I have a 2000 F150, 4.6, 2WD that has become hard to start. The starter turns for about 5 seconds or more before starting. Fuel pressure is good and I replaced the IAC valve. Can anyone help?

 

What shape is the battery in? How about the starter and cables, are they clean and tight? A corroded battery cable will have higher resistance which will slow down the starter and make it harder for the engine to fire up.

 

As long as the engine is turning over fast enough, you may be in need of a complete tune, as the truck being 7 years old, and you didn't mention what the milage is. If approaching the 100k mark, the plugs, wires, O2 sensors, are all getting tired, and may be contributing to the slow to start situation. At least see if there is a stored code and go from there??

 

How did you check the fuel pressure? Did you do a KOEO and a KOER and what was the numbers? Another thing, did you leave the gauge hooked up for 20 mins after the engine was turned off to see how much the pressure drops? What I am trying to rule out is the fuel pressure regulator.

 

summer heat causes the engine to get hotter and the fuel in the fuel rails will vaporize and so when u initially crank all ur getting is a light fume of fuel not enough to turn the motor over. so u gotta crank it and give it throttle to open the injector and boost the fuel more to get it to start mine does it every year same time.

 

I tuned it up less then a year ago, have been thinking about the O2 sensors but can't see why those would cause a start problem. It cranks strong, and has been hard to start even before it warmed up here. The fuel pressure was in the 35psi range. didn't check after 30 min though. both KOEO and KOER were in range by the book