The Stovebolt Site Forums The Shop Area The Electrical Bay Fuel tank sending unit adjustment

Any way of adjusting the sending unit level other than just bending the arm/rod?
Mine appears to be off by about a 1/4 tank.

I did have a tiny pin hole in the float, dried it out and used a small bit of
J-B Weld (for fuel tanks) worked great.

I had the sending unit out but didn't think to look for any type of adjustment,
I've done it 100 times on toilet bowl floats but, ...jus thought I'd ask before pulling it out and bending.

thanks, Jim

What year truck?

'50 3100

Same adjustment as toilet bowl floats (you can't really find the lever type anymore, as the fill valves have all gone plastic). The old brass floats are a thing of the past.
Remove - bend arm. Reinstall. Test. Repeat. Repeat.......

I would pull the sender and test it with a meter.

0 ohm empty, 30 ohm full

Being off 1/4 tank is pretty drastic
Replacement senders are not very expensive

Might be someting else going on, check the ground wire and sender wire.

I agree with DAD50. Test the sending unit/gauge out of the tank to make sure that when the float is all the way down, the gauge reads empty. Then you can bend the wire so the float is higher than what it is currently.
Carl

Thanks for the advice guys,

pulled the sending unit out,
checked good,,,0 ohm empty, 30 ohm full.

adjusted the arm to where I thought it should be, reinstalled, ...still not right.

took it back out, connected the wires (without) installing and moved the float up & down,
I noticed when moving float (full) up, gauge only registers 1/2 full.

As soon as I manually move the float to lower, the gauge begins to move down.
checked (all) wire connections.

?? Bad gauge or is this adjustable?
thanks again, Jim

When you reconnected the sender out of the tank for this test did you ground it?

Did this gauge work before?

?? I grounded the wire to the unit,
In other words, (2 wires), ...one to sender, other to sender body.
Entire sending unit setting on the truck seat.

You have established the sender is good with yourr ohm test

If the ground wire is clean in tight then the problem is with the gauge
Is it a new gauge? Did it work before?
Was anything disturbed at the gauge?

I do love this forum, you guys have been a tremendous help. I’m still scratching my head
with this, so maybe you can still give me some direction.

Here’s what I can relate…
1) ’50 3100
2) Converted to 12v system.
3) Fuel gauge is 6v.
4) Entirely new wiring harness.
5) Gauge is original (as far as I know).
6) Gauge has always worked (for me).
7) But I don’t know if gauge ever worked accurately .
8) I’ve never paid attention to it, never had more than a couple gals in it.
9) Sending unit is 30 ohm, …”30 ohm” stamped on unit.
10) Checked Sender with Ohm meter, checked good at stops …0 ohm empty, 30 ohm full.
11) Float Rod moves freely “stop to stop” and is basically straight (as found)
12) Float is completely buoyant.
13) I’ve made every effort to loosen & re-tighten all electrical connections.

I’m working on the assumption that I have it all wired correctly because
it appears to be functioning correctly except for the fact that when I move the float manually
to the full up position, the Gauge only registers 1/2 full.

From the full up position (of the float) the instant I begin to move it (from full up),
the Gauge begins to move down (from it’1/2 full position).

Now, (for reference) let me back up just a bit, before doing these tests
with sending unit installed in tank and tank is 3/4 full, Gauge registers 3/8 full, as in photo "C"

Returning to the “bench test”;
while doing these tests, the sending unit was setting on the seat of my truck,
the only (2) wires connected to it were the same as it is in photo “B”,
1 wire connected to the terminal fitting/stud and the other wire connected to the sending unit flange.

Again….it appears to function properly except that for full up travel of the Float,
the Gauge only registers 1/2 travel.

Can’t think of anything I left out,
I don’t know what else to do, maybe you can help…. I’m all ears.
Thanks, Jim

Sounds and looks correct

Ive never used a reducer, is it touching the gauge housing? Is it suppose to be insulated?

I see you put a new decal on the gauge, could the sticker be impeeding the needle? Could the bezel be hitting the needle?

The ground wire comming off the sender flange, where dose it ground? It the connection clean and tight on the other end



If you turn on the truck and remove that sender flange ground wire quickly the gauge needle should jump to full

Could just be a bad gauge

Are you reading 6V at the gauge end of the Runtz voltage reducer?

Thank y’all for sticking with me on this,
I could hardly wait to get out and try your suggestions…

Needle does not touch glass nor refurbished gauge face.
Disconnecting the wire at the sender flange does send the needle to Full deflection.

Now here’s something I found strange…
And I repeated it “a hand-full” of times to make certain I was seeing what I was seeing.

With the Sending unit installed in tank:
When I would disconnect the wire at the sender flange and then re-connect it
and then turn On the ign key….the gauge needle would now go to exactly 1/2 full.
When I turn the key Off and then back On….the gauge needle then goes to exactly 3/8 full.
I’m going crazy, I did the above sequence 4 or 5 times and every time… I got the same results, 1/2 then 3/8, 1/2 then 3/8......

