Fuel gauge woes

[radarwhiz]

Having fuel gauge problems. This is the car I just got last week. Previous owner said it would indicate full but down below about half it would get pretty flaky. Attached image is the part I swapped off my donor car who's gauge worked fine. Now gauge does nothing at all, warning light still works though. Is there more that should be swapped? Or maybe the problem is elsewhere? Any help is appreciated.

[Roldie]

could be the floater.. Im having the same problem with mine. it works when it wants to, but i havent gotten the chance to work on it.

[radarwhiz]

Ok. Just found out there is are two floats. So is the signal that's sent to the gauge some sort of combination of the two? And maybe I just swapped the wrong one?

[radarwhiz]

Along with a float on each side there is this (attached image) with some type of sensor in it. what is it and does it affect the fuel gauge?

[radarwhiz]

Still haven't quite figured out exactly how this circuit works but I swapped out the cluster from the donor and it seems to be working now. I'll see once I run some gas out if it will move how it should. Of course I had to swap odometers too. I like how each gauge is individually removeable, makes it pretty easy.

[icingdeath88]

The two floats: One is for the gauge and one is for the gas light to come on.

[radarwhiz]

Originally Posted by icingdeath88

The two floats: One is for the gauge and one is for the gas light to come on.

That's what I initially thought. But after a closer look and testing, it seems that the potentiometers of each float are wired in series which means they could not have separate functions.
Has my electronics tech experience failed me and I'm completely wrong?

[oab_au]

Originally Posted by radarwhiz

That's what I initially thought. But after a closer look and testing, it seems that the potentiometers of each float are wired in series which means they could not have separate functions.
Has my electronics tech experience failed me and I'm completely wrong?

No you are completely right. They are connected in series. The light is a separate temp sensitive diode.

Harvey.

[radarwhiz]

Originally Posted by oab_au

No you are completely right. They are connected in series. The light is a separate temp sensitive diode.

Harvey.

So is that what this is:

[ARED 97]

It's really not a gas gauge anyways,, it's a fuel awareness device that when working keeps you guessing!!!

[radarwhiz]

Originally Posted by ARED 97

It's really not a gas gauge anyways,, it's a fuel awareness device that when working keeps you guessing!!!

......

[subychris91]

The two floats are there because the subarus have saddle fuel tanks and it uses both sensor to determine fuel level and the sub sensor on the drivers side has a tube with a pickup so that the fuel is sucked to the passenger side of the tank otherwise much below half a tank it wouldn't be able to get fuel over to the pump. The little sensor is a fuel temp sensor. Be aware i had a mouse chew my fuel level sender wires under the body ontop of the fuel tank requiring fuel tank removal for repair, causing intermittent fuel gauge operation.

[torxxx]

my car has developed a fuel gauge issue also. Its always been about 4 gallons off on 1/4 tank on down, but not the gauge stops working when it wants to, and doesnt read accurately at all anymore. I'm wondering if its a bad connection somewhere, or if a parts been known to fail on these cars?

[subychris91]

you can always pull the fuel senders out and manually sweep the floats and check the resistance with a DVOM to see if you may have one of the two falling out below a 1/4 tank the resistance change should be linear to the movement of the floats. worth checking out anyways.

[RojoRocket]

Originally Posted by subychris91

you can always pull the fuel senders out and manually sweep the floats and check the resistance with a DVOM to see if you may have one of the two falling out below a 1/4 tank the resistance change should be linear to the movement of the floats. worth checking out anyways.

Good call. I pulled the senders from my wrecked '93 that liked to fall to empty and back under half a tank, and checked them in this fashion. One was flaky and I found that the potentiometer was making poor contact. I pulled it apart and used a small thin washer inside the case to correct the pressure. Checked out sweet after the fix.

Glenn