I will post current photos of the winch, gantry, and fiberglass cover when I get home to Baja in early June. Meanwhile, I am way open to suggestions for mounting a spare.


Baja

 

Gavin, just stumbled on to this. Man, this is amazing work! So, I just figured out how to do the rear tank I've been wanting to do. I hope you don't mind if I shamelessly copy your design!

 

Hey Pat, I just finished at Susquehanna, or will in a few hours. Mode 4 coming up, and I am off to manage my fatigue in Baja soon. I agree, Gavin does Nuke grade work, or better. I too am copying his fill pipe design & location. My truck does not have a lift kit, so I can prolly still fill w/o a step ladder.


Baja on the loose

 

How about a bed mount in front of the drivers or passenger wheel well.

Thanks for the complements Pat. I can't remember, is your truck a long bed?

Thanks for the kind words Baja, have a safe trip down south.

Thanks for the PM Pat, I was missing a few details about the sending unit graft.

The GM 82-91 sending unit is stainless, the Ford 73-84 sending unit is zinc plated steel. So I had to make the Ford rheostat mounting plate out of 304 stainless sheet.

Here's the dimensions for the plate.



I got both sending units from RockAuto.

PLATINUM PRO Part # FSU010068 Fuel Sender. Sorry, sometimes RockAuto will not give you a link to a part.

SPECTRA PREMIUM Part # FG73A

 

Yep, mine is a long bed. Added those part #'s to the list, should be able to order all of this next payday.

 

I know this is a little late, however the GM->Ford sending unit electrical conversion can be done easily with 2 resistors.
The opposite direction is still an issue, and would have to be solved.
To convert 0-90 ohms to 8-70 ohms, add a 8 ohm resistor in series with the sending unit. This effectively changes the range to 8-98 ohms. Then add a 2nd 300 ohm resistor across the sending unit and the other 8 ohm resistor (in parallel). This gives a new range or 8-73 ohms.

Full = 73 ohms (ford is 70)
3/4 = 55 ohms (ford is 54)
1/2 = 40 ohms (ford is 39)
1/4 = 21 ohms (ford is 23)
_E_ = 7.8 ohms (ford is 8)

Not sure what the current though the circuit is, the resistors may need to be more than the standard 1/8Watt.

If anyone has questions send me PM

 

I'm confused Smoky. You mean 1-8 ohm in series plus 1-8 ohm and 1-300 ohm resistor in parallel? For a total of 3?

 

I was able to get the GM sending unit to show full and empty correctly, but 2/3rds on the GM sending unit float shows 1/3rd on the Ford gauge. Check out the last 3 pics on post #1. You can see the pot in series just to the left of the gauge. I was really hoping I could just invert the GM sending unit.

 

Sorry to confuse, just 2 R's....

The 300 ohm resistor in parallel *should* solve the 2/3-1/3 issue as long as the sending unit resitance to angle is linear (and ford gauge too). In your setup you have just one pot, in series. You need another resistor (or pot set to 300 ohm) in parallel. These resistors can be installed under dash, or back at the tank, doesn't matter.

Also, I am fairly confident that the fuel gauge circuit runs on regulated 5V (aka 'constant voltage unit'), not battery voltage (12V). Otherwise gauge reading will change with reving the engine, turning on lights, ect. 12V may burn out sending unit. 200mA is a lot of current.

So if you can, please try it out so the rest of us can steal your tank swap ideas and spend time cursing at something else.

 

OK Justin, I did it and it worked.

That's as close as I could get to 300.


Close to 8


Full


Sorry about the pic quality, half a tank shows empty on the gauge. My gauge must be faulty so I went back and just read the resistance.

I measured the resistance across the resistors and the sending unit and I got a range of 8Ω to 76Ω that worked great, but the middle 1/2 a tank read 47Ω.....rats!







While I was doing this it reminded me of something, the GM sending unit only gives you 6" of vertical measurement, the tank is 12 inches tall.


I was able to get over 9" of vertical measurement with the extended float arm that should give you much better accuracy as to how much fuel is in the tank.


I gotta get back work on the truck.

 

Here is a little more info about Ford sending units in our trucks.
Fuel Tank Sending Unit Tech - FORDification.com
It makes sense now why my gauge read almost empty at the 1/2 position (47Ω) on the GM sending unit with the 8Ω and 300Ω resistors.
From the fordification page:
Full = 10Ω
1/2 = 25Ω
Empty = 50Ω
Pointer Width Below E = 73Ω

For anyone who needs them I can send you a float arm bent for 9" of vertical travel or just straight wire so you can bend your own float arm. I also have the stainless steel adapter plate for the Ford sending unit.
Just PM me if you want them.



The plates didn't cost me a dime, I had the material and a local shop chopped them up for me then I gang drilled the holes.

 

Good Job Gavin. Will help many in the future. Tried to REP ya for it but the system said I have to spread the Love more 1st.

 

Adding anything Chevy to a Ford is an upgrade.

 

Thanks Jeff! I appreciate the complements.
What if you add Dodge parts to a Ford.

 

Tough one. I'd probably have to go with "bad move."