Question on Gas Guage
 

Does anyone have any info on making these work. I have about 10 of them and they all have the needle at different places on the guage. Are they all broken? I try and align the needle at zero before i put them in, but they never indicate correctly. any help would be greatly appreciated. thanks
john

first of all, how did you come to have 10 gas guages...??? Anyway, I doubt all of em are shot, so you probably need to look at the tank sender and the wiring running to your dash... pull the seat forward and check that the brown wire is connected, and follow it along the floor to make sure it's in good shape... if it checks out ok, you probably have a bad sending unit... good luck.

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'72 short step, 350, 700R4, tilt, ps, pdb, a/c, lowered coils, etc., other work in progress... San Diego, CA
http://www.ixpres.com/vlusardi/chevtrk.htm

sender is new, i guess i kind of just ended up with all the guages from all the trucks i have parted out.
john

kilomanjaro-
they are not suppoosed ot return to E, the needles are free floating not connecte dot anything, they react to energy waves pulling on them there are pole piece type of deals on the needle inside the gause assembly, that variable energy(controllled by sending unit) pulls or pushes on which moves the needle, if you take one apart you will see how it works, you have enough around to take one apart and learn on. thats the only way to learn, and who doesnt have a bunch of gauges laying around ? i thought everyone did ?? and plus dashes from all kinds of other makes and models and years..

good luck!

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Randy- Lincoln, IL
r68c30@hotmail.com
-71 C-10 350/CH465/3.07
-84 Z28 Camaro 5.0L 700R4, 3.73
-84 Firebird SE 2.8L T-5
-82 Firebird 350 4bolt (TBL)/TH350
buy/sell/hoard/trade most any GM vehicle parts of any kind
-parting out: '81 Cutlass Supreme Brougham
*Paint is overrated
© RSS Enterprises 2000

You are not getting power to the back of the guage. If there is no 12V, it won't move at all regardless of the sending unit.

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'69 G.M.C. 350/350. Trying to clean up the left over damage from the Dope-Smokin-Old-Man
I've been dubbed the Longhorn Freak/Fanatic/Expert, I just hope I can live up to it.
FINALLY got the HORNIAC...a '70 one ton Longhorn with a Pontiac 350/350 and lots of 'personality'. Check out The Longhorn Webite.
If you need a pic posted, E-mail me at longhornmail@yahoo.com
Andy, in Columbus Ohio

Kila-
I have similiar probs. Only mine works when it feels like it!! I used to think if it was registering at all, I had some fuel. I ran out of gas 2 weeks ago using this theory!! I have another guage, but haven't tried switching it out. I fear it's the sender!

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67 Chevy C20 LB Stepside,
350 4-bolt with goodies.

I just replaced my sending unit and checked my fuel gage. It is not a hard task. If you are getting readings sometimes and not continuosly then there is either a connection failure or a bad sending unit. the gage reads when there is a signal. I would bet on the sending unit. You can test the gage by doing a continuity check across the leads on the back of the unit. This will flow current and force the needle to move. The gage is bad if it does not move with this test. The sending unit has a copper or brass contact that swings across a linear resistor and this causes metal wear. As old as these trucks are this is a very common failure point. You can also check it with an ohm meter. You should read from 90 ohms to zero accross the resistor. DO THIS CHECK WITH THE SENDING OUT AND AWAY FROM THE GAS TANK. Make sure that both of your crimp lugs on the sending unit wire is solid.
If these things all check out then you should be reading fuel accurately. Good luck.

You may also have a ground problem. I had to run a ground to one of the posts on the gauge itself. I've never had a problem since. That metal backplate has a tendency to rust and after several times on and off, will not fit tightly.

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1970 Chevy C-10 350,3 spd
1998 Pontiac Firebird
1999 GMC Envoy

Harvest,AL 35749

John,

It sounds like you just need to adjust the needle to zero. We have adjusted them a couple of ways. The method that I feel works best is to hook the gauge up and feed the gauge with a known 90 ohm signal. This should have the gauge reading at full. Install the needle at full and then ground the tank wire. When the wire is grounded
the gauge should be reading at empty.

If you don't have an ohm calibration unit you can test your tank sender with an ohm meter to make sure it reads 90 ohms and use it for the reference.

Jim