Spiders and dirt daubers love to set up shop in the burner tube. If it’s blocked the flame can be real sooty or fail to light. Use compressed air or a brush to clean it out. If it has an auto igniter you should be able to see and hear the spark. More info would help (age, brand, model).
2013 F-350 CC SB 2WD 6.7PS
2013 Eagle Premier 351 RLTS
-SOLD- 2012 X23B
-SOLD- 2003 Ford Expedition 5.4, Bilstein shocks