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This thread is also in the '73-'79 forum.
I have a 1976 F250 4x4 with the fuel tank inside the cab. Over the winter months I replaced the body. The donor truck was a 1979 F150 4x2 from Texas. Since the 1/2 ton didn't have a fuel tank in the cab, I decided to mount a tank in the rear. I purchased a new 1984 Bronco II 23 gal. fuel tank and sending unit from Jeff's Bronco Graveyard. After everything was fabbed and wired the tank was filled. The gauge reads half tank. I drove about 100 miles and the gauge reads empty. I refilled the tank and it took 13 gals. to top it off. I know that this conversion has been done. Does anyone know of an aftermarket gauge that will work with this sender? Any help would be greatly appreciated as I need a working fuel gauge.
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70's fuel sender works from 10ohms full to 73ohms empty. Don't know about the BroncoII. I put a new stock fuel tank in mine with sender already installed and have just about the same results. It may mean pulling the sender and bending the float arm. Not the most scientific approach, but probably the only option. Even a proper ohm'd gauge won't work if the sender is off. It's just like adjusting the float in your commode tank.
One thing that cause this could be the fuel tank is not mounted at the same angle as it was in the Bronco II. And most all stock fuel gauges have their little quirks, such as hanging on full for most of the fuel usage, and then suddenly dropping for the last 5 gallons. My priority for my trucks is it reads empty accurately.
I believe your only option is the other poster's suggestion to take the sending unit out and run it through it's entire range to make sure it does operate the fuel gauge full scale. If it does, you may indeed need to bend the arm, and you also may need to cut the arm shorter to give it more travel.
Just make sure when the float arm is all the way down on the lower stop that it reads empty on the gauge, and that it's a inch or two above the fuel suction pipe. This will give you a 2 or 3 gallon reserve before you really run completely out of fuel.
Take your old in-cab gas tank and measure the resistance, empty, full, just turn the tank over if it is removed.
This will help to see what the gas gage is looking for in terms of resistance, full to empty.
Then ask the Jeff what the ohms range of the sender was that you bought from him.
I also would fill it 2 gallons at a time to see if the gas needle responds equally across the range and to see if the float is moving.
Thanks for all of the information. I emailed Bronco Graveyard for the ohm range on the aftermarket sender that I purchased, so then I can order the correct Auto Meter fuel gauge. Since I have access to a hoist, I will lift the box off again. That would be easier than dropping the tank. I also have to make a better vent because the tank fills slow.
70's fuel sender works from 10ohms full to 73ohms empty. Don't know about the BroncoII.
The ohm meter on the Bronco II sender is 10 ohms full and 73 ohms empty. I just received my Auto Meter Pro-Comp Ultra Lite fuel gauge from Summit racing today. It will be installed this weekend.
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