PETROL INJECTION Make sure the fuel pump runs for a few seconds after the ignition is turned on. Crank and check for a spark at the plugs. Check all injector plugs are firmly connected and rust-free. Check wiring.
DIAGNOSTIC SYSTEMS If the car has an OBD diagnostic system, find out what it thinks is wrong. Bear in mind that a ‘faulty sender’, or similar, is far more likely to be a faulty connection after a period of standing idle.
DIESEL WOES Glow plugs should be warm to the touch after operating. Check the circuit/relay if they all stay cold. Injection can be foxed by a blocked filter, cold and waxy diesel, or gums and resins from cooking oil.