Modern fuel systems fail in ways that mimic other faults. A weak in-tank pump causes a lean code at high load rather than a no-start; a leaking injector seal produces a misfire that moves between cylinders; a clogged evaporative canister turns a fuel smell into a hard-start after refuelling. Because fuel is pressurised and, on direct-injection engines, delivered at several hundred bar, every component in this group should be replaced with the ignition off and the system depressurised.
Sending units are matched to tank depth and connector type, and injectors to flow rate and connector style. Confirm the engine code and the production date before ordering, and never mix injector part numbers across banks on a direct-injection engine.
