XK / XKR ( X150 ) 2006 - 2014

Engine Problem

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  #21  
Old 07-27-2017, 01:02 PM
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Originally Posted by amcdonal86
Yikes, this makes me wonder if I should replace my injectors preventively as I have about 70k miles on mine!

What about the rest of the engine.

Its no longer a good idea to replace things proactively in a car. The part you threw out may have lasted twice as long as the new made in mexico part. Or new 'green' manufacturing laws are forcing the German manufacturer to use biodegradable oils in the rubber.

Other than a timing chain, there is virtually no part on a car that you wont be better off to wait till it breaks- if it breaks. Because there is no downside other than inconvenience of towing.

If you know a part in a car to be weak, it pays to have a replacement on hand. If that part takes a long time to procure. You can pay twice as much for a part if you get it when they have you over a barrel. I paid a $1000 for a fuel pump on my truck because I was in remote pacific northwest. When I got to my destination and told my friend who has the same truck, he taught me that he carries a spare one. Only cause its a known issue.
 
  #22  
Old 07-27-2017, 02:28 PM
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So they all failed on one bank? That's really, really suspicious.

Page 1255 in the 5.0 workshop shows a high pressure pump for each rail. There's only one rail pressure monitor on bank 1, (1, 3, 5, 7). I'd lay money the pump for the even numbered cylinders isn't working correctly causing the injectors to self destruct. The injectors are probably just a symptom, not necessarily the problem.
 
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  #23  
Old 07-27-2017, 03:24 PM
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Originally Posted by Ranchero50
So they all failed on one bank? That's really, really suspicious.

Page 1255 in the 5.0 workshop shows a high pressure pump for each rail. There's only one rail pressure monitor on bank 1, (1, 3, 5, 7). I'd lay money the pump for the even numbered cylinders isn't working correctly causing the injectors to self destruct. The injectors are probably just a symptom, not necessarily the problem.
Totally agree. Thats what I guessed without knowing the specific components.
Is there a regulator in the chain-that failed??
 
  #24  
Old 07-27-2017, 03:46 PM
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Originally Posted by Queen and Country
Totally agree. Thats what I guessed without knowing the specific components.
Is there a regulator in the chain-that failed??
There are two high pressure pumps cam driven by an aux shaft next to the crank. They are supposed to put out @ 150 bar and the ECU used the FPR pressure reading to determine how long to keep the injector open to delivery the required fuel.

I'd definitely want assurance that both pumps were delivering the same pressure.
 
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  #25  
Old 07-27-2017, 04:12 PM
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Originally Posted by Ranchero50
There are two high pressure pumps cam driven by an aux shaft next to the crank. They are supposed to put out @ 150 bar and the ECU used the FPR pressure reading to determine how long to keep the injector open to delivery the required fuel.

I'd definitely want assurance that both pumps were delivering the same pressure.
I think pumps are fine- clue being shaft driven
The regulator under such high pressure is the thing I question.
 
  #26  
Old 07-27-2017, 04:20 PM
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Originally Posted by Ranchero50
So they all failed on one bank? That's really, really suspicious.

Page 1255 in the 5.0 workshop shows a high pressure pump for each rail. There's only one rail pressure monitor on bank 1, (1, 3, 5, 7). I'd lay money the pump for the even numbered cylinders isn't working correctly causing the injectors to self destruct. The injectors are probably just a symptom, not necessarily the problem.
My first guess was something went wrong with the the pressure relief valve on one of the pumps. Except the pumps are in parallel - see detail B drawing, page 1256 of the 5.0 workshop manual. That is why only one rail pressure monitor is used. So BOTH banks would see the same high pressure and I would expect similar problems on both sides.

I do agree that the injectors are a symptom and not necessarily the problem and it is really, really suspicious that all injectors failed on just one bank.
 
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  #27  
Old 07-27-2017, 04:49 PM
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I see that now, really crappy imagery in the manual.

Still smells that one complete bank would crap out...
 
  #28  
Old 07-27-2017, 06:04 PM
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I doubt that too much pressure, from the fuel pump side anyway, could damage an injector. The nominal fuel rail pressure is 2175 psi. I would expect the peak combustion chamber pressure to be considerably higher than what the fuel pump could develop so I don't think a faulty fuel pump could damage an injector.

The injectors are solenoid operated needle valves that will fail closed. I don't see how they could fill the sump with fuel when they failed. I can see an electrical/ECM problem keeping the injectors open and then burning up the injectors. I don't believe the injectors are the root cause.
 

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