Checking the fuel injection system (Opel Vectra B)

If a fault has occurred in the fuel system, first check that all electrical connectors are securely connected and protected from corrosion. Also check the cleanliness of the air filter, the condition and gap of the spark plugs, the correct adjustment of the valve clearances, the compression in the engine cylinders, the setting of the ignition timing angle and the cleanliness of the air supply hoses to the engine. If the initial actions do not help to identify a fault in the fuel system, then it is necessary to check and repair the fuel system at a service station.

Source is on the website www.opelbook.ru