what is a gas tank sending unit and what is its purpose. i asume that it is what sends gas up to the carb, but i dont know for sure.

 

The sender is in the tank and consists of a float and a potentiometer. As the gas level increases or decreases the voltage to the dash unit changes and gives the level.

 

ok thanks. so how do you know if you need a new one or not. would it be if your gas gauge doesnt work?

 

It could be the sending unit, gauge or a wiring issue. I would start with making sure all of the connections/wires are good and connected. Then from there testing the guage and or sending unit.

 

If your going to check the sending unit (i.e. its removed from the tank) look for approx. zero to 3 ohms in the empty position and somewhere between 150to 165 ohms from empty to full.

FYI

Yellow terminal is the empty and gray terminal is full.

You can find the same two wires under the dash to check continuity. That gest you past the tank connection, body connection, and instrument connector.

The guage is more complicated of a test.

Remove battery prior to testing any of this stuff.

 

Okay Thans For The Info

 

I just went through all that. I have a 1960 super 88. Fusick had the best price for sending units. The problem I had was the "sock" filter...
I bought mine through a chevy supplier. http://www.lategreatchevy.com/produc...dept%5Fid=1272
The sending unit is on top of your gas tank. I wasn't getting a reading on my fuel gauge so, I got the sending unit. (USA Auto Parts0 for $129.00) Fusick had the same unit for $69.00!
I dropped the tank (9 gallons of gas, premium still in it) took it to a shop to have it blasted, some shops still can do the "renue" process, they did something callled rattling, a process of shaking beads around to dislodge the chuncks of varnish, etc. Then, the spray an inhibitor.
At Late Great Chevy, be sure to check your size. 5/16 or 3/8
good luck.

 

I just got one of these for my Custom Cruiser. The gas gauge doesn't go below 1/4 tank. Not a big deal but I have to take the tank off to fix some corroded spots anyhow so figured I might as well change out the sending unit too! Was only $35 from Rock Auto...good price.

 

This thread is from 2006.

$35 is a good price though haha.

 

haha...yeah I know...I'm fairly new though and am still getting through all the threads