gas tank sending unit

geraldchainsaw · 2014-06-09 07:52

hi, its been brought up before, i can't find it any where, checking the sending unit on the gas tank, mine will only read around 3/4 on the dash, when it gets around 1/2 i get a little scared and fill it up, does anyone know what page i might find my info on?, how to check dash gage?, and or the gas tank gage?, thanks jerry

RICH MUISE · 2014-06-09 08:12

Jerry..I remember seeing it not to long ago..try this to find it...click on your name/tag on the left and it should bring up a menu where you can scroll thru your old posts..when you see the one you're looking for just click on it.
opps...I thought you were talking about a thread that you were posting on....never mind.

clusterbuster · 2014-06-09 08:22

The 57 Ford repair manual states to turn ignition switch off and connect the terminals of 2 series connected flashlight batteries to the gauge terminals. The 3 volts should cause the gauge to read approximately 1/2 scale. Two cells of a storage battery may also be used for this test. If 4 volts from a storage battery are used, the gauge should read approximately 3/4. Seems as if the gauge is moving, it would be more likely to be a sender problem.
I think if I were doing it, I would buy a sending unit and disconnect the wire from the sending unit and hook the new one to it and try. All you do is take the cover off in the trunk to remove the wire from the sender. The new sender would have to be grounded to try it.

hiball3985 · 2014-06-09 17:04

Another way to test the gauge is remove the wire from the tank sending unit and ground it, the gauge should go to the full side. Checking the gauge with the flashlight battery method is almost impossible unless you have the whole gauge cluster removed

geraldchainsaw · 2014-06-09 18:53

thanks guys, i'll try the one taking the wire off of the tank and grounding it, and then maybe ordering a new sending unit if need be, thanks again, jerry

geraldchainsaw · 2014-06-09 21:13

ok, took the wire off sending unit, ground it out, turned on key, gas gage pegged out, hooked up wire back to sending unit, ground it out, gage pegged out, so i guess i need a new sending unit, thanks for the help guys

hiball3985 · 2014-06-10 07:19

Quote from: geraldchainsaw on 2014-06-09 21:13
ok, took the wire off sending unit, ground it out, turned on key, gas gage pegged out, hooked up wire back to sending unit, ground it out, gage pegged out, so i guess i need a new sending unit, thanks for the help guys

Thats a good indication the the gauge is good. When you pull the sending unit check that the float hasn't been leaking and partially filled with gas. This is a common problem with many old cars that have two piece brass floats that are soldered together. Gas with ethonal in it eats away at the solder..

electricalan · 2014-06-10 19:15

Good call Jim the one I pulled out of the Ranchero was plumb full of Gas gunk and probably weighed 5 times what it should.
Al

JimNolan · 2014-06-11 20:20

Jerry,
When you install your new sending unit, sifin all the gas out and pour in one gallon of gas. Adjust your sending unit to read Empty. Then pour in one gallon of gas at a time and see where the needle goes. Mark down your results for 1/4, 1/2, 3/4 and Full in your owners manual. That way you'll know how much you got left in the tank when it is being used. DON'T expect it to be even reasonably where it should be. The only important area's of the gauge for me is 1/4 and Empty. On mine I drive a half tank of gas out and it's between 3/4 and Full. But the important information I want is around 1/4 and empty. It would be nice if yours worked like it should but I used all new stuff and it still read off. Anyone I've talked to with a 57 Ford didn't brag about the exactness of their gas gauge.

Ecode70D · 2014-06-12 06:36

Quote from: JimNolan on 2014-06-11 20:20
Jerry,
When you install your new sending unit, sifin all the gas out and pour in one gallon of gas. Adjust your sending unit to read Empty. Then pour in one gallon of gas at a time and see where the needle goes. Mark down your results for 1/4, 1/2, 3/4 and Full in your owners manual. That way you'll know how much you got left in the tank when it is being used. DON'T expect it to be even reasonably where it should be. The only important area's of the gauge for me is 1/4 and Empty. On mine I drive a half tank of gas out and it's between 3/4 and Full. But the important information I want is around 1/4 and empty. It would be nice if yours worked like it should but I used all new stuff and it still read off. Anyone I've talked to with a 57 Ford didn't brag about the exactness of their gas gauge.

Jerry
I sure am glad that you asked this question because that was on my mind.
Jim
That's a great answer. That's how I'm going to do it when I install my fuel tank.

hiball3985 · 2014-06-12 06:59

For anyone that needs to replace the brass float Steward Warner makes a nice one that is half brass/plastic? that isn't soldered. I think I got mine from Macs..

Ford Blue blood · 2014-06-12 08:42

Quote from: JimNolan on 2014-06-11 20:20
Jerry,
When you install your new sending unit, sifin all the gas out and pour in one gallon of gas. Adjust your sending unit to read Empty. Then pour in one gallon of gas at a time and see where the needle goes. Mark down your results for 1/4, 1/2, 3/4 and Full in your owners manual. That way you'll know how much you got left in the tank when it is being used. DON'T expect it to be even reasonably where it should be. The only important area's of the gauge for me is 1/4 and Empty. On mine I drive a half tank of gas out and it's between 3/4 and Full. But the important information I want is around 1/4 and empty. It would be nice if yours worked like it should but I used all new stuff and it still read off. Anyone I've talked to with a 57 Ford didn't brag about the exactness of their gas gauge.

I have done this with every car I have built. But....I do it on my saw horses, tank off the car, test battery,gauge and sender hooked up and fill with water one gallon at a time. Some where along the build the tank always comes off the car for "hot tanking" and cleaning. Makes it so much easier to do the filling thing and easy to drain and dry out.

Ecode70D · 2014-06-12 09:45

Quote from: Ford Blue blood on 2014-06-12 08:42
I have done this with every car I have built. But....I do it on my saw horses, tank off the car, test battery,gauge and sender hooked up and fill with water one gallon at a time. Some where along the build the tank always comes off the car for "hot tanking" and cleaning. Makes it so much easier to do the filling thing and easy to drain and dry out.

Ford BB... I'm going out there right now and put it on saw horses and run jumper wires over to it from the car . First I have to make a sending unit gasket. I already made a little dummy plug for the fuel line for testing purposes.
You guys with all these good ideas are OK. Jay

geraldchainsaw · 2014-06-12 13:49

thanks for all the info guys, i'll give a update, i undid the wire to the sending unit, and remounted it, and now for some reason it reads full, or at least the full mark, so for now thats what i'm going to leave it at, as for all the info u have given me when it comes time to put the car away again for the year, i'll take the tank out and give it the 1 gal+ test to check where it goes with each gal put in, thanks again for all the info, jerry

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gas tank sending unit