Preparation For Testing

All CIS systems are very sensitive to air leaks. Check condition of rubber boots, hoses, and gaskets. Other areas of leakage are injectors, cold start valve, and PCV system (filler cap and dipstick).
Install a pressure gauge to perform fuel pressure tests. On all models, pressure gauge is installed between the control pressure regulator and the center fitting on fuel distributor. See Fig 1.

Fig 1: Pressure Gauge Installation
Courtesy of AUDI OF AMERICA, LLC

After installation, bleed pressure gauge by opening and closing valve several times.
To operate fuel pump with engine not running, disconnect fuel pump relay from relay panel (VW, Porsche, Audi, Saab, Mercedes-Benz). Insert a jumper wire into sockets that correspond to terminals 30 and 87 on relay. See Fig 2.
On Peugeot, remove steering wheel and lower left dash panel. Install switch and harness (8.0141P) to tachymetric relay connector, or jumper across terminals 30 and 87B. See Fig 2. On Volvo, Mercedes-Benz, and other models so equipped, disconnect safety switch connector on air flow sensor.

Fig 2: Jumper Wire Connection For Fuel Pump Testing
Courtesy of AUDI OF AMERICA, LLC

Saab shown, other models similar.

Fig 3: Checking Air Flow Sensor Operation and Alignment
Courtesy of AUDI OF AMERICA, LLC

Directions given for moving sensor plate apply to engines where air flow lifts sensor plate UP. Reverse directions if servicing an engine where air flow pushes sensor plate DOWN.
Operate fuel pump on Peugeot by depressing switch on harness. On all other models, turn ignition on. Place pressure gauge as low as possible in engine compartment, then open and close valve 5 times to bleed gauge. Place valve in open position and hang in convenient location. Turn pump off.