so ran across this issue at autozone. My friend is having issues with his 99 yukon and I think its the fuel pump. He had it replaced a couple weeks ago but he purchased a fuel pump from autozone. He just picked one of the two offered. One had code GFU the other has code GFV. What does this all mean? The pump he had was aftermarket so no markings of GFV or GFU. Where can we locate this info? Thanks!