Fuel Pressure Test

A gauge connects to a test port on the fuel rail or in the supply line. Running pressure, pressure under load and hold pressure after switching off are checked. High-pressure direct injection systems are checked with live data instead. A pressure drop after switching off can point to a leaking injector or check valve.

Readings are compared with the manufacturer's values to show whether supply, regulation or leakage is the problem.

Fuel is highly flammable; avoid sparks, wear eye protection and catch any spill. Never open direct injection high-pressure lines until the pressure has dropped.