Why is the fuel sensor in my 300CD so quirky? When I just replaced it half a year ago it worked fine, now it will go up and down. It shows empty and the warning light is on an hour later it shows 1/4 full still with the warning light on and then it will shows empty with out much driving. When I fill it with 5 gallons the gauge shows 1/2 full, that means that there was still 6 or 7 gallons left, tank holds 21 gallons.....

Are they just unreliable or could there be something wrong in the wiring?

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1979 Black on Black, 300CD (sold), 1990 Black 300SE, Silver 1989 Volvo 780, 1988 300CE (vanished by the hands of a girlfriend), 1992 300CE (Rescue).

The hole which baffles the quick change of fuel level sensing is pretty small...
I suggest that very little algae could cause this to be quirky...
Perhaps if you take it out and clean it .....
I did this with mine when I flushed the tank.. and it is a much different animal now... don't know how permanent a fix it was... but pulling it out is pretty easy on the 123 models...( from inside the car)...

My fuel gauge appears to have the same degree of error that Jorn is concerned about. I tend to still have about 8 gallons of fuel left when the gauge is showing a 1/4 left. I always refuel at the 1/4 mark since I don't know how much it falls after that. I do keep tabs on the fuel economy so I have a rough guesstimate about my range.
I'm wondering if everyone has similar amounts of inaccuracy?

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DJ


84 300D Turbodiesel 190K with 4 speed manual sold in 03/2012

The sensor works fine till it shows 1/4 full on the gauge then it becomes unreliable. I will see if it's clogged by algae/dirt, there was some algae in the pre-filter the last time I replaced it.

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1979 Black on Black, 300CD (sold), 1990 Black 300SE, Silver 1989 Volvo 780, 1988 300CE (vanished by the hands of a girlfriend), 1992 300CE (Rescue).

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mine is just like that. it gets to about 1/4 tank and its not accurate. i ordered a new gasket so i can take out the unit and clean it. hopefully it will work again

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have no worries.....President Obama swears "If you like your gun, you can keep it

Check, clean or replace the Fuel Sender Unit. This should hopefully correct the problem. By replacing mine, I get a fairly accurate reading.

My fill-up is approximately 65-70 liters each time and about 650-700 kilometers or roughly about 9.8 liters per 100 km. mostly city driving.