I HATE this fuel gauge!!!

[aschulz261]

Ok...this tank is highly abnormal and I never expected it to have even what could be considered to be "good" mileage.

 

The car has been parked for almost 4 months due to an extended trip I was on. Before I left, I filled the tank to make sure there was no chance of collecting water in the tank. I got back and, as expected, it wouldn't start. It came close....it unlocked the doors, but I think it gave it's last gasp when all the computers turned on because it wouldn't start. No problem. Hooked a charger to it and let it run all night and it was fully charged by morning.

 

I've been driving it a lot to try and get this gas used up since it is fairly old. Yesterday, it was about time to fill it up again. And here begins my frustration.

 

The fuel gauge turned yellow and got the LOW FUEL message. DTE was 38 miles.

 

I drove it 11 miles back to town to fill it up. That trip averaged 68.7 mpg! YAY!

 

I got to the gas station with DTE showing 7 miles (not even going to try and figure out THAT math)....and.....the fuel gauge was WHITE again. WTF! 7 miles DTE and not even a YELLOW gauge?

 

SOOOO, I fill it up and it takes 11.56 gallons! WTF?

 

Car computer showed 28.7 mpg for that tank. Hand calculations show 26.1 mpg

 

so, in the end, DTE shows it as empty. Gauge shows adequate fuel. Actual level...almost empty.

 

Why can't it just tell you how much gas is really in the damn tank?

[GrySql]

Dead batteries can cause computer malfunctions.

My guess is that the car's PCM is trying to re-learn the condition of the cars systems.

 

There have been many posts here about this subject.

[murphy]

DTE is a "guess" based on how the car has been driven. Even if the car knew exactly how much gas was in the tank it has no way to know how you are going to use that gas. You could drive to the top of Pike's Peak (over 14,000 feet) and get horrible gas mileage. Or you could already be at the top of Pike's Peak and get fantastic gas mileage driving down. Those are extremes but illustrate the point that all the car knows is the average use in the past and will use that to calculate the DTE.

 

If your 12 volt battery went completely dead it may have been damaged. It's a "starter" battery and their construction does not take kindly to being fully discharged. The owner's Manual says to disconnect the 12 volt battery if it is going to sit longer than 30 days.

[lolder]

The 12 vdc battery is not used for "starting" in the regular sense of turning a starter motor but it does have to be in good shape. Completely discharging any battery may be bad for it. Yours had some life so it wasn't completely flat. You can't leave modern cars particularly hybrids that long without charging the 12 vdc's.

The algorithm that calculates the DTE is probably starting over. It generally tries to arrive at zero with about a gallon of gas remaining.

It sounds like the only discrepancy was the color turning white again. That was probably triggered by the 68.7 mpg trip. It will probably sort itself out. Disconnect the 12 vdc next time or arrange to have it charged as per the manual.

[Easy Rider]

Dead batteries can cause computer malfunctions.

 

And leaving the 12 V battery sit in a mostly discharged condition is not good for the battery.

If possible a battery "tender" should be used for long periods like that.

 

That also has been discussed on here quite a bit.