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Jay
Jay, Certified Infiniti Technician
Category: Infiniti
Satisfied Customers: 19083
Experience:  20+years, Nissan and Infiniti experience and currently now working for a Infiniti Dealer
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Infiniti QX56: Mike,I have a 2011 Infiniti QX56 with

Customer Question

Hi Mike,
I have a 2011 Infiniti QX56 with VK56VD engine (Direct Injection), I have a strange cranking problem, when the car is cold it starts normally, if i used the car for a while then switched the engine off, it will only start again within 20 to 30 min after shutdown, if i waited more than that it will crank but never start, the engine will only start after it cools down completely lets say 3 to 4 hours after shutdown.
Submitted: 1 year ago.
Category: Infiniti
Expert:  Jay replied 1 year ago.
Hello my name is ***** ***** Thank you for your question.
This is most commonly caused by a bad fuel pump. How many miles do you have on your truck and do you have a Service Engine Soon light on when the truck is running?
Let me know
Customer: replied 1 year ago.
Hi Jay,Thanks for your help,
Under more investigation, I have found out that the high rail pressure sensor (HRPS) reading INCREASES gradually from 2.9 MPA (required value at idle) to 15.1 MPA after the car is turned off in a time span of 30 minutes. I have done comparable testing in two other identical cars and found that their HPRS DECREASES gradually to values under 2.9 MPA. It seems that my mechanical pump isn't venting pressure, probably there is a problem with the inflow or outflow check vavle. Could you relate to this?
Regards,
Ahmed
Customer: replied 1 year ago.
And one more question.Which fuel pump do you think is problematic. The Mechanical in the engine compartment or the electrical inside the tank?Your help is greatly appreciated.
Regards,
Ahmed
Expert:  Jay replied 1 year ago.
The main fuel pump is the most common, I have seen direct injection pumps go also, but not nearly as the main fuel pump. I asked if you have a Service Engine Soon light on. You never told me? I also asked how many miles were on the truck. Please let me know, if you have a code. The code could tell me everything that is going on. Let me know..
Expert:  Jay replied 1 year ago.
Hello?
Expert:  Jay replied 1 year ago.
If you have any more questions on this, please feel free to ask. If not, and you're satisfied with my help, please Rate me. I hope I have provided you with Excellent Service. Thanks Jay!