The high-pressure fuel pump (HPFP) on the FSI/TFSI GTI is cam-driven off the intake camshaft and is a known wear item — often alongside the cam follower that rides between the cam lobe and the pump. Low rail pressure throws long-crank, stumble, limp mode, and fuel-pressure codes, sometimes with cam-timing faults. Always inspect the follower when you touch the pump — see FSI Cam Follower HPFP and Cam Follower Check DIY
…