02 Impreza Fuel Gauge Inaccurate Reading

[Daskuppler]

Hello Everyone,

 

I have a 2002 Impreza TS with approximately 140k in it. For several years now, the fuel gauge has been inaccurate.  The gauge shows full and slowly works down as I drive. The low fuel light eventually comes in, but when I fill up, it usually takes around 10 gallons, sometimes it will take 12.

I saw a post on NASIOC saying they had used really fine sand paper to sand off corrosion on a couple resistors on the fuel pump assembly, does anyone know if that is the fix for this? Is something else going on?

No codes, no driveability issues, and fuel economy is as expected for driving conditions. This is more of a nuisance than anything

 

Cheers

[lmdew]

There are two sensors/resistors one on each side of the tank due to the driveshaft hump.  

The resistors can become iffy.  There is Fuel Sensor cleaner you can add to the tank.

If you pull the sensors out, make sure you do not snap the 8mm studs on the tank.  If the car has rust issues, I'd just leave it as is.

[Daskuppler]

2 hours ago, lmdew said:

There are two sensors/resistors one on each side of the tank due to the driveshaft hump.  

The resistors can become iffy.  There is Fuel Sensor cleaner you can add to the tank.

If you pull the sensors out, make sure you do not snap the 8mm studs on the tank.  If the car has rust issues, I'd just leave it as is.

I've used some cleaners in the past and it's not changed anything. Maybe I'll try again and let it sit for a while and ride the motorcycle. There's not much rust, but I do live in a snow state so there's likely more than I'm aware of

[lmdew]

Pull the access covers and soak the studs with PB Blaster.  That way they will be ready to go when you want to pull them.

Fill the tank and go by mileage!

[heartless]

1 hour ago, lmdew said:

Fill the tank and go by mileage!

This, right here, 100%
Reset the trip odometer at every fill up, and go by mileage. I have not trusted a fuel gauge (on ANY vehicle) in many, many years.

if the light actually works like it should - and yes, they are supposed to come on early enough that you can get somewhere to get more - you can use that as a good indicator of how many miles you can safely get out of a fill up

generally speaking, out of a 10 gal fill, i would expect between 275 to 300 miles, depending on specific vehicle, conditions and area driven..
my '04 Forester gets around 280-285-ish out of 10gals, on typical midwestern rolling terrain two lane roads - very little freeway driving.