Ok so i installed a 36 gal bronco II tank in my HB during my build. I used the bronco sending unit but kept the HB gauge. My problem is i dont know if my gauge is calibrated to the stock sending unit or not. I dont know if my gauge is reading the correct amount of fuel. How the heck do i find out or do i need to change the gauge
Any help would be nice.

Tim

 

Someone correct me if I am wrong, but I think the sending unit is basically a resistor. When the tank is full, the float has the lowest resistance allowing full voltage to the gauge giving the "F" indication on the gauge. When the tank is empty, the float is at its highest resistance giving the "E" indication. You check sending units by doing a resistance check with a volt meter. So as long as that sending unit is the right one for the tank and the unit is in good working condition, there should be no problems. Pretty sure the gauge can't be calibrated. But I could be wrong. It's been 15 years since Vo-Tech in high school and being a sailor, A LOT of adult beverages have been consumed since then.

 

I am thinking the same thing you are. The sending unit is new and been checked and its good but when i put 16 gals in the gauge reads full. Thats what is throwing me off

 

If the sending unit is reading good on a volt meter, then I would think there is a short in the gauge itself. Probably at the half mark. Not sure how you would check that.

 

If i ground out the sending unit and the gauge pegs full. The gauge is good. I have another gauge but its a pain to swap out

 

Might have to take out the sending unit and bend the rod some... That will change what the gauge reads at what level inside the tank. You need to bend it up

 

find out the factory ohm readings for both vehicles and compare. the gauge doesnt care what vehicle its from, it only registers what its told

 

The correct ohm readins is 73-10 ohm (full-empty) for your dent. Ford went to 16 full -158 empty after 1987... so what year did your tank/sending unit come from?

If it doesn't match the gauge it will be much easier to rewind the sending unit that it will be to re-calibrate the guage.

 

Elkarcher - Did you ever resolve the issue?


I am getting ready to install a 85-86 Bronco sending unit into my truck and the site lists the ohm's at 70 ohm Full - 10 ohm Empty. From the post above, it should work out ok.


I have found contradictory information on this site.
https://www.ford-trucks.com/forums/1...uage-woes.html


and https://www.ford-trucks.com/forums/1...ge-issues.html


If one were to reverse the connections on the back of the fuel gauge, would it cause the needle to swing in the opposite direction?


*EDIT* - Better yet, maybe getting a 85-86 fuel gauge to fit the 73-79 gauge cluster. More to come on this I'm sure....

 

I'm pretty sure the 10-70 or 9-73 Ohm is a standard Ford spec... sending units do vary in terms of length and sweep of the float arm and resistance windings to accommodate different tanks. The stock fuel gauge in my cluster stopped working so I added an Autometer Ford spec gauge. Later, I put a 38 gallon tank in my '78 F250 and re-pop sending unit for a standard 19 gallon tank. The fuel pickup was lengthened to get to the bottom of the tank.

As far as the gauge... well its a 19 gallon gauge in a 38 gallon tank. I checked it at installation with a bunch of 5 gallon cans full of gas. Check the gauge reading, add 5 gallons, check again. After 18-20 gallons it showed full and I drove a couple of miles to the gas station and added about 18 more.

Mine stays on full while driving for quite a while. Then starts dropping. With a full tank the float is submerged and the gauge just reads full until ~15 gallons are burned.

Sounds to me like you have the same situation. Maybe the gauge does not have enough length or sweep for the bigger tank. To be sure, drain it completely, add gas in increments until it won't take any more and check gauge readings as you go.

My gauge is still useful... just needs some interpretation. Still, it would be really nice if somebody made a gauge set up for these deeper tanks.

 

I actually have no problem with my current sending unit. I am swapping to the 85-86 sending unit for other reasons and I wanted to know if the 85-86 sending unit will cause any issues with the 73-79 fuel gauge.


I might just modify my current sending unit to do what I want. It's still up in the air what I am going to do.