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Anthony
Anthony, Chevy Technician
Category: Chevy
Satisfied Customers: 11750
Experience:  GM Certified
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I have a 2012 Sierra Denali that has been deleted and tuned.

Customer Question

I have a 2012 Sierra Denali that has been deleted and tuned. It has an airdogII gp165 4G lift pump. It has been tuned since 32,000 miles, and has set P0087 since the day it was deleted and tuned. Is there an FPRV, and if not, what could be causing the code?
Submitted: 9 months ago.
Category: Chevy
Expert:  Anthony replied 9 months ago.

Hello!

Sounds like the fuel rail is bad and returning too much fuel causing low pressure at high rpms.

Here's the test for it:

1. Measure return flow from the FPR 2 port on the front LH fuel rail, (return hose removed and plugged). Place a hose on the port on the fuel rail, and place the other end into a container (fuel can).

2. Start and run the engine. With engine at operating temperature, hold RPM at 1800 RPM, measure return flow from the FPR 2 for 15 seconds.

3. If more than 10 ml, replace the fuel rail assembly on the LH side.

Customer: replied 9 months ago.
What causes the fuel rail to return fuel. Does it have a preset mechanical relief valve, or is there an electronic electromechanical valve.
Customer: replied 9 months ago.
wouldn't that be suspect before the rail? Just asking because I have no idea how the rail works. I'm assuming from your answer that the rail is non-serviceable, but I want to make sure.

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