Chevy & GMC Vans

I have heard that this is a common problem with Astros. My gas guage has a twitch. When I rock the van or take a turn the needle will twitch, sometimes as far as to half a tank, and then return to the proper place. How can I fix this?

Replace the sending unit, if you wish, but I'd leave it alone if it registers correctly.

I've got the same problem and short of replacing the tank, I don't think it can be fixed. Inside the tank the are plastic baffles that help to control the fuel sloshing around. In my tank, those plastic baffles have actually started breaking away. The fuel sloshes more now and the float on the sending unit moves more causing the swinging needle in the gauge.

I first found out about this problem when the van died on me one day and I sent it to the mechanic. I got charged for a fuel pump and they sent me on my way. Half mile down the road the van dies again. they take it apart and realized I had run out of gas (even though my gauge read 1/4 full) Looking further, they found the baffles were breaking apart and had lodged itself under the float arm causing an errant reading. The more those baffles break off, the more the fuel sloshes and the needle fluctuates more.

Or it could just be your sending unit is going bad.... But I'm guessing if it always returns to the proper place, that the culprit is the baffles..

my 99 has had the twitching needle since I bought it. gas needle and oil pressure needle.

now twitching differs from jumping all around from 1/4 to full to half.. etc..

it's the first I've heard of these baffles, and that doesn't explain my oil pres twitch.

eventually (over a year), the gas needle started doing the jump. within 3 months after that it wouldn't read at all one day, then would read correct the next day. then the fuel pump died.

new sending unit with pump was installed and although the needle reads correctly now, there is no jumping around, the twitch (or vibrating as I call it) has been back ever since.

this doesn't help resolve your problem, but know that it's something you may have to learn to live with... as I have.. and I hate when something in a vehicle isn't operating 100% as it should.

The SPB has the vibrating needle on the dash and I did replace the fuel pump/sending unit and it never changed the needle. I have read where there is a fluid in the gauge that keeps it from vibrating and that the fluids leaks out over time. As long as it still reads the correct level, I never messed with it.

yep.. fluid is what I also understood but wan't sure how correct that was

that would make sense to be something gauge related, being that both mine are doing it.. and there's no pump or sending unit associated with my oil pressure gauge lol

You too, huh? I don't really remember when mine started to "vibrate". It has for a very long time, even after two fuel pump replacements. I hate it, but have learned to live with it. It's accurate and does not "jump", but just vibrates within a very small distance on the gauge.

I know the pump will go out again and still would love nothing better than to replace it with an external electric pump. Maybe that too would help the needle vibration.

I'm not sure where the twitch comes from, but it isnt the gauges or the sender. After have a little bit of an engine fire with the doghouse off, and replacing the dash, and the entire wiring harness with a 98 van (from a 97 which has its own module to control the fuel gauge) I have a twitching fuel gauge.

I think its the output of the computer causing it, as the gauge is controlled by the PCM directly now. My sender is new, and worked fine on the 97 electronics. With the same cluster, with the 98 wiring it twitches. With a scan tool, the readout from the PCM is steady, so that leads me to a bad output, or bad wiring in the dash.

I havent gone any further than that yet, but it seems to be common 98 and up. If someone has had this fixed I'd love to know what was done! There is no fluid in the gauges either, they are just air-core gauges..

Scott

My 98 does it as well.

I have it on pretty good authority that the gauges are liquid dampened to prevent the gauges jumping around and that the liquid leaked out causing the gauge to vibrate.

This is a picture of the inside of the fuel gauge itself, not sure where they would put any liquid as nothing is sealed. Maybe I am wrong, but it doesnt appear to be liquid dampened. If they all are, I dont understand why only the fuel gauge seems to go bad. I think there is another reason, just havent found the fix yet. The cluster in my van was fine with the 97's wiring so I am sure its not the cluster itself.



For the amount of people who have this problem I am suprised there is no TSB from GM about it... I dont know anybody with a 98 or 99 without a fluttering gauge!

Scott

It's the stuff in the fuel .Eats up the senders

That's not necessarily true Don. I switched out the fuel pump/sender unit with a new Delco unit and my gauge twitched just the same. I have not hear of anyone fixing this problem yet.

Hey, I have a 97 and my gauge titches as well. Last night I noticed it doing it when I have the signals going, but it will also just swing up and down for other less apparent reasons. I always figured the other movement was as the gas sloshed around in the tank.

The vibrating would seem to be a "ground" problem, while the swinging is most likely the sending unit. Both my '98s have the vibrating problem but so far it hasn't bothered me enough to figure out a fix.

HPbyStan wrote:The vibrating would seem to be a "ground" problem, while the swinging is most likely the sending unit. Both my '98s have the vibrating problem but so far it hasn't bothered me enough to figure out a fix.

Yep ts a ground problem. Maybe in the harness of the sending unit , or wherever it gets it's ground from.