How do you know when it is time to change a fuel filter on a 2004 lincoln navigator?

Ford scheduled maintenance schedule will tell you. You can find them online. I think ford.com has one somewhere in there. It is for all their vehicles. Any exceptions will be listed on the chart.How do you know when it is time to change a fuel filter on a 2004 lincoln navigator?at 40,000 miles at least, poss sooner. check the maint. section in your manualHow do you know when it is time to change a fuel filter on a 2004 lincoln navigator?i change mine when they clog...iv changed 1 in 40 yearsHow do you know when it is time to change a fuel filter on a 2004 lincoln navigator?40000miles depending on how hard you drive also when your gas mileage dropsHow do you know when it is time to change a fuel filter on a 2004 lincoln navigator?approx. 40,000 - 50,000 depending on the quality of gas you use and how its driven. Check your manual.How do you know when it is time to change a fuel filter on a 2004 lincoln navigator?30,000 miles or call ur lincoln dealer