Air In Fuel System

WARNING: This page is about a different car, the 2005 Jeep Liberty. However, it is still accessible from the selected car via links, so may be relevant.

Air will enter the fuel system whenever fuel supply lines, separator filters, injection pump, high-pressure lines or injectors are removed or disconnected. Air trapped in the fuel system can result in hard starting, a rough running engine, engine misfire, low power, excessive smoke and fuel knock.

Inspect the fuel system from the fuel tank to the injectors for loose connections (Refer to WARNING ). Leaking fuel is an indicator of loose connections or defective seals. Air can also enter the fuel system between the fuel tank and the fuel filter. Inspect the fuel tank and fuel lines for damage that might allow air into the system.

Trapped air or leaking lines may also be identified by placing a clear piece of fuel line between the fuel supply hose to the filter and the fuel supply hose to the high pressure pump. If a steady stream of large air bubbles are visible in the clear hose while the engine is cranking or running the air intrusion is occurring before the high pressure pump.

With the scan tool connected to the vehicle, select Engine and then select Sensor Display. Page down to view Fuel Pressure Set Point and Actual Fuel Pressure. Start the engine and observe the Fuel Pressure Set Point and the Actual Fuel Pressure. If the Actual Fuel Pressure Oscillates above and below the Fuel Pressure Set Point in a regular cycle, inspect the fuel system for air intrusion.

If the Actual Fuel Pressure gradually drops below the Fuel Pressure Set Point then spikes well above the Fuel Pressure Set Point, replace the fuel rail pressure solenoid (Refer to FUEL SYSTEM/FUEL INJECTION/FUEL PRESSURE SOLENOID - REMOVAL) .