Electrical malfunctioning and starting issues.

If your fuel gauge is not working, there are several potential reasons for this issue:
1. Faulty Fuel Sending Unit:
-The fuel sending unit is a component in the fuel tank that measures the amount of fuel and sends signals to the gauge.
2. Faulty Gauge or Instrument Cluster:
- The gauge itself or the entire instrument cluster may be malfunctional. Electrical issues, such as a blown fuse, could also be a factor.
3. Wiring Issues:
-Broken or damages wiring between the fuel sending unit, gauge, and instrument cluster can disrupt the communication and cause the gauge to malfunction.
4. Bad Ground Connection:
-A poor ground connection can lead to inaccurate readings on the fuel gauge. Check for loose or corroded ground connections.
5. Fuse Problem:
-A blown fuse in the vehicle's fuse box could disrupt the electrical circuit that powers the fuel gauge. Consult the vehicle's manual to locate and check the fuse related to fuel system.

Without testing we'd only be guessing . Hooking up a factory or a professional type scanner , an checking engine sensor data parameters , checking fuel pressure an flow , basic electrical system testing - battery condition , charging system output testing etc.... GM did have instrument cluster problems , late 90's - mid 2000's . Stepper motor's inside the cluster that drive the gauge needles , an silver migration . Can cause all kind of electrical issues , battery draining over night , starting problems ,warning lights coming on etc....
How to repair GM Instrument Cluster Speedometer Gauge Stepper

Your best bet , take your vehicle to a qualified repair shop.

sounds electrical from here.

Sounds like your coolant level might be low. At highway speed you probably have enough coolant and with the air passing thru the radiator keeps the temp down, but at idle not so much. Or depending whether you have a belt drive or electric fan. Belt driven, could need a new belt.

check the vacuum lines for leaks first,since the cruise uses vacuum to pull on the gas pedal, and ac controls use vacuum to work the baffle doors in the ductwork..then start looking for loose connections on these 3 itemsrepost findings

Hi Nadhem, I believe you have an electrical short circuit somewhere along the lines. Check them out and look for anything touching the body where the insulation has rubbed through. Regards John

Most likely is the ecu. the question is it an ECU fault or one of its sensors have it diagnosed at a dealer

The first thing I would check is to make sure battery is securely tied down, cables are connected, and in good shape. Sounds basic but it has caused this problem for many of us.
- mark -

Sounds like an electrical issue Edwin, I would be taking it to the dealership and asking if there are any recalls before you spend any money. This doesn't sound like a mechanical problem or an issue that should be occuring, if it were your ECU or EPM I would probably say it wouldn't start after it shuts off.

Sound like the computer, is bad sorry to say.