In most cases, the fuel sender is just dirty and needs a gentle cleaning to allow the float to float. Just pull it out of the tank, let it dry, and then turn it upside down and back a few times, slowly, to determine where it sticks.

You can clean it with gasoline or a throttle body cleaner. Just be very gentle with it. See the 700/900 FAQs.

Klaus
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I still miss my 164 and my 854T. Just driving a V70R :)

you should get at least 400 miles highway probably closer to 440 depending on how well the car is tuned, our fuel guage is also on the fritz and we refill at 350 miles

This of course depends on what MPG you are getting. If it is all city stop and go driving it could be as low as 18 mpg, but my 93 turbo wagon has gotten as high as 35 mpg on the highway with a tailwind (converted to M46 transmission and 3.31 axle). Based on this range you could go anywhere from 324 miles @ 18mpg (assuming you can use 18 gallons of the 19.8 capacity - margin for error) to 630 miles @ 35 mpg. Filling up every 300 miles should be safe if the car is in good tune (normal fuel consumption).

The fuel sender which tells the gauge how much gas is left can go bad in these cars but they are usually repairable. On my car the float which slides along two resistors making electrical contact between them became too loose - electrical contact was intermittent and the gauge was erratic (usually read too low). I was able to fix it for free simply bending the contact until it made better contact while still allowing the float to move. Took some trial and error. There are instructions in the 700/900 faq.

Eric