'96 850 T fuel gauge

ernie143 · Post by **ernie143** » 20 Feb 2017, 17:09

My fuel gauge doesn't register a full tank. The highest the needle will register is just above the "12" to approximately 15 gallons. Is there a fix for this? I went to a bone yard and got another sending unit, but no change. Any suggestions? TIA!

Post by **shaker_chi** » 21 Feb 2017, 12:15

Ernie,

I had the same issue with my 98 S70. Not sure how it's related, but I also had a large evap leak in my system and it was throwing a code. I had a shop do a smoke test for me for $50 and I had a leak in the evap line under the passenger side near the gas tank. I fixed the line and now my gas gauge works fine. I can't explain the science behind it, but an evap leak could be the issue. Good luck.

Post by **benpineapple** » 22 Feb 2017, 07:19

i'm not 100% certain, but i believe your car may have 2 fuel level sensors. on my 98 v70 it has one sensor on the in-tank fuel pump assembly which only registers the lower tank levels, and also (in a different location) has a fuel level sensor that registers the upper fuel tank levels. i'm not certain this is the exact setup on your 850, but it sounds similar.

here's whats happening: your upper-level sensor has shorted out, the contacts are fixed, it is only registering one signal. if it had failed entirely and no electricity was flowing through the sensor, the entire fuel gauge would stop working.

when i got sick of my fuel gauge being dead, i did some digging. found that my lower-sensor was not registering a signal. so i cut those wires on the outside of the tank, and connected them. this allowed the other sensor to work, and to register on the dash. when i replaced my fuel pump a month later, i fixed the sensor.
if i were you, i'd go at it with a multimeter and find the culprit before ordering parts or hitting a pick n pull.

Post by **rspi** » 23 Feb 2017, 06:22

Do you think that the tank is actually filling up? Some people are having problems with the car not taking a full tank.

ernie143 · Post by **ernie143** » 27 Feb 2017, 15:26

Shaker_chi,

Thanks for your input! I'll check into it!

Best Regards,

Ernie

shaker_chi wrote:Ernie,

I had the same issue with my 98 S70. Not sure how it's related, but I also had a large evap leak in my system and it was throwing a code. I had a shop do a smoke test for me for $50 and I had a leak in the evap line under the passenger side near the gas tank. I fixed the line and now my gas gauge works fine. I can't explain the science behind it, but an evap leak could be the issue. Good luck.

ernie143 · Post by **ernie143** » 27 Feb 2017, 15:27

rspi,

Tank is definitely filling up!

Thanks!

Ernie

rspi wrote:Do you think that the tank is actually filling up? Some people are having problems with the car not taking a full tank.

ernie143 · Post by **ernie143** » 27 Feb 2017, 15:29

Benpineapple,

I'll get in touch with the Volvo dealership nearby.

Thanks for your time and reply!

Ernie

benpineapple wrote:i'm not 100% certain, but i believe your car may have 2 fuel level sensors. on my 98 V70 it has one sensor on the in-tank fuel pump assembly which only registers the lower tank levels, and also (in a different location) has a fuel level sensor that registers the upper fuel tank levels. i'm not certain this is the exact setup on your 850, but it sounds similar.

here's whats happening: your upper-level sensor has shorted out, the contacts are fixed, it is only registering one signal. if it had failed entirely and no electricity was flowing through the sensor, the entire fuel gauge would stop working.

when i got sick of my fuel gauge being dead, i did some digging. found that my lower-sensor was not registering a signal. so i cut those wires on the outside of the tank, and connected them. this allowed the other sensor to work, and to register on the dash. when i replaced my fuel pump a month later, i fixed the sensor.
if i were you, i'd go at it with a multimeter and find the culprit before ordering parts or hitting a pick n pull.

Post by **misha** » 27 Feb 2017, 15:42

benpineapple wrote:i'm not 100% certain, but i believe your car may have 2 fuel level sensors.

There is only ONE fuel level sender on ALL of these cars.

Post by **benpineapple** » 28 Feb 2017, 09:12

misha wrote:There is only ONE fuel level sender on ALL of these cars.

Nope, there are indeed 2 sensors. Might just be on AWD models (emission code 4). See this thread: viewtopic.php?t=38924 there are DS and PS sensors. Presumably for accuracy in uneven conditions? Not sure why have dual units. But when one fails, only the other will read its range in the tank (DS reads lower levels, PS reads upper levels)

OP, that thread might be useful if this is indeed what's going on.

Post by **misha** » 28 Feb 2017, 09:20

Just on XC because of it's tank shape.