Po422 and suspect weak fuel pump. 2017 chevy Silverado 5.3v8

Dallas Fisk · June 27, 2020

Hello, I have a 2017 chevy silverado 4x4 with the 5.3 v8 it recently thew the engine light on and upon further exam it is reading po442 evap leak, small leak detected. And also when this started happening, when the vehicle is cold. Meaning sitting for 3-4 hours it cranks for an extended period of time before starting. I've been experimenting with stuff and I've discovered if you cycle the ignition key 2 times, it starts as good as it always did before this problem happened. I've come to the conclusion I've got a failing fuel pump and cycling the key is priming the system then it builds fuel pressure and starts right up. Now would a fuel pump also throw a po442 engine code as well? Or is that code related to something else acting up. Also, if indeed this is a fuel pump which one would likely be the culprit? In tank pump or the on engine pump? Also I must add my scanner is registered 46-52psi fuel rail pressure and it runs just fine other than the starting issue. What are your thoughts? Have a good day.

CamGTP · June 27, 2020

Small evap leaks are normally from the gas cap and unrelated to this other issue. A smoke test would be best to determine that. Or just clean the metal fuel neck and clean the rubber gasket on the cap, clear the code and see if it comes back.

Your pump isn't exactly failing as it still works fine to keep the low side pressure high enough while running. There may be a thing going on with the regulator/check ball bleeding off pressure quicker than it should. Priming the system twice like you have been doing is allowing it to pump the fuel line back up then build enough pressure. The high side pump is mechanical and turn that pressure into 1,000-3,000psi.

Pretty sure you'd have to replace the whole fuel pump assembly in the tank, would be pretty spendy.