It's a 1999 5.4, and I have a long crank/rough start, only after sitting for 6+ hrs or so. I replaced the fuel pump about 6months ago, because the fuel pressure was weak, and I thought it would cure the long crank issue. It did not.
The new pump ran with the same general fuel pressures:32ish when running,jumps to 42ish, with no vaccum to fuel regulator, would hold it's pressure for a few hrs, but not overnight. So I moved on, troubleshootingwise.
Changed crank position sensor, cam position sensor, cause they were cheap and easy to swap. New IAC, fuel pressure regulator, same reasoning,cheap and easy, but no change. Cleaned TB, MAF and IAT cleaned with MAF Cleaner, and little EVR filter thingy. Battery Is a new Oddyessy, holds a charge at 12.6-12.7v. I replaced all the chassis ground straps, the battery cables, and harness, starter is a new PowerMaster Hi-Torque.I was gonna try the CHT sensor next, but it looks hard to get into. So after hours of looking on the net, I'm back to thinking it's a fuel issue. Could have gotten a crappy new pump,eh?
The pump will hold it's pressure for a few hours, but by next morning, it's down to like 10. The thing that gets me thinking it's something else, though, is that even if you cycle the key to build up fuel pressure, it still will hard start/long crank.

Anyone have anything like this happen before? What's your thoughts?

 

You may already know this, but the pump doesn't determine the fuel pressure; the regulator does. I don't know for certain (trying to recall my mustang days when I had a pressure gauge), but I don't think it matters, nor is it supposed to, hold that pressure for a certain/extended period of time. As long as fluid remains in the lines, the pressure would build up/return to normal pretty gosh darn fast once the pump starts running...basic physics.

 

Does it smell like gas after sitting? I put new injectors on mine and with it a few months the hard start acured and it would smell like gas 10min after I shut it off. I put my old injectors in and all is good now. also, I thought fuel pressure for the expy is ok any where between 32-38. I got mine at 38 and 43 with no vacuum. I have a adjustable regulator so I can control mine. I can tell a difference when mines around 35#'s so I keep mine in the high range.

 

Looks like I'm stuck again,then.Maybe spark? I replaced coils and plugs in June, Visteon and Motorcraft. What else could I look at? I thought CHT, but I used my Edge programmer to watch it today, and it seemed to respond correctly. It started around 50 and rose to 198. Ambient air temp today was around 45-50ish. The IAT temp was around 45-50 during the ride home from work, too, so they both seem to be working.

Nope, I can't smell fuel after sitting. I tried flooring it during starting, in case it was a leaky injector, but still the same long crank/hard start.

Bummer

 

I did not see any mention of replacing the fuel filter. Could be the simplest of things.

 

Sorry, forgot that one, It was replaced along with the fuel pump about 6 months ago, but did not help the problem.

 

Not sure what the leakdown rate is supposed to be on these trucks but I do know in my GMC van they say 10 minutes minimum and generally if you have a problem it leaks out in seconds

 

Seems like like it 30min - an hour.......

 

If the pressure drops to zero immediately, that's all but indicitave of a leak, in which case you should either smell it or find it somewhere.

 

If it holds for a few hours, that's not your problem.

 

Yeah, it will hold for 4+ hours, drops to 10psi by morning, 8 hours or so. Guess I'll keep searchin'

 

Found these http://www.ebay.com/itm/Fuel-Injectors-ULTIMATE-UPGRADE-1997-2003-Ford-F150-5-4L-V8-ASNU-4-Hole-BOSCH-/331044209365?vxp=mtr on ebay, and thought that for the price, I would swap my injectors out for these one. My stockers have 250k on them. Anyone have anything good or bad to say about them? I've pretty much swapped out everything that relates to starting the truck, so I got to be close.....

 

Dont expect it to run better. The injectors these trucks came with last usually the life of the truck. That said I've bought them like this on e-bay. Not sure if it was the same seller.

 

The reason I was looking at injectors was because I'm thinking a leaky or faulty injector. I relieved all the fuel pressure last night, and after priming it up this morning, it started better than usual, not perfectly, but way better. Any thoughts?

 

I might be way off base here, but I thought a stuck open EGR could produce the same issue.

It would be very cheap and easy to do a suck test on the EGR. I know that should throw a code if it's faulty, but worth looking at.