Hope you can help. We have an older buick la sabre, with 230k
well cared for, (wife) and as of late, it does ''this''.  When the gas
tank has about 3gals in it, the car will act as if it is out of gas.
We were shopping, and it ran out of gas, and after getting a push to a
station, on a whim I tied to start it, fired right up.  It was trouble
free until yesterday  (couple of months went by) and the car had about
6 gals in the tank, but it was 'acting empty', sluggish on inclines,
but it would 'settle out' when no hills.  After the wife filled the
tank full, it runs find. I went for a spin, it pulled fine, even on a
'good hill' near here.  
   I "think" it is the fuel pump, (should be the car is old enough) I
bought the car from my brother and I know he did not have to replace
the fuel pump, and we haven't, so that is alot of miles on one pump.I
would just like your ''input'' so when I talk to the mechanic, I don't
sound too stupid.   Thanks in advance. cl.