2003 Impala Gas Gauge

Plastic fuel tanks insulate the sounds better than metal tanks, metal tanks normally have an insulation pad between the tank and body.

Most cars are insulated from fuel tank noise by the rear seat cushion. When driving a car with the rear seat cushion removed while monitoring the fuel pump voltage there is a surprising amount of fuel tank and road noise.

Pick-up trucks with the long narrow tank can produce a “thump” from the fuel tank when approximately 3/4 full while taking off from a stop. The fuel shifts to the rear and slaps the back of the tank, some owners have complained of a failing rear differential on their new truck because of this noise.

“When I got in today the gauge was where given the miles I have driven since fill up should be but as I drove to work if I braked it would move, when I excellarated it moved, When I was at a stop light it would return to where it should be…Maybe I have a ghost in my tank…”

That’s not a phantom in the tank. Those are symptoms of the electrical “wiper fingers” on the level sensor (moving part of the float arm) making intermittent contact because they are compromised.

Speaking of baffles…

I think _@brm7675_is gone now, but not many cars have such easy access to the fuel pump module/fuel level sensor and it really baffles me as to why it wouldn’t be fixed…

…unless this car has been neglected, maintenance wise, or is already a rolling a heap. Neglected maintenance on vehicles can develop a snow-balling result.

I’d be thrilled coming on this site with a problem, getting free meaningful advice, finding out it’s a fairly common issue, and has a fairly easy inexpensive solution, and get it taken care of, but that’s just me I guess.

I’d check with some folks who know these cars well and see if my advice is good and see what it would cost to take care of it.

These 2000 though 2005 Impalas were/are great cars. Look how many are still on the road (and looking good) 12 model-years after the last ones were built.
CSA

Had chance this weekend to put about 250 miles on the car, and the gas gauge issue kinda improved. Now when I first get in and start the car the gauge will show what I believe is the correct reading based on the miles I have driven, however once I start driving it will move up and down and only return to the correct spot if the car is stopped and not moving for a few minutes. My guess is my sensor or something is shot, and since the car is still running fine I guess I will just have to learn to keep close monitor on my fuel usuage.

Could be the gauge or the sensor, hard to say. If the gauge on your car is driven by one of GM’s dash gauge actuator servos of that era, that’d be my first suspect… It’s often possible for a shop to fix that problem btw ; a good shop will usually remove the affected part of the dash to the work bench, and all the old servos are replaced with GM’s improved version. You’d want to eliminate the sender first, before going that route of course.

VW Beetles of the 1950’s and early 60’s, I don’t think they even had a gas gauge. Instead they had some kind of reserve tank, so when the main tank went dry, you could switch to the reserve to get you another 50 miles or so. I think that’s how that worked. If you didn’t want to fix whatever’s broken, maybe there’s some backup scheme like that for your car?

“VW Beetles of the 1950’s and early 60’s, I don’t think they even had a gas gauge. Instead they had some kind of reserve tank, so when the main tank went dry, you could switch to the reserve to get you another 50 miles or so. I think that’s how that worked.”

@GeorgeSanJose

Correct. It’s all done with just a simple valve…

I worked at a Volkswagen dealer back when we still stocked and sold those reserve tank valves. I think I still have one around here someplace… I used one on a dune buggy I built.

Two fuel supply (outlet) pipes stick up into the tank from the bottom, one is shorter than the other. When the reserve valve is “on” in normal run position the gas is drawn from the taller pipe. When you “run out of gas” then switching the valve to “reserve” draws gas from the shorter pipe, near the tank bottom.

One had to remember to switch from “reserve” after getting gas or there would be no reserve.

Most motorcycles I’ve owned have used a similar set-up. However, one motorcycle had a hump in the bottom of the “saddle tank” where it was formed over a top frame bar. When you “ran out of gas” (fuel feed was on only one side), you’d tip the bike over on an angle to spill some gas to the feed side of the tank and head for a gas station.
CSA

My bike had the hump in the middle but 2 petcocks, run out of fuel on one side, then open the other side for the emergency reserve. Would a petcock be a rooster that is a family friend living with you?