When the 2001 Isuzu Rodeo stops and idles for more than a few minutes the gas gauge needle reads empty. When I start driving again the gas gauge needle goes back to the actual reading. My practice is to fill the tank when is goes to one-half full; because the gas gauge is not reliable. Thank you for taking the time to read the question and give me some feedback from your "Words of Wisdom" on what could be the problem.
Likely bad fuel level sending unit, it's a known issue with 2001 Isuzu Rodeo's.
One of my friends had a 90’s Jetta where the gauge would fluctuate every time you accelerated or decelerated. Technically it is actually an “accurate” reading since the fuel always sloshes around. But too “accurate” to be useful.
What you are doing is a band aid is good. You could also use the mileage gauge to guesstimate how far you can go on a tank.
It’s probably a bad sensor. But also not worth it to fix it.
