You need to start suspecting if the fuel pump is not delivering adequate fuel pressure and volume to the engine, this may cause the engine not to start or run properly. This can be as a result of low fuel pressure which can cause hard starting, a rough idle, misfiring, hesitation and stalling. No fuel pressure will prevent the engine from starting, or will cause the engine to quit running if the fuel pump fails while driving.

Fuel injected engines are very sensitive to fuel pressure as well as fuel volume. Low pressure will cause starting and driveability problems. A pump that can deliver adequate pressure but not enough volume may allow the engine to start and idle normally, but it will starve the engine for fuel and cause a loss of power when the engine is under load, accelerating hard or cruising at highway speeds. Lets look at some situations where fuel pump can cause problems to your vehicle working condition:
Engine Cranks But Will Not Start
A dead fuel pump can prevent an engine from starting, but so can a problem with the ignition system or the engine itself (such as a broken timing belt).

The first thing to check would be spark. This can be done by connecting a spark plug tester to a plug wire while the engine is cranking. The tester must be grounded to the engine block for a good electrical connection.

CAUTION: Do not touch any of the spark plug wires while the engine is being cranked because this can cause a bad shock!http://automedicsafrica.com/know-wrong-vehicle-fuel-pump/