The Stovebolt Site Forums The Shop Area The Electrical Bay fuel gauge wont budge...

haven't had a working fuel gauge since i bought my 53 truck. took the bed off and have easy access to the fuel tank. i decided to get a new sending unit and replaced it. hooked it up and still no change. i have a 12v system. i did install one of those additional equalizer thingamajigs directly to the gauge, and so far nothing.... Im ready to get my bed back on, but i want to finish this issue first.

Suggestions? thank you guys!

As you know, you should match the ohmage on gauge to sender (30 or 90) If you did that you don't need the thingamajig. Whatever that is. Pot? The number one cause of problems is the ground. Assuming you have a matched ohmage system, ALL grounds must be checked. Think of what it takes to get the sender ground to the gauge. Sender to frame, frame to body, body/dash metal to gauge, engine to body, battery to engine. Bunch of good, clean, metal to metal grounds. You can run a temorary test wire directly from sender to gauge and a convienent ground just to be sure it works. This can be done with sender and gauge on the bench if you want.

the gauge is original so i assume.. 30? and the sending unit is a 30-90 unit. the thingamajig is an electronic voltage reducer which was suggested to use (purchased from lmc). however, all of the gauges are original which i would think they would all need a reducer, yet they all work aside from the fuel... Suppose first things first is try to run a direct ground line to see if i get anything and then go from there. Appreciate the direction!

Safety Comment: Do not measure Resistance (ohms) while a circuit is hot. Now, not sure what a 30-90 sending unit is, so hard to advise. Seems like you have a voltage reducer to reduce 12 volts to 6V for the gauge. They sell 30 Ohm senders and 90 Ohm senders. What is a 30-90 sender? Hopefully you bought a 30 Ohm sender for your 30 Ohm stock gauge. 90 Ohm was not used until 1967. If you have a voltage reducer hooked up properly and a 30 Ohm sender and a 30 Ohm gauge and they are both in operational condition. It's the ground. So isolate this little fuel gauge system from all of the truck wiring and test. Use a fuse inline while testing and, of course, hook it up right!

Where did you put the voltage reducer?

On which post did you connect the sender lead to the gauge (behind the F or behind the E)?

Your sending unit is a "30-90 unit"? Where did you buy it and what is the part number?

If you have original gauges, the fuel gauge is the only electric gauge.

If you disconnect the lead to the sender (at the gauge), the gauge should peg to Full (with the ignition on) - if it is a properly installed good gauge.

Depending on where you put the "direct ground line" you might get different results. If you disconnect the line from the gauge to the sender, the gauge should peg to Full (with the ignition on).

http://www.classicparts.com/1947-53-Gas-Tank-Sending-Unit-Original-Style/productinfo/23-523/

so this is the sending unit i bought. it is a 30 ohm. the voltage reducer is on the right terminal if you were looking at the back of the gauges. i will have to do these recommeded checks you guys have suggested. i will let you know! thank you

Where is your tank located?
That sender is for the behind the seat tank.

The tank had been relocated to under the truck bed. Eventually I'll make that original; another project another day. So I went through the wiring and fixed the backwards connections, replaced wires etc. I've got life in the gauge! However....when the sender unit float is raised to a "full level" the gauge will read close to empty. When the sender unit is all the way lowered as if it were "empty" the gauge reads 1/2 full. I cannot get it to go any higher than that so two questions lie on the table. How to get the gauge to read the full spectrum, and is there a crossed wire/backwards that would make the sender unit read that way? Thanks guys! Ps if pictures of things would help I could provide.

Yes, post pics

I'm not sure if the sender you linked above will work with an under bed tank.

Maybe someone who has that type of tank can advise.

I'm simply bench testing the unit and getting these results. It's 30 ohm unit to an original gauge with a voltage reducer attached. The tank shouldn't play in to the equation or what's happening at this point. I figure I will have to bend the arm on the sender unit to get a more precise reading per the tank, but I need it properly functioning first.

for your bench test make sure you ground the sender and the gauge

you can test the sender seperatly to make sure its is good
...click...

then test with gauge
...click...

i really appreciate it if you just made those videos for this. i will get the meter out and try that. im wondering if it is in fact my guage as it is verrrrrry sluggish when it moves at all.

Chances are your original gauge is bad, but your bench test will verify it.

If you do purchase a replacement gauge I suggest test it also. There have been post here of new gauges being faulty.

I made those videos A while ago when I was going through the same issues you have. My problem was not having a proper ground because I painted the inside of my gauge housing.

Got it figured out with the help of the folks on this forum

Also try the test Tim tclederman suggested earlier
And as bartamos posted. Check your grounds

Good luck

will def try. how can i for sure confirm that my gauge is "faulty"..?

Your test should confirm, inspect the gauge for damage.

So the sending unit is fine. The gauge though isn't. I cannot get it to go from empty to full. Only to 1/2. And it is still registering backwards.. Guess that means new gauge time...

DADS50: Your video is hard to watch twice. Your Dad would be proud of you and his grandson and his 50. Handy: If you have an ohm meter, check the sender, WITHOUT power, by it's self as DADS50 shows, to see if it goes from 0 Ohms to 30 Ohms just to be sure it's OK.

bart, did that and its good so it has to be the gauge.... going to at least rewire everything from the fuel tank with the sender unit installed so i can install the bed. then ill just wait for a new guage.

Dads50: Your video is hard to watch twice. Your Dad would be proud of you and his grandson and his 50. Handy: If you have an ohm meter, check the sender, WITHOUT power, by itself, to see if it goes from 0 Ohms to 30 Ohms just to be sure it's OK as shown by Dads50.

thank you bartamos


Handyguy
did you remove your gauge from the truck for your test?

i didn't remove the gauge completely, no. i just unhooked the leads to both of the gauge terminal posts and hooked up the meter to test. at this point, it can't be the sender unit. i ran new wires before placing the bed back in, so im just waiting for a new gauge to come in the mail. it was the original gauge so it had a good run :-).

I've been reading with great interest.
If I may jump in with a question.
I have a 50 1/2 ton
tank still behind the seat
converted to 12 V generator
2 different 12 gauges one brand new.
2 different fuel senders 1 brand new
Trouble has always been that when I power up, the fuel gauge moves from about 1/2 to E.
Even on the bench. Sender measures correctly from .5 to 30 ohm bottom to top.
Don't know how to test the gauge.
Read above about the good gauge ground and just bench tested it with an additional ground from battery to gauge case.
Testing from 12+ to 12+ side of gauge, S to sender center post, ground from sender housing to - battery post and additional - battery to gauge housing.

Always the same result. Gauge needle moves from 1/2 half to E when powered up. No matter where float is.
All suggestions welcome.
Thanks