gas gauge dont work help

[bigblock79]

gas gauge dont work. it lays past full and never moves what do you think it is 1973 chevy truck thanks

[C-10volvo]

this is a fairly common problem in all 73-87 trucks. since the gauge is still working (not resting at wayyy empty) it is most likely a connection issue. take your dash apart and check the two connectors behind the gauge. scrape away any corrosion and pinch the two tabs together to get a tighter fit. if that doesn't cure it, its the connection at the tank and it will have to be dropped to mess with. hope that helps.

[67Cowboy]

Someone correct me if I'm wrong but all the wire going to the tank does is act as low draw ground. If it gets knocked off (ie. mud ball) your gauge will read past full until you restore that little tan colored wire back to the sender post on top of the tank. You should be able to see it with a flash light.

[bigblock79]

there is a brown wire coming off of the tank but is not hook up. they are no were to hook it up. they are some wires coming pass the alt going to the starter. it is 2 brown wires and a black one that is not hook up. i took a wire that i had and wire it to the brown wire coming from the tank and hook it to all 3 wire at diffrent times and did not work. i found out the truck had a extra tank at one time or another the fuel tank switch is under the front seat on the driver side and is not hook up. it only got 2 fuel lines about 1 foot long on it. they are one more wire coming from the fuse box going over the motor and it is brown i hook it to my wire too and it still don't work. please help i need a gauge

[bigblock79]

ttt

[67Cowboy]

OK, Bud I know how aggravating this can be and I thought I had read a thread on the subject in one of my truck clubs or a vender site but I haven't found it yet; and here's a couple of pages from my GM service manual.

[67Cowboy]

next page.

[shrtbx]

Im actually having the opposite problem. I fill up the tank needle wont come down from full until i burn off a half a tank. Is it possible i have a bad gauge as well?

[67Cowboy]

Those are from my 1974 GM Service repair manual, I also have the '76 supplement and I didn't find a thing in there about problems with the sending unit or wiring but almost everybody said make sure the ground from the sending unit to the frame is hooked up because the sending unit is very sensitive . Here are a few links that may help also, I tried researching this site but so much stuff gets deleted here and photos disappear . One of the threads has the OHMS for all GM Models and there are some good info on the others. I have been meaning to do some research on this for myself so since I was off I thought now would be a good time for both of us, as I'm putting a 30 gallon Van tank in my '67 and needed to know the differences in my gauge and the sending unit that came in the 80's Van tank before I hooked it up and had trouble.
http://www.chevygmcofkc.org/forums/s...l+sending+unit
http://www.webrodder.com/article.php...11&SID=60&CID=
http://www.performancetrucks.net/for...earchid=815144
http://www.nastyz28.com/forum/showth...ght=fuel+gauge
http://www.egauges.com/Cla_Inst.asp?CP=Fuel.htm
http://chevelleengineer.home.comcast...r/fuelgage.htm
http://en.allexperts.com/q/Chevrolet-Repair-808/
http://www.camaros.net/forums/showthread.php?t=73968
http://www.wheelscene.com/default2.aspx
http://www.chevelles.com/techref/ftecref18.html

[boxrodz]

bigblock79,
If your gauge is reading past Full, i.e. 3 o'clock position, then you have a loose (open) connection between the gauge terminal and the sending unit to Ground. It's likely the ground wire coming from the sending unit to a point on the frame near the tank. Be sure that it is grounded to the frame. I've included a link (http://67-72chevytrucks.com/vboard/s...d.php?t=249369) that shows a schematic of the wiring for a dual tank setup for a 1983 model. But, other than the dual tank setup and the wiring color code, you should be able to use it to understand the wiring on your 73.

[Captkaos]

Check the sender to frame ground wire as Boxrodz said.

[boxrodz]

Originally Posted by shrtbx

Im actually having the opposite problem. I fill up the tank needle wont come down from full until i burn off a half a tank. Is it possible i have a bad gauge as well?

shrtbx,
It's possible, but it may also be the sending unit. To check out the sending unit, disconnect the signal wire coming from the sending unit and attach it to the Postive lead of a ohm meter. Ground the Negative lead of the ohm meter to the frame. The meter should register between 0 an 90 ohms. If the tank is past half full, it should register closer to the 90 ohm reading, i.e. 45 ohm to 90 ohm range.

If that checks out, you can use a potentiometer to test the operation of the fuel gauge. Basically, disconnect the signal wire coming from the fuel gauge and connect it to one of the three terminals of the potentiometer. Ground the variable terminal of the potentiometer to the frame. As you vary the potentiometer from 0 ohms to 90 ohms, the fuel gauge should register, respectivity between Empty and Full.

[67Cowboy]

Originally Posted by Captkaos

Check the sender to frame ground wire as Boxrodz said.

Like post #7 said

[shrtbx]

im proboably going to have to change both sending units in each tank, becuase im having the same problem when switch to the right tank.

[bigblock79]

thank ya