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Q: The car has trouble starting - 2001 BMW 325i

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Every after few hours I try to start my car, the car doesn't start at once to be specific it starts and after 2-4 seconds it dies back and again I try the same repeats for up to three four times and later it tries to maintain its fire in engine and I checked with a mechanic he says the fuel pump and mass air fleow sensor need to be replaced but I tried to use air flow sensor cleaner and cleaned it three day back but still the same story repeats always but I just wanna ask and confirm with you weather shall I go ahead with mechanics suggestions to replace pump and sensor as I am worried they are much costlier when I go with Bmw original parts

My car has 111000 miles.
My car has an automatic transmission.

A: If the mass air flow sensor and fuel pump h...

If the mass air flow sensor and fuel pump have been verified as the cause or causes for the hard starting, then they should be replaced. When the vehicle is turned off, fuel pressure should be maintained in the fuel system so the vehicle will be easy to start the next time. If a faulty fuel pressure regulator or fuel pump check valve allow fuel pressure to drop when the car is off, then it will be hard to start.

It will have to be cranked longer or several times for the fuel pump to re-pressurize the system and start the vehicle. A fuel pressure gauge should be connected to the fuel system to see if the pressure drops when the vehicle sits for a period of time.

If the mass air flow sensor is faulty, cleaning it will not help. The system should be checked for any mass air flow fault codes stored. Any mass air flow sensor values/readings should be checked with a scanner to determine if the values are within BMW specifications.

I recommend having a certified mechanic, such as one from YourMechanic, come to your location to determine exactly what is wrong with the mass airflow sensor and replace it if necessary.

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