Inaccurate Fuel Gauge readings

[GSV]

My 98 Nissan Frontier's gas gauge has never worked properly since I bought it used. It always reads about 1/4 of a tank below its true fill level.

Now my wife's 99 Subaru Legacy is doing the same thing.

I can live with using the trip odometer to calculate remaining fuel level but if this can be fixed without pulling the fuel tanks out I'd like to try.

Do modern cars still use a float inside the tank or is there a sensor that craps out and can be replaced?

thanks!

 

[SteveD2]

No, I'm pretty sure they all use a float, which would mean taking out the tank. I like to fill up right when the gauge is at one of the 1/4 marks, that way I know how many gallons are actually left at that mark in the future...

 

[Brent]

GSV,

Go to a Nissan dealer and ask them for a copy of service bulletin NTB99-064.

This bulletin describes your complaint. The procedure is to first clean the ground connections under each the passenger and driver side kick panels. Remove the paint around the hole in the metal to obtain a good connection. Be careful when putting back the screws because they strip easily.

If that doesn't work, the next step is to replace the sendor in the tank.

If the problem still exists the actual instrument panel may need to be replaced.

I cleaned my grounds and the problem didn't go away. The dealer then replaced the fuel sendor under warranty and it mostly corrected the problem. The guage is still off a little, but nothing like it was.

Warranty would only apply under 36/36.

I hope this helps.

Brent

 

[Brent]

If you have to replace the fuel sender it is easier to remove the bed. The job can be done this way without draining the fuel and taking down the tank.

Brent

 

[GSV]

Thanks for the tips.

The Subaru has a seperate fuel level sending unit that can be easily removed and cleaned. (I've been doing some research) The $tealers usually just replace them but cleaning the variable resistor and contacts seems to work for some so I'll try this first on the Soob.

Brent, thanks for the info on the Nissan. I'll try cleaning the contacts this weekend. What is weird is 1 out of 5 fillups will pop the gauge up to Full.

 

[9c1]

I don't recall all the details, but one manufacturer (I think GM) put out a bulletin about inaccurate fuel level indicators (I hesitate to call what is in modern cars gauges). Seems a chemical in the gas was corroding the contacts in the tank level mechanism. Cleaning the contacts was the indicated solution. Might be the same situation here?
Terry

 

[GSV]

I started another thread in the additive section. 3M 8813 fuel system cleaner

The surprising thing about this cleaner is it seems to have cured the Subaru's fuel gauge inaccuracy.

I'm using it now in my Nissan and so far so good. The gauge is still tracking towards E and I'm just a little past 300 miles. It usually dives down below E after 270 miles. I'll watch it for a few tanks before I declare this problem solved but if this really works it beats pulling parts out of the fuel tank any day.

 

[kansaisubaru]

I've had fuel level inaccuracy problems with my Subaru Impreza. The cure: Chevron Techron or other fuel system/injector cleaners. The problem went away and has yet to come back. This worked on a Chevy Corsica too with the same problem.

 

[Ethan]

GSV,

Any updates on this?

Ethan

 

[GSV]

6 MONTH UPDATE

Well the 3M stuff did help for a while but it is not a long term cure. Both vehicles mentioned are starting to go back to their old ways after 6 months. They are still better than they used to be but slipping.

I suppose treating the tank with this stuff 3 times a year would work but I don't know if this would be advisable.

 

[ChrisW]

what brand fuel are you using? i here sulfur levels in fuel can do this, esp in Audi/VW cases. Shell had some bad gas a while back.