So now I thought I’d check one of the other possible issues,
....“is the voltage reducer possibly touching the instrument cluster housing?”
(here’s where I get [censored])
In an effort to slightly pull the Voltage Reducer away from instrument housing…..the Reducer broke in half !!

you know, sometimes the simplest job turns out to be the biggest headache.

Jim

No need to check the reducer's output now. A new Runtz cost about $20

Ha, I hear ya.

Do you think that reducer was hitting the rib on the back of the gauge?
You could stand it off with some washers


Your first needle test where the needle went to full proves the needle is not pinched, it would not hit glass. It would hit the bezel if it was


Im a little confused on your second test where it went to 3/8
Compared to when it went to full

DADS50,
in photo (A), it looks like it could be touching the rib on the back but there is a "blob" of plastic on the back of the Reducer that kept it off.
Also (with ign key On) I pulled on the Reducer a bit to confirm it was not touching and there was no movement of the Needle.

Once I confirmed that, I had to jus' keep "messing with it".....and broke it. (can't leave good enough alone)
So I ordered another Voltage Reducer.

you posted......Im a little confused on your second test where it went to 3/8
Compared to when it went to full

? just to re-affirm, 3/8 full is with it all wired up.
Full is with Sender Flange wire disconnected.

I watched your YouTube video, very nice tribute.

Jim

Thanks for your comments,

Im curious what your sender is putting out installed in the tank
If you have 3/4 tank of gas in there you should read about 22 ohm at sender post.

If you can , disconnect the brown wire at the sender and take an ohm reading at the post

20 at the post with wire disconnected

As long as you have 20 ohms at the other end of that wire at the gauge you can elemnate the sender as a problem

To test the other end of the brown wire youll have to disconnect it from the gauge and meter it.

Above someone suggested seeing if the reducer gave you 6 volts at the gauge
When you get your new reducer you can meter it before you hook it up


Is the black wire off the reducer a ground wire?
Ive seen this style before
...click...

Ignore the connections in that pic. It was from a member who wanted to know if he hook his gauge backwards. It is in that pic
But you can see the reducer can be installed and be out the way

Thanks for the "Click" photo, that's the style Reducer I ordered, I'll install mine that way too.
I'll do those test when I get it, and also trace-out and verify continuity of the Sending unit Flange wire.

OK, got the new 12v Reducer today.

Checked Volts at (gauge) wire ends (gauge disconnected) ….showing 12.1 volts
Checked Ohms at Sender (wires disconnected)….showing 18 Ohms.
(I’ve driven the Truck some since earlier posting of “20 Ohms”)
Again checked Ohms at Sender (wires connected)….also showing 18 Ohms.
Traced Sender Flange (black) wire…it is securely grounded to Truck Frame.

Here’s something that’s got me confused,
Checked Ohms at (gauge) wire ends (gauge disconnected) ….showing 60.1 Ohms,
is this normal or do I need more trouble-shooting??

With everything wired up and the ign key on,
Gauge is showing ½ needle below ½ tank, but at 18 Ohms it should be above half.

?? Bend the (Float) Rod slightly? or am I jus’ being Anal and I should leave the thing alone?
But the big question is ….what’s with that “60 Ohms” ?

Shouldnt you be reading 6 volts at the gauge?

WOW, What was I thinking, I can't believe I missed that!

I went back and checked and rechecked...yep, 12.1v
Then I was thinking, I didn't see any instructions or arrow indicators but maybe the Reducer has a specific flow direction.
So I turned it around and checked again....12.1, even tried a different voltage setting on my multi-meter....still 12v.

This is the gauge that was in my truck when I got it, and it was a 6v system, so I have no reason to believe that this gauge is anything but 6v.
Now my question is...turning the ign On, wouldn't the Gauge be fried? (12v going into 6v Gauge)
I turned it Off & On a dozen times, leaving it On :20-:30 sec at a time,

...I'm lost

You have two leads going to the E-post on your fuel gauge.

I think the only lead that should go to that post is the 12v lead on the output side of the Runtz-style reducer (a 6v output)

What are the two leads going to the E-post?

tc,
I think you're referring to the (earlier) Reducer at the beginning of my original post.
THAT Reducer did have an add'l wire (ground). I accidentally broke that Reducer, I now have the same Reducer pictured in DADS50 post at the top of this page (page 3).
It only has one wire to Reducer connected to E-post (12v hot)

OK, as long as the reducer is connected to the Empty post.
And, your sender top is grounded?

Tim,
Both of your statements are correct with respect to the way I have it set up.

What my issue is, I have 12v coming OUT of the Reducer, should be 6v. (It's a new reducer)
and why hasn't it fried the Gauge?