Fuel supply

How a demand-controlled fuel system is built: two circuits, the pump module in the tank, the fuel pump control unit, the low-pressure sensor, pressure at start-up, pressure retention and limiting valves, the diesel transfer pump and fuel preheating — with examples from different engines.

How the high-pressure pump of a direct injection engine is built and works: cam drive, demand-controlled delivery, the intake, spill-back and delivery cycle, two valve control principles, failures and protection — with examples from different engines.

How an activated charcoal canister collects petrol vapors from the tank, how the purge valve and the control unit send them into the engine, where the vapors enter on a turbocharged engine and how the self-diagnosis checks the system — with examples from different engines.

A low-pressure circuit without a sensor or valves and a PWM-controlled pump in the tank, a high-pressure pump with a roller tappet on a four-lobe cam, the N276 regulator, the G247 sensor, an integrated bypass and the benefit of four cam lobes.

Demand-controlled feed without a return line at 3.5–6 bar, a high-pressure pump with a four-lobe cam and roller tappet, 50–150 bar control by the N276 valve, a 200 bar limiting valve and a damper in the pump.

How a short current pulse on the N276 regulator sets the delivery of the high-pressure pump over four phases of the piston stroke, and why a six-jet multi-hole injector is better than a swirl injector.