Hey guys,
00' F150 4.6 152,000 miles. Have had this problem since I got the truck at 60,000 and heard different opinions on what it is. Just want to see what yall think and if it is an easy fix. If I try to start the truck after sitting for between 20 min and about an hour and a half, it really struggles to start. Sometimes takes a couple turns of the key. However, if it is right after you turn it off or after it has sat for a while, starts right up. Had to replace starter about a year ago, probably wore out because of this issue. Anyway, main thing I have heard is about some sort of fuel primer issue. Any ideas on what it is and what I would be looking at to fix it? Thanks

 

Sorry I can't offer any help but I'm tagging your thread and bumping it to the top because I also have a 2000 4.6 that does the same thing.

 

Good to know I have some company

 

Did a search and found this:

"After a 1-4 hour engine soak time, long crank times and/or long crank to start followed by a stall may occur on some vehicles. No further stalling or rough idle will occur after the engine is running. The long crank and/or stall may be due to the Idle Air Control (IAC) Valve sticking. "

 

I replaced that about 2 years ago for seperate issue. So that is ruled out, in my case anyway

 

I had a very similar issue, although mine was also accompanied by other symptoms....however it may be applicable.

My gas pressure regulator went bad. What that meant was that it would 'dump' fuel off the gas rails while driving giving me a ‘miss’.

However, there was a secondary symptom that I wrote off as being "normal for an old truck" and it was just as you described. If I started the truck soon after turning it off, it started right up. If it sat for hours, particularly overnight, it would take a whole lot of cranking to start. I just figured it was 'cold natured'. Well, come to find out my gas pressure regulator was bleeding/relieving the gas from the fuel rails, and therefore when I went to start the truck, I had to wait until my fuel pump repressured the rails before she had enough gas to start.

Anyway, a gas pressure gauge on the fuel rail verified the problem. You could watch the pressure drop as she sat over night. I put on a new gas pressure regulator, and walla!, my 1999 F-250 starts like she's brand spankin' new.

Stone

 

Thanks for the info Stone. Where is that on the engine? How much does it cost, and was it a hard install? Thanks

 

Well, I'm not very familiar with the 4.6L in the F-150, but quessing that they are similar, here goes....

Mine was on the driver side fuel rail, about midway down the rail. It looks like a small UFO with a vacuum connection on the top of it. Here's a link to NAPA with what may or may NOT be your part.

NAPAONLINE®

It was ~$60 for me and it was about a 10 minute install. A Haynes manual should walk you through it, but it was as simple as two small screws and a vacuum connection. Some are clamp on. If my NAPA guess was right, it looks like yours is a clamp on. So you just unclamp it, replace, reclamp.

This is just my guess. You can buy a gas pressure gauge at most auto parts stores to verify that this is your issue. The pressure nipple is usually on the passenger side fuel rail. The Haynes manual should tell you what pressure to look for. My was supposed to be ~45psi I think, and it would fall off to zero over night.

I'm sorry I can't be of much more help than that, I just don't have access to a manual for your truck/engine.

If this is your issue, your truck may come alive once you fix it. My truck did. I guess the miss and the loss of power was just so small and subtle that I never noticed it until after it was fixed.

Stone

 

I might have a different problem. My truck starts easily when overnight cold, it just requires extended cranking after sitting hot for 20-30 minutes. The truck is new to me so I don't have any history to go by.
You could probably test for a regulator issue by letting the key sit in the 'run' position for a moment before trying to start. If it starts readily after allowing the fuel pump to pressurize the rail.................

tchernosky,
Does your truck start quickly when cold?

 

To check the regulator, pull the vacuum line and see if gas comes out. If so, the diaphragm is ruptured.

I would also check the fuel pressure when it won't start.

 

right away when cold, yes!

 

thanks for all that info by the way Stone, appreciate it.

 

Oh, np.

I just had to throw it out there, just in case that was your issue. Took me months to figure it out.....

Anyway, be sure to report back what you find so that we can all learn from it.

Good luck!!!

Stone

 

Oh, and one thing, my regulator was bad, but there wasn't any fuel in the vacuum line as LxMan is describing. It was bleeding fuel back into the tank. The diaphram wasn't ruptured, it was just holding the pressure set point like it should. The gas isn't relieved into the vacuum system, it is relieved into the gas tank.

LxMan are you talking about a total failure of the diaphram between the vacuum side and the gas side? Mine was much more subtle that than. It was just releiving off the pressure on it's own.

Stone

 

Yes, failed diaphragm with gas in the vacuum line. I have never seen one that failed any other way. Usually a check valve in the pump fails that causes total fuel bleedoff.