The Stovebolt Site Forums The Shop Area General Truck Talk Fuel sender float

I'm going to install a new float on my fuel sending unit tomorrow, I've had the truck for a year now and the gauge always read FULL. I tried all wiring checks etc. and then thought...why don't I look at the actual sender. I unscrewed the unit, pulled it out and looked into the tank with a flashlight. Well wouldn't you know it, the darn float was lying in the tank!
I tried numerous ways to get it out but to no avail. I ordered a new one and now my question, on the end of the sender is a long stiff wire rod that has a circular shape to it, not quite 360 degrees, more like 270 degrees (I'm guessing here on the actual degree of the circle) anyway, how does the float actually attach to this "arm"? Does it just push in, slide in, does the circular shape on the float arm go around the float?
Thanks. Brad

https://fillingstation.com/catalog/flippingbook/index.html#338/z

In the picture you'll see a groove around one end of the float. Snap the sending unit wire into this groove.

you read full with no float on the sender?

maybe time to replace the sender?

I see that mine looks like part #FS889. In the picture in their catalogue it looks like the "arm" hooks around the float from over the top of the float, does it matter if I hook it over or under the float?

If your float was laying in the bottom of the tank, that would make your gauge read empty all the time. The wire "float arm" would always be down , or in the empty position.

Well its been reading FULL all the time, until I noticed the float wasn't hooked on.
When I had the sender in my hand, out of the tank, ignition on and moved the arm, the gauge moved between EMPTY and FULL whenever I moved the arm.
I see your point delux54panel and it makes sense. What the heck is wrong here??? This is driving me crazy.
Brad.

Do you guys think I should just install the new float, put it back in the tank, screw everything back in, hook up the wires and see what happens?
Brad.

Yes.

A Good way to seal the float is to dilute epoxy with acetone and paint the float with it.

Full on the gauge is max resistance by default. Your gauge showing full when it should have been showing empty indicates an open circuit (broken wire, dirty connections, bad ground).

Be sure to ground the sending unit to the frame, not the tank. Use one of the mounting screws of the sender as a point of ground.

Orientate your float on the arm so that it does not hit the side of the tank when installed. There is a picture of the complete unit in the catalog linked above.

I don't know how many years used the same sender but on my '38 it only goes in one way. The mounting holes appear to be equidistant apart but are not. If you try to mount it any way other than correct all of the screws won't go in.

Ok I have just been working on this darn thing and here is what I found:
I took the sender out and took off both terminals, one was attached to one of the mounting screws that holds the sender in, I'm thinking this is the ground.
The other terminal attaches to the center post of the sender, I'm assuming this is the power wire.
With no wires attached to anything, I turn the key on and the gauge goes to full.
If I turn on the key and touch the power wire to anywhere on the tank, or any other metal part, it will move the gauge to empty, this is without it even attached to the sender! As soon as I take the wire off of any metal part it goes back to full.
So am I correct in thinking its a "power wire problem"?
I HATE ELECTRICAL PROBLEMS!
Brad.

The wire that I am assuming is the ground, the one that was secured under one of the mounting screws of the sender, goes to the frame and I've made sure it is tight and clean.
Brad.

Think about it. The current from your hot wire goes to your sending unit then to ground. The amount of current going to ground depends on the amount of current allowed through the sending unit. That differing amounts of current is controlled by the position of the rheostat in your sending unit. An empty tank allows nearly full current to pass. A full tank allows little current to pass. Touching your hot wire directly to ground is the same as the sending unit float being in the empty tank position so your gauge reading empty when you do that is not abnormal.

When you touch the power to gnd it's the same as the float going down in the tank. As Tiny said above, default is max resistance and gauge shows full. That's what you see when nothing is attached to anything. You said before that the gauge moved when you moved the sender's arm up and down when you had it out of the tank If it went to full when arm was up and moved to empty with arm going down I don't see there's a problem. Any loose connection during the year you've owned the truck could cause the "Full" condition and you "fixed" it while removing the sender and testing it. I say press on!

I was mistaken when I posted the part earlier where I said when I had the sender out and moved the arm it would make the gauge move from full to empty and back.
If I run a wire directly from the back of the gauge to the sender, should it read anything on the gauge?

That is not a power post
That wire goes to the "F" post one the gauge

If you have your sender out and a meter you can test it by setting your meter to ohm

When you move the arm up should read 30 ohm
Arm down should read 0 ohm

Thanks everyone for the help...I'm done for the day. I may try again tomorrow.
Brad.

Still haven't had time to get back to this...I need to do the OHM meter test. I'll let you know what I find.
Brad.

Dad's 50. Where/how do I hook up the OHM meter?
Brad.

Hi Brad,
I'm not Dad's 50 but with the sender out and not connected to anything, you hook one lead from your ohmmeter to the center terminal and the other lead to the body of the sender (one of the mounting holes will work). with your meter on the ohms scale you should see the meter go from 0 ohms to about 30 ohms when you move the arm. it doesn't matter which meter lead you use for either connection because you are just measuring resistance which is not polarity sensitive. Hope that helps.
Best regards,
Les

To add to the good description above

...click...

What DADS50 says. Nice video!

I don't know what kind of ohmmeter Cadee has but he needs to pick an ohms scale on the meter such that 30 ohms has some resolution. 100 ohms would work good but if 1M ohms was selected the sensor would appear to be shorted.
Les

Wow you guys are AWESOME!!! I video too...I cant thank you enough.
Unfortunately I wont be able to get to check it until Saturday morning but I will let you know what I find.
Again, thanks very much!
Brad.

ok I just tried it like in the video...I get no readings at all, whether I move the arm up or down.
is there anything else I can test with the ohm meter to see if it is actually working?
I have settings on my meter of: 2000k, 200k, 20k, 2000 and 200...the last two don't have a K behind them. I tried every one of these settings and still nothing.
time for a new sender?
Brad.

Sounds like a bad sender to me.

Brad,
I think cletis is probably right. sounds like your sensor is toast. is your meter working correctly? 200 without the K is the range you should be using. if you short the two meter leads together the meter reading should go to 0 or very close to 0. If that isn't happening then your meter or meter leads have a problem. good luck!
Les

I tried my meter like you said and it does read "0" so...I am ordering a new sensor.
ill let you know in a few days if this solves the problem.
Thanks to everyone that has been trying to help me, I appreciate it very much!
Brad.

I finally got the new fuel sender installed today and everything works great now. The gauge works...the only trouble is I cant use the excuse " gee honey, I ran out of gas, I guess we'll have to park here until a tow truck comes...but that could take hours!"
Brad.

Never think of running out of gas as a bad thing.
Think of it instead as an opportunity to enhance your survival skills.
Above all, do not let your wife know what happened. Do not trust your offspring. They will rat you out. Like, "Hey Mom, guess what Dad did again?"