GMC "GOOFY MOTHER..... COMPANY"
Loads of issues for ever with fuel tank fuel pumps. Fuel regulators, pumps, filters issues galore.
You hear that noise because you have an injected engine that requires a constant fuel pressure, applying the switch turns on the pump so the regulator can tell the computer there is sufficient pressure to allow it to start the engine and run. The filters often clog and create abnormal demands on the system. The pump pumps it's little guts out and the regulator strains it's self to death.
You can replace the fuel filter, the pump, and the regulator and still have issues possibly. The gas tank has to be dropped to do all this. Worse? Tailpipes and fuel lines disconnected.
Need I say expensive? Wonder why I call GMC "Goofy Mother.... Company" ? Great trucks tell you get a fuel line issue or other issue?
GMC outsources from Mexico and other places (China) for these fuel pumps and regulators. They started becoming an issue after trusted American made parts were dropped just like many things. The quality controls GMC has in Mexico are horrendous. Other manufactures have Mexican made parts and some complete manufacture. Suprisingly they can manage better/superior quality control. It's not a Made in Mexico issue it is a GMC issue. They have been relying on production over quality for far too long when others have been focusing on quality and production in unison and harmony.
The UAW warned us about this and we griped about their wages ignoring them. We are ultimately responsible for wanting lower cost. You get what you pay for. With GMC it's clear........ What's worse is GMC designs, they just don't care how stupid their designs can be. Yes. I don't like GMC and I am prejudice. You find out how much owning a GMC product will cost when it starts hitting 50k or more. Unfortunately you are finding out early but don't feel alone, these issues are shared and common.