can't seem to fill the gas tank.......

[janko]

item in question is a 92 ford ranger. 4 cyl, manual tranny. anywho for the past couple of weeks when i go to fill the tank i can only get 3 or 4 gallons in. even with say 150 miles on the odometer. try with patience to top the thing off to no avail. have a factory shop manual and can find nothing relevant. stopped by the dealer. and no help here either. your suggestions will be greatly appreciated.

p.s. tried sites tied to 'ranger enthusiasts' with no success.