Intermittent long crank before starting

Tiny
EARTH-TRAVELER
  • MEMBER
  • 2005 JAGUAR XJ8
  • 4.2L
  • V8
  • 2WD
  • AUTOMATIC
  • 78,500 MILES
I have an intermittent problem starting my car. It only happens after it has been sitting for a while (generally overnight) and does not always happen consistently. When the issue does occur, the engine still cranks fine and almost starts (low rpm), sometimes to the point where the starter kicks out and you have to cycle the key again to crank further. Sometimes this is a few extra seconds of cranking before it fires and sometimes it is multiple tries for ten to twenty seconds before it starts. As soon as is does start, it runs perfectly and does not cause an issue again until it has at least sat for an extended period of time. The problem was occurring almost daily and then I took a six hour interstate road trip and had no issues for several days even after it sat for a day. Then the problem slowly started up again. I have tried cycling the key to see if it is low fuel pressure (am I right there's no schrader valve to check on the 2005?) And that appears to do nothing. I have run injector cleaner through, but also does not seem to solve it. I had heard/read/seen somewhere that leaking injectors would be more of an issue on a hot start but do not remember well enough where or how I came to that conclusion to trust it. It seems like if the pump was failing I would have some issue running wide open but it is smooth and powerful. I have had no codes whatsoever. I do have a BlueDriver code reader and fuel pressure is low fifties when running, drops to immediately to high forties when car is shut off and right back up to low fifties when started again. I do not believe this is at the rail, not sure where it is getting the reading from but I think my app says at the rail is not supported on this vehicle. It has been a little while since I checked that. I have not been overly motivated to find the issue since it has never left me stranded and it is hard to diagnose something intermittent. I am getting ready to sell this vehicle and wanted to resolve this issue before I did. What should my approach be? I do not mind doing work myself and would rather not pay a shop a bunch of money right before selling. Thanks!
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Wednesday, November 15th, 2017 AT 5:46 PM

11 Replies

Tiny
JACOBANDNICKOLAS
  • EXPERT
It does sound like a fuel pressure issue. And to the best of my knowledge, there is no schrader on the fuel rail. Fuel pressure has to be checked at the fuel filter.
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Wednesday, November 15th, 2017 AT 8:51 PM
Tiny
EARTH-TRAVELER
  • MEMBER
With the car running excellently once started, would it be your impression that the issue is the check valve in the pump that is allowing pressure to drop when sitting? Also, is it possible to add an inline pressure regulator, maybe around the fuel filter to eliminate that problem? I just was looking at pumps online and they re almost $500.00 and no one has one in stock that I could work on this this weekend. Do you know where the OBD2 is getting the fuel pressure reading from on this model? Also, do you know what the correct pressures are for me to test pressure at the filter? Thanks for your help!
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Thursday, November 16th, 2017 AT 6:52 AM
Tiny
STEVE W.
  • EXPERT
It sounds like the check valve in the pressure line is failing and letting the fuel pressure bleed off. You can buy an external valve that gets installed in the line to prevent fuel from draining back. I use them now and then for issues like this where the pump tests okay but will not retain pressure.

The pressure sensor is on the fuel rail.

Fuel pressure should be minimum 43.5psi at idle, to 55psi at full throttle on a non supercharged version, Same low number but 77psi high on a supercharged car.
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Thursday, November 16th, 2017 AT 8:31 AM
Tiny
JACOBANDNICKOLAS
  • EXPERT
That would be my guess at this point or you have leaky injectors.
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Thursday, November 16th, 2017 AT 4:55 PM
Tiny
EARTH-TRAVELER
  • MEMBER
Installed a check valve in the fuel line a couple nights ago. Next day a little hesitation before starting. This evening, I got home from work at 5:30 and had to leave for an appt at 6, cranked it for about 10 seconds twice in a row, no indication it was even attempting to fire, jumped out and took a different vehicle. Came back 4 hrs later, jumped in and it fired right up, no hesitation whatsoever. Does that sound like injectors still? First time I've ever had an issue on a warm start. I did only drive the car a couple of miles home from work though. Can I just replace the upper and lower orings to resolve or is there more I need to do? The orings are stupid expensive! Any one know of a cheap place to get them if that's what I need?
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Tuesday, November 28th, 2017 AT 7:49 PM
Tiny
STEVE W.
  • EXPERT
Have you tried a different pump relay? Your initial post doesn't mention it but an intermittent relay could cause the pump to run then not run on initial start.
Should be R6 in the front relay box.

That car also uses the same pump control system that Ford used on many other vehicles, it varies the pump output pressure by switching the pump on/off rapidly. If it was failing it may not get the "start up" signal or not respond to it.
I would try the relay first, it's cheap and easy.
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Wednesday, November 29th, 2017 AT 6:48 PM
Tiny
EARTH-TRAVELER
  • MEMBER
I haven't tried it but am willing to. I am trying to locate the part online but haven't had any luck. Do you know of a site that would have them? If I can't find one, I suppose I'll just get a set of refurb injectors and swap those.
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Sunday, December 3rd, 2017 AT 10:20 AM
Tiny
STEVE W.
  • EXPERT
The relay is a common one should have a part number right on it. Injectors wouldn't cause this issue. Each one is driven by a different control transistor so they would all have to fail at once to cause a no start, and they wouldn't repair themselves.
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Sunday, December 3rd, 2017 AT 10:55 AM
Tiny
EARTH-TRAVELER
  • MEMBER
Did try another fuel relay to no avail. Finally bit the bullet and took the car to the shop, they had it for roughly 4-6 weeks. Initially couldn't duplicate the problem, then I borrowed the car back for a couple of days and had it happen 4 times in that time period. Was able to very specifically tell them to drive it a decent distance (15-30min) and then park it, wait 10-20 min and come back and try to start it and then they could get it to do it every time. They aren't a jag dealer but subscribe to tech lines and a jag tech led them to TSB JTB00268 and reference number SSM61657. I can't see all the info but they're telling me that the computer needs to be reflashed and I need to take it to a jag dealer. My closest is 2 hrs away, is it possible I could pull the computer and send it somewhere? I'm going to try calling my local Ford dealer and see if they happen to have the specialized stuff needed since Jag was owned by Ford during this time. If you have more info that can help me, let me know, otherwise I'll post back when I hopefully have a final solution.
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Friday, April 13th, 2018 AT 8:38 PM
Tiny
EARTH-TRAVELER
  • MEMBER
Oh also they were able to definitively rule out any fuel pump or fuel supply related issues as well before getting to the TSB.
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Friday, April 13th, 2018 AT 8:40 PM
Tiny
STEVE W.
  • EXPERT
There is an update listed for those numbers, It boosts the fuel delivery when you use ethanol blended fuels to cover a lean condition after a hot soak start. That is the situation you describe so it should work. The Ford dealer may be able to handle it as it is a simple re-flash. Removing it isn't a real option because the vehicle also gets a couple other module updates with that one so it is needed.
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Saturday, April 14th, 2018 AT 5:07 PM

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