Do not be concerned if your engine sometimes knocks lightly. However, if
it knocks heavily under most driving conditions while you are using fuel
with the recommended octane rating, see your authorized dealer to
prevent any engine damage.
Fuel quality
If you are experiencing starting, rough idle or hesitation driveability
problems, try a different brand of unleaded gasoline. “Premium” unleaded
gasoline is not recommended for vehicles designed to use “Regular”
unleaded gasoline because it may cause these problems to become more
pronounced. If the problems persist, see your authorized dealer.
Do not add aftermarket fuel additive products to your fuel tank. It should
not be necessary to add any aftermarket products to your fuel tank if you
continue to use high quality fuel of the recommended octane rating. These
products have not been approved for your engine and could cause damage
to the fuel system. Repairs to correct the effects of using an aftermarket
product in your fuel may not be covered by your warranty.
Many of the world’s automakers approved the World-wide Fuel Charter
that recommends gasoline specifications to provide improved
performance and emission control system protection for your vehicle.
Gasolines that meet the World-wide Fuel Charter should be used when
available. Ask your fuel supplier about gasolines that meet the
World-wide Fuel Charter.
Cleaner air
Ford endorses the use of reformulated “cleaner-burning” gasolines to
improve air quality, per the recommendations in the
Choosing the Right
Fuel section
.
Running out of fuel
Avoid running out of fuel because this situation may have an adverse
effect on powertrain components.
If you have run out of fuel:
•
You may need to cycle the ignition from OFF to ON several times after
refueling to allow the fuel system to pump the fuel from the tank to
the engine. On restarting, cranking time will take a few seconds longer
than normal.
•
Normally, adding one gallon of fuel is enough to restart the engine. If
the vehicle is out of fuel and on a steep grade, more than one gallon
may be required.
2007 Navigator
(nav)
Owners Guide (post-2002-fmt)
USA
(fus)
Maintenance and Specifications
285
