1996 850 GLT Wagon Gas Gauge Never Reads Full

NotAnElectronicsGuy · Post by **NotAnElectronicsGuy** » 05 Jun 2024, 19:56

I am not the best 'searcher', so I may have missed the answer... I have a 1996 850 GLT Wagon, 5 cylinder, 5 speed, 265,000 miles.

For the past year my Gas Gauge has not read Full. I even got to the point that I took bubble levels to the 3 statons I use, and checked my driveway, to maake sure I was on level pavement. Around the same time I started having "hesitant" starts, (hard to describe). I replaced the coil, spark plugs/wires, and last week I replaced the batter when it got to the questionable CCA level. City mileage is not great, (avg. 18 mpg), but it is responsive, and has plenty of power on the road.

When I fill up, the gauge reads about 1/4 below the 18 galon mark, sometimes just a but higher. On the opposite end, the fuel warning light seems to come on when there are about 5 to 6 gallons left.

Can someone tell me if I can adjust the float, or find another solution?

I am a fairly decent mechanic. I can cut, solder, and replace wires, and I do have a couple multimeters I can get by with, but I do not have the electronic equipment- nor the money to purchase them- to check engine codes, etc.

Any suggestions? And many thanks!

Post by **jonesg** » 06 Jun 2024, 06:38

whoever replaced the pump or opened ther\ tank failed to line up the pump properly.
the float should be lined up so the float is in line with the car front to rear.
if you open it up, be certain to disconnect the battery or you'll set the srs fault light, then you'll need a decent code reader to turn it off.

NotAnElectronicsGuy · Post by **NotAnElectronicsGuy** » 06 Jun 2024, 08:56

My fuel pump was replaced around 4.5~5 years ago, and the problem did not show until 3+ years later. I will take a look at that, but it does seem likely.

454cid · Post by **454cid** » 06 Jun 2024, 09:17

Assuming it works like most senders, it could have a broken resistor.

Looking on Rockauto, and FCP I'm not seeing what the sending unit looks like. Maybe it's built into the housing assembly? I can buy a separate part for my truck, but I'm not seeing a similar product for my 96 850.

If you've got hard starting, I'd check the fuel pressure.

RedBrickCollector · Post by **RedBrickCollector** » 06 Jun 2024, 10:11

I have the same issue and the local volvo specialist tells me it's usually corrosion on the part that the float sweeps for resistance. Haven't gotten around to it but putting that out there

NotAnElectronicsGuy · Post by **NotAnElectronicsGuy** » 06 Jun 2024, 12:09

Fuel pressure checked O.K., thanks.

RedBrickCollector: What do you mean by "sweeps", i.e.; "... the part that the float sweeps for resistance."?

Post by **Clemens** » 06 Jun 2024, 13:40

regarding the hesitant starts: does the motor turn freely or is it slowish? If the main power wires get corroded, the starter may not turn as fast as it should and can cause hesitant starts.

NotAnElectronicsGuy · Post by **NotAnElectronicsGuy** » 06 Jun 2024, 16:49

If it is not raining tomorrow, (starting to feel like I need webbed toes/fingers, and gills), I will pull the air filter box and see if the flapperbetween the hot air and cold air intake is FUBAR.
I replaced the Air Mass unit maybe 5 years back, and it seems like that is working O.K.

I will try anything and everything else before I tackle going into the gas tank... my bad back and knees have been there before on a 1988 wagon with a dead fuel pump.

Clemens, Starter cranks good, do good in fact that a couple weeks ago I left it ingear, and almost jumped a curb.
Starting is more like it "hesitates" [?] for a second or three, rather than it cranks and starts right up. That also seeemed to have begun a little over a year ago.

Post by **BEJinFbk** » 06 Jun 2024, 17:24

Just for grins, where is your voltage level
hanging out when the car is running.
I’ve never heard of low system voltage
causing that particular problem, but
it’s always a good thing to consider
with electrical problems.

RedBrickCollector · Post by **RedBrickCollector** » 07 Jun 2024, 10:35

NotAnElectronicsGuy wrote: ↑06 Jun 2024, 12:09 Fuel pressure checked O.K., thanks.

RedBrickCollector: What do you mean by "sweeps", i.e.; "... the part that the float sweeps for resistance."?

I haven't opened the 850 specifically but like mentioned above fuel senders work like potentiometers. One side is static and one side is connected to the float. The part that doesn't move gets swept by the float as it travels and that changes the resistance. Corossion/oxidation/dirt can build up and have it read higher than it should.