In-tank fuel pump
Moves fuel from the tank toward the engine.
Usually in a serviceable module inside the fuel tank.
An electric pump provides supply flow; pressure regulation and control vary by fuel system.
The first relay runner supplying the next pump.
Long cranking or power loss may reflect supply pressure, electrical control or fuel quality.
Plugs and filters use engine-specific service guidance. Pumps and injectors are normally assessed through pressure, leakage and electrical tests.
Spark-plug service is usually less involved than direct-injector or high-pressure-pump replacement; coding and access can add work.
A BMW direct-injection system can have both a tank pump and an engine-driven high-pressure pump.
BMW combustion models; spark components are petrol-only and glow-plug hardware is diesel-only.