Currently working on my neighbor's 2014 GMC Sierra 1500 5.3 with a running rich condition. After following the technical bulletin including our fault code we found that the high pressure fuel pump is leaking fuel into the engine. I found the part but my neighbor is looking for a cheaper option. I've searched and searched for rebuild kits but I'm having no such luck. We're going to let it sit for now and hopefully we can find a kit. I plan on pulling and old off at a junk yard to tear down and see what we're dealing with.