If when you turn the key the engine turns over normally but will not start, there can be any number of reasons for this problem.

Some basic checks will need to be done to diagnose this problem.

1. Do you have fuel pressure.

Some cause of low or no fuel pressure are a plugged fuel filter, faulty pump relay, blown fuse, bad fuel pump. Different makes and models require different fuel pressures to start. Refer to a manual for the proper pressure for your application.

2. Is there sufficient spark at all the spark plugs.

No spark can be caused by many things. A faulty sensor, computer, ignition module, etc. Spark on some spark plugs can be caused by faulty ignition coil, spark plug wires or the plugs themselves.

3. Do the injectors fire and spray fuel into the engine.

No "Fuel Injector Pulse" can be caused by a faulty computer, wiring, or a computer. Pulse can be tested with a special test light. If the test light blinks, then the injector should fire. If not, then a plugged or failed injector is the cause. There are several special tool / tests to check the injector system.

4. Is the engine mechanically capable of starting.

Checking the internal components of the engine is required. Check for compression, see if the internal parts such as the Camshaft are turning, etc. There are also many tools to do these tests.

Question: Car cranks but wont start or stay running. Changed sparks plugs,coils ,crankshaft position sensor, camshaft senor.

Answer: You need to tell us what make and model vehicle you are asking about. This could be many different things wrong with your vehicle, and some are make and model specific. In general, you need to know if you are getting spark and fuel. Just changing all these parts does not help since we don't what the engine is missing.

If you have spark, then you need to find out if you have fuel pressure and fuel injector pulse signal. If no fuel pressure, there could be a bad fuel pump. If no fuel injector signal, this could be a bad PCM. Is the theft or security light on? If so then that is where your problem is.

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Comments (31)
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  • Guest - Rick

    I have a Buick Allure 2005 will not start. Installed new fuel pump checked fuel relay. The fuel pump is not turning on. Car cranks over no problem will run till all fuel is out of the fuel line then cranks but no fire. I can tell the fuel pump is not running. But changed it anyway. Nothing on the diagnostics. Can't find any electrical break but have not traced wires all the way to the fuel pump. Any help??

  • Guest - Jack

    In reply to: Guest - Rick

    You need to check for power and ground to the pump to decide what side of the circuit to diagnose. Purple wire should be hot, black should be ground.

  • Guest - Anna

    I have a 2001 Ford F150 Super Crew Lariet. I have replaced the Battery last week, but it tries to start and then does nothing, then I wait a few minute's and do it over again, sometimes it starts and other times I doesn't. Don't want to be taken advantage of because of being a woman, need to know what direction to go in

  • Guest - Bruce

    Have a 2006 Buick Rendezvous 3.5 motor fuel pumps running fuel pressure it's good new plugs new wires no fuel coming out of return will not crank

  • Guest - Miranda Price

    I have a 1999 murcury Tracer that will crank but want stay running . its not fuel pump or regulator changed filter its getting spark checked all plugs and wires bought a new battery. And my check engine light has never came on. Could someone please throw out any new ideas I can try

  • Guest - rick

    2004 buick rendevoue starts cold when hot cranks but wont start intermittently no spark

  • Guest - Melissa d Norris

    2004 ford e450 v10 class c motorhome.... cranks but won't start...we have 1. Changed the crankshaft sensor 2. changed the PCM 3. Camshaft sensor 4. Replaced the fuel Pump 5. Replaced the computer (again) 6. changed the ignition switch 6. checked the Mass air flow sensor. Have also check relay , fuses and wires.
    we have placed Noid light on Fuel injectors... it will flash ONE time only when cranking, until you turn the key off and do it again, then repeats the one time only. any Ideas????