FORD 1999 Ranger - Manual (Page 180)

Fuel Filler Cap
Your fuel tank filler cap has an indexed design with a one-eighth turn
on/off feature.
When fueling your vehicle:
1. Turn the engine off.
2. Carefully turn the filler cap counterclockwise 1/8 of a turn until it
stops.
3. Pull to remove the cap from the fuel filler pipe.
4. To install the cap, align the tabs on the cap with the notches on the
filler pipe.
5. Turn the filler cap clockwise 1/8 of a turn until it stops.
If the “Service Engine Soon/Check Engine “ indicator comes on and stays
on when you start the engine, the fuel filler cap may not be properly
installed. Turn off the engine, remove the fuel filler cap and reinstall it
being careful to align the cap properly.
If you must replace the fuel filler cap, replace it with a genuine
Ford or Motorcraft part. The customer warranty may be void for
any damage to the fuel tank or fuel system if a genuine Ford or
Motorcraft fuel filler cap is not used.
The fuel system may be under pressure. If the fuel filler cap is
venting vapor or if you hear a hissing sound, wait until it stops
before completely removing the fuel filler cap. Otherwise, fuel may
spray out and injure you or others.
If you do not use the proper fuel filler cap, the pressure in the
fuel tank can damage the fuel system or cause it to work
improperly in a collision.
Choosing the right fuel
Use only UNLEADED FUEL for non-flexible fuel vehicles. The use of
leaded fuel is prohibited by law and could damage your vehicle.
If your vehicle is a flexible fuel vehicle (FFV), use only UNLEADED
FUEL and ETHANOL (E85). The use of leaded fuel is prohibited by law
and could damage your vehicle.
Maintenance and care
180