 

[Mil1ion]

an eraser for the copper contacts and then electrical contact cleaner
Make sure your ground wire is securely grounded as well

BTW, You didn't need to use the Quote feature since I am the only one replying

 

[Evan's f250]

Ok, thanks. I'll do that. Where exactly is the ground wire that I'm needing to check? I have a cluster in the garage that still has the plug in the back. Are you refering to the 3 black wires that are in this wire plug that fits into the cluster? It has 3 black wires. I'd think that would be the ground?.

sorry for so many questions, just annoiying not having a gas gauge

 

[Mil1ion]

Yes that's them, make sure they are securely grounded to the Dash Brace.
People seem to forget that they are not only painted,they also corrode when the metal meets.

 

[Evan's f250]

Thanks for all the help Dennis. Got the turn signal blinkers and the other illuminations that weren't working on the cluster by cleaning it up like you suggusted. Also got the aux tank registering on the gauge. I believe the main tank has been changed out for a plastic reproduction tank, I'm pretty sure the original was metal, atleast thats what most sale in the catalogs as oem replacements. I'd say that the sending unit in this tank is not the right ohms for the gauge, so I need the original type sending unit that would be in these.

I'm going to try to find a good working used sending unit for this main tank. If anybody has one laying around, let me know. I just dnt feel like sending $65 on a new chinese one.

 

[Mil1ion]

You can still buy OEM NOS fuel sending units and yes the one for the plastic tank is different than the metal tank but I've never seen a metal tank in a 78.

Part # D9TZ-9275-A

description/engineering # stamping on part

D9TF-9275-AA

 

[fatherdoug]

When you say, "plastic" tank, is that the tank that is closest to the cab? I'm not going to say "main" or "aux". Some of the '78's came from the factory with a 26 gal plastic tank that ran along the framerail. (I have a picture in my gallery.) Finding a replacement for it is next to impossible, but, as Dennis listed, you can still get the sending unit for it.

 

[Mil1ion]

The Auxillary tank is always known as the MID-SHIP tank

The main tank is between the frame rails at the rear of the truck

 

[fatherdoug]

The Auxillary tank is always known as the MID-SHIP tank

The main tank is between the frame rails at the rear of the truck

Quoted from the 1978 F-150 owner's manual(page 9): " On vehicles equipped with dual fuel tanks, the "MAIN" position supplies fuel to the engine from the midship fuel tank.??????????

 

[Mil1ion]

 

[Mil1ion]

Quoted from the 1978 F-150 owner's manual(page 9): " On vehicles equipped with dual fuel tanks, the "MAIN" position supplies fuel to the engine from the midship fuel tank.??????????

That's correct. The problem is the interpretation of those words.

From the 1979 owners manual Page 9 it says: On vehicles equipped with dual fuel tanks the FRONT (UP) position supplies fuel to the engine from the Mid-ship tank.

Front position is switch UP
Rear position is switch DOWN

 

[Evan's f250]

When you say, "plastic" tank, is that the tank that is closest to the cab? I'm not going to say "main" or "aux". Some of the '78's came from the factory with a 26 gal plastic tank that ran along the framerail. (I have a picture in my gallery.) Finding a replacement for it is next to impossible, but, as Dennis listed, you can still get the sending unit for it.

Yes, thats the one. Do u happen to have the sending unit out of the tank in your gallery? just wondering. I have now found out that my rear tank needs repair, leaks

 

[Evan's f250]

That's correct. The problem is the interpretation of those words.

From the 1979 owners manual Page 9 it says: On vehicles equipped with dual fuel tanks the FRONT (UP) position supplies fuel to the engine from the Mid-ship tank.

Front position is switch UP
Rear position is switch DOWN

Yep, on mine it says main and aux. main being in the down position and aux being up.

 

[Mil1ion]

I think it was a fuel tank selector wiring mistake.

 

[Evan's f250]

This is the part # for the 26 gall plastic tank? I'm having a bit of trouble locating this sending unit for some reason, even with the part #.

 

[Evan's f250]

I think it was a fuel tank selector wiring mistake.

Nevermind, your pic is the same as how mine is labeled, the pic wasnt showing up completly earlier, thanks

but yes, when I have it on main, it runs off the 26 gall plastic tank like stated above.