Fuel gauge moving erratically help!

[1972SUPERSB]

I have a 1998 chevy 1500. My fuel gauge needle has been shaking back and forth for a while. Now sometime it moves all Over the place, to half, full and empty. What could cause this? Has anybody had this problem before? Any fixes? I'm thinking either the gauge is going out or sending unit.
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[75ChevyGuy]

My guess would be the sending unit. But it could also be a loose connection at the connector of the fuel module, or possibly a wire that has been chaffed along the frame rail.

[KQQL IT]

My 2500 crew needed a new sweep on the sender was availible from Gm.
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[1972SUPERSB]

Originally Posted by KQQL IT

My 2500 crew needed a new sweep on the sender was availible from Gm.
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New sweep? Like a new float on the sending unit? Is the sending unit and fuel pump one piece?
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[75ChevyGuy]

If yours is a 98 then I would have to say yes. I believe its all one in one (pump and sender, and sending unit).

[speedygonzales]

Mine has been "blurry" for a few years now, in my case, it's the gauge in the dash.

[1972SUPERSB]

Anyone have any more suggestions. Looks like it pretty common for the fuel gauge to do this. Some say it the stepper Motor some say sending unit. Any more info would help. Just wondering if I should replace sending unit or cluster? Just don't wanna waste any money if I don't have too.
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[speedygonzales]

If it's the fluttering that makes it look blurry, I know it's not the sending unit. In May I did the sending unit for another problem and it did NOT change.

Also if you notice, as in my case, the needle reads the correct level and moves up and down as the level goes. That is also not an indication of the sending unit.

Any question and you can disconnect the sending unit and place a resistor in the connector that corresponds to the resistance value of the mid way point of the tank (as if the sending unit were connected).

In my case it's the gauge pod. I highly doubt (if your symptoms are like mine) that it's anything else. The problem with JY parts is you don't know if that one would have the same problem.

If however, your needle is moving like it's full one minute and lower the next, it could be the sending unit. But, more likely it's a wiring issue like a poor connection. Particularly if you noticed the level going down like it should as you drive then suddenly it's higher. A sure sign the connection quality is poor.

The resistor trick could probably find that too.

[1972SUPERSB]

Mine gauge is just not working now. It will read full when I fill it up then stop around 1/2 mark so I never know how much gas I have. Prob try sending unit first since the gauge isn't working now.
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[nickvig]

I have the same problem on my '98 RCSB. I swapped gauge clusters with one from the junk yard and it still fluttered. I tore the stepper motors out of another cluster, put them into the extra cluster and it still fluttered. My gas tank is out right now as I'm dropping the truck. When I get the new fuel pump / sending unit installed and the truck is back on the road I'll let you know if it worked.

[1972SUPERSB]

Originally Posted by nickvig

I have the same problem on my '98 RCSB. I swapped gauge clusters with one from the junk yard and it still fluttered. I tore the stepper motors out of another cluster, put them into the extra cluster and it still fluttered. My gas tank is out right now as I'm dropping the truck. When I get the new fuel pump / sending unit installed and the truck is back on the road I'll let you know if it worked.

I am waiting on my sending unit to come in as well. I will let you know also when I get it installed if it fixed my problem.
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[RayInAlaska]

I had a similar problem with the gage on a 1994 Suzuki Sidekick, and the fix was as follows: I cleaned the wire terminal that connects to the sending unit, and while being very careful I made the terminal tighter by carefully squeezing it with a needle-nose plier when disconnected. I squeezed it close a little at a time until it was just right (took several tries).

[mygmctruck]

I had the same problem and others issues with my dash gauges.. After tearing down the gauge cluster , I found a short in my printed circuit.

[1972SUPERSB]

I just replaced my sending unit. The gauge works correctly now which was my main concern so I will know how much gas I have. The Fluttering is still there, not gonna worry about it too much since the gauge is reading correctly now,

[Boog]

This is timely in that just yesterday on MotorWeek tv the garage segment was about fluctuating fuel gauges. While some sending units do go bad and some electrical connections are the root of the problem they said the fuel can also be the cause of the condition. High sulfur content of some fuel causes corrosion on the reostat. I forgot what product he suggested trying before diving into a pump assembly replacement. Lots cheaper and easier to try it first. I bet a search would turn up a brand.