The last 2 times I have filled up my 2006 Isuzu Ascender the gas gauge goes nuts! first it won't register that the tank is full (although I just pumped 18+ gallons of gas!). the low fuel light is on, and then the check engine light comes on. slowly the gauge tries to read, which usually takes a few days of the gas gauge just bouncing all over the place. Then the check engine light goes off. And, within a few days, its reading properly again.
The first time it happened I thought perhaps i just bought "bad gas." It happens. But, when I filed up the next time at a higher end gas station, the problem happened again!
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Re: Fuel Gauge reads empty, but tank IS full
Fuel sending Unit Is Faulty. This In A Float That is Useing this Foating Mechanics Turning it into An Electrical Signal that you See Incar as A Reading. its Somewhat Costly as The Fuel Tank Must Be Removed. _-_- Rarely The Wiring or Gage is the Problem But Worth Ruleing Out , An Honest Mech/Tech will Find Witch One it is So Sorry BUT Good Luck With that Unless You Know One Personaly. I Hope this Helps You Find the Problem As Its Only 1 of 3 Items
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the tank sending unit works off a resistor to read the amount of fuel in the tank. you will need to replace the entire tank sending unit for fix this problem. As for the door problem....The short in the wiring for the door has to be found to repair
There is a small float in your gas tank something like the one in your toilet tank(no I'm not kidding).Its position regulates an electrical current and based on its resistance gives a reading on your gas gauge. My best guess is this float got a bit stuck in the low position and it shock free after some time on the road.This is more common than you would think.Keep an eye on it and if it freezes in empty position or sometimes full position it will need to be replaced. Hope this helps,good luck.
Some of these GM's have a seperate fuel guage relay under the dash. Their not cheap. Since you could have anything from a bad sender in the tank to a bad relay its best to leave this to a professional. Next time this happens try smacking the fuel tank a few times hard. If the gauge goes up its most likely a sender in the tank issue. If nothing happens then it really needs to be diagnosed correctly.
This is a normal concern.
The instrument cluster uses 4 different operating modes to calculate the fuel level:
Anti-slosh (default mode) Key OFF fueling Key ON fueling Recovery After a fuel fill up, the time for the fuel gauge to move from empty (E) to full (F) ranges from 2 seconds to 55 minutes depending on which operating mode the fuel gauge is in.
The default fuel gauge mode is called the anti-slosh mode. To prevent fuel gauge changes from fuel slosh (gauge instability due to changes in fuel sender readings caused by fuel moving around in the tank), the fuel gauge takes approximately 55 minutes to go from empty (E) to full (F).
The key OFF fueling mode (2 seconds to read empty [E] to full [F]) requires 3 conditions be met:
The key must be in the OFF position throughout the entire refueling of the vehicle. At least 15% of the vehicle's fuel capacity must be added to the fuel tank. The instrument cluster must receive a valid key ON fuel sender reading within 1 second of the key being put into the RUN position. The key ON sample readings are considered valid if the fuel sender reading is between 15 ohms ± 2 ohms and 160 ohms ± 4 ohms. If these conditions are not met, the fuel gauge stays in the anti-slosh mode, which results in a slow to read full (F) event.
The key ON fueling mode (approximately 90 seconds to read empty [E] to full [F]) requires 3 conditions be met:
The transmission is in PARK (P). The key is in the RUN position. At least 15% of the vehicle's fuel capacity must be added to the fuel tank. In key ON fueling mode, a 30-second timer activates after the transmission is put into the PARK (P) position (automatic transmissions). When the 30-second time has elapsed and at least 15% of the vehicle's fuel capacity has been added, the fuel gauge response time is 90 seconds to read from empty (E) to full (F). When the transmission is shifted out of PARK (P), the fuel gauge strategy reverts to the anti-slosh mode. The key on refueling mode prevents slow to read full events from happening if the customer refuels the vehicle with the key in the RUN position.
Recovery mode is incorporated into the instrument cluster strategy to recover from a missing fuel level input during a refueling event. Missing fuel level inputs result from intermittent opens in the fuel sender or its circuits. Recovery mode (empty [E] to full [F] approximately 20 minutes) is initiated when the following 2 conditions are met:
The instrument cluster is in the anti-slosh (default) mode. The actual fuel level in the tank is greater than what is being displayed by the fuel gauge