The Stovebolt Site Forums The Shop Area The Electrical Bay Gas Tank Sending unit

Hello good people,
My question is about the sending unit in the gas tank of my Chevy 1953 3100 1/2 ton. My gauge doesn't work and I am not sure about what to do first.
It's been converted to 12 volt.
How many ohm's does the sending unit need to be? and is there a difference in the 6 volts and 12 volt units in the tank? and can I test it by shorting the hot wire to the body to test it to see if the gauge on the dash works? Not sure here?

Always many thanks

The "gauge doesn't work" how?

The sending unit (6 or 12 volt) is zero ohms empty and 30 ohms full.

Quick troubleshooting involves ...

... if the gauge reads full with a less than full tank ...
....... remove the wire at the sending unit
....... with the key on touch the wire to a good ground
...........if the gauge goes to empty the sending unit is either defective or does not have a good ground
.......... if the gauge stays full
.............. use a jumper wire to ground the terminal of the gauge to sending unit wire on the back of the gauge
..................if the gauge goes to empty the wire from gauge to sending unit is faulty - replace it
..................if the gauge stays full the gauge is bad

... if the gauge reads empty with more than an empty tank
....... remove the wire at the sending unit, turn the key on
.......... if the gauge goes to full the sending unit is bad - replace it
.......... if the gauge stays empty remove the wire from the back of the gauge that goes to sending unit
.............. if the gauge goes to full replace the wire from the back of the gauge to the sending unit
.............. if the gauge stays empty
................. check for 12 volts on the other terminal on the back of the gas gauge
.................... if 12 volts, the gauge is faulty - replace it
.................... if not 12 volts go find out why

BTW, Phil (Phak1) posted this tech tip on troubleshooting gas gauge problems that I should have thought of before posting all this.

Id remove the sending unit and inspect. Outside of the tank, hook up the hot and have a ground ready.
Turn the key on touch the ground wire to the top and see if the float arm will change the reading and if its accurate or not.

If you need to replace the sending unit I've had excellent results with a 0-30 ohm sender sold by a seller on eBay whose ID is renbusan. It is about $30 delivered and the design is far superior to anything else out there.

Jon, do you have any more contact information for Renbusan? No sending units come up on ebay with him listed as the seller when I do a search.

Was Renbusan's adjustable?

I found one being sold by a seller called "Industrial-stuffs". Definitely sounds oriental.

https://www.ebay.com/itm/261122347319

Ok. I clicked the contact seller button and his name came up as Renbusan. So, it's the same guy but his seller name is now Industrial-stuffs.

Unfortunately his sending unit doesn't come up in a search for a specific make or model sending unit. You have to find it in a roundabout manner. It's listed as:

Fuel level sender sending unit, GM type, 0-30 ohms, 6"-24" adjustable

Here's a link to his ebay store:

https://www.ebay.com/str/industrialstuffs

Yes it is adjustable for length/depth and he provides a chart. That is the one...was designed in the 90s by a gentleman in Taiwan and is a very good design...will last and stay accurate longer. I didn't know he changed his ID, but thanks for letting me know. For the record here is what I like about it:
it wipes along a flat surface (the arc sweep ones fail much sooner)
the resistance material does not get wiped but is cast to the side where it isn't stressed
the wiping surface is actually tiny pieces of metal that have been set into the body of the sender so it will be a very long time before they wear out
it is accurate.

I think it's a bad idea to try to rewrite or paraphrase the Phak Tech Tip. It's good and been tripple checked. We should just link to it or advise to go to Tech Tips.

Note to Wade:
1. The sending units are not voltage specific.
2. I know you know this but you used the term "hot wire"....that always means a wire that has voltage. Which you never ground to chassis.
3. Follow the Tech Tip and post any questions about it or your results.
4. Use the sender Jon G recommends if results show you need a new one.

Which wire are u referring to in your help, the ground wire on the sender or the sender wire on the post screw n nut on the sender unit