Engine light on - high pressure fuel pump failure? PIP5590A

mchnhd4 · June 9, 2019

I have a 2014 5.3 Sierra and the engine light has come on recently. Took it to the dealer and codes P0172 & P0175 codes came up for injectors running rich. Dealer tested everything and fuel flows and everything is spot on. At times the truck idles rough, has a hesitation off idle, and shifts hard up and down. The shifting I was told is the computer going to a fault mode when it senses loss of power. The dealer found a PIP5590A bulletin and the symptoms are exactly what I describe and points to the high pressure fuel pump failure. The problem is the symptoms come and go along with the engine light. It will run like hell and then when the ignition cycles of and back on, the truck runs fine again. The cost to fix this is $1250. Im hesitant to throw the money at it. Dealer said if you can bring it to us while the symptoms are present, we can confirm its the hp fuel pump or not. Anyone every heard of this failure or symptoms?

silveradosid · June 10, 2019

i dont think you would have codes for running rich if hp pump was failing, if the pump is failing then it should be harder to start

tbarn · June 10, 2019

Most of the high pressure pymp failures are from leaking fuel into crankcase. Pulling fumes in through pcv system.

mchnhd4 · June 10, 2019

33 minutes ago, tbarn said:

Most of the high pressure pymp failures are from leaking fuel into crankcase. Pulling fumes in through pcv system.

So is the pump technically failing then or is the problem elsewhere? It comes and goes which is baffling.

mchnhd4 · June 10, 2019

34 minutes ago, tbarn said:

Most of the high pressure pymp failures are from leaking fuel into crankcase. Pulling fumes in through pcv system.

Forgot to mention the dealer did check the crankcase and found no fuel

newdude · June 10, 2019

26 minutes ago, mchnhd4 said:

Forgot to mention the dealer did check the crankcase and found no fuel

Per the PI though, fuel won't or very little will be found in the oil.

Quote

#PIP5590A: Diagnostic Aids For P0172 and P0175

Correction

If SI does not Isolate the cause of the rich condition the following may be help full.

Disconnect the dirty air side of the PCV system

Plug the vacuum supply

Start the engine and monitor the fuel trims in closed loop.

If the fuel trims return to normal this is a good indicator that the high pressure fuel pump is leaking.

With this concern we do not see a lot of fuel in the crank case, so changing the oil may not isolate the concern.

When the high pressure fuel pump leaks the PCV will pull the fuel mist straight into the intake causing the concern.

Note: This is a preliminary temporary diagnostic and repair.

As more investigation information becomes available this PI will be updated or advanced to a bulletin.

mchnhd4 · June 10, 2019

17 minutes ago, newdude said:

Per the PI though, fuel won't or very little will be found in the oil.

Awesome thank you for that. Since the condition (stumbling, rough idle, and engine light) seems to come and go, is my best bet to get it to the dealer while its happening? Then they should be able to confirm or at least isolate the cause and repair it.