I have a '99 F150 4.6 w/118,000. Occassionally starts hard, either hot or cold. Did fuel pressure test, pump is with-in manual specs. When I disconn. vac. to regulator pressure increases as per manual and decreases when I hook vac. back up, so I am assuming regulator is good. Only problem I find is that fuel pressure is not holding for up to 5 minutes as per manual specs after you shut it off. It drops almost instantly when I shut the engine off. I figured I'd replace the fuel pressure regulator as that was the easiest place to start. NOT. First of all instead of being what I thought would be a 15 to 20 dollar item, it is $60 plus. Secondly, there is no hex fitting to put a wrench on to remove it. After looking up replacement parts I see that some of them are press-in. Does tht mean I need another damn Ford special tool to replace this thing? Anybody had any experience with replacing one of these things? HELP. Thanx

 

Good question It does seem to be pressed in on my 01. I was going to ask this same question and came across your post so as soon as i figure it out ill let you know.

 

Pressed in ? Mine ( 98 5.4L ) comes off with a little persuasion. It's double o-ringed.

You might want to clean the MAF and re-boot first and check your vac harness. I don't know about the leak-down test really effecting anything IMO. As long as the pressure and regulator pass.

Clean the IAC as-well and make sure your up on maintenance, -like the filters.

 

You may want to check the fuel pressure regulator by clamping off the rubber fuel return line to determine if the fuel pressure continues to immediately drops off when you shut off the vehicle. If not, the regulator is good. The problem could be the check valve on the fuel pump.

 

the regulator is not your problem, it does not keep fuel pressure from bleeding down....

you most likely have a bad check valve in the fuel pump assembly or a leaking fuel injector, but if the truck runs fine otherwise its more likely the pump.