99 Ford Mustang Gt Problems

Discussion in 'SN95 4.6L Mustang Tech' started by FORDGT99, Mar 11, 2014.


  1. FORDGT99

    FORDGT99 New Member

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    I have a 1999 ford mustang gt with the 4.6 sohc 2v and i m having problems getting it to start its getting fuel, air, it has the right compression and everything acts like it wants to start but doesn't kick over all the way
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  2. bigc2330

    bigc2330 Member

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    Is the theft light flashing?
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  3. FORDGT99

    FORDGT99 New Member

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    Yes when the key is out it flashes but its not a theft problem I reset the theft thing the way the dealership tells you too and it did nothing for me I've checked over everything at least twice but I'm going to go back this weekend and double check my timing
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  4. wmburns

    wmburns SN Certified Technician

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    Confirm that all fuses in the engine bay and driver's kick panel have been CONFIRMED good.

    Turn the key on but do NOT crank. Does the theft light go out after a 3 second "prove out"? If not, STOP and find out why

    Cycle the key off/on/pause several times WITHOUT cranking. Do your HEAR the fuel pump run each time? If not, STOP and find out why.

    What happens if the throttle is held half way open during cranking?

    What happens if the electrical connector to the MAF is disconnected?

    How are you planning to "check timing"? Explain.
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  5. FORDGT99

    FORDGT99 New Member

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    I've checked all the fuses in both places and they were all good. And the theft light does go out after 3 seconds my fuel pump kicks on every time and if I open it about half throttle it acts like it wants to start more but nothing. And maf? And opening up the motor by the pulley system and making sure everything is at top bed center I have the chiltons manual that tells you how to do it and a mechanic as a friend to help
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  6. wmburns

    wmburns SN Certified Technician

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    What about disconnecting the electrical connector to the MAF?

    Are you positive there aren't any vacuum leaks especially in the intake tube between the MAF and throttle body butterfly? What about the PCV system? All vacuum hoses in good shape?

    Confirm there is key on +12 volts at any fuel injector Red wire. If no voltage, STOP and find out why.

    Have you MEASURED the fuel pressure at the rail?

    Confirm that the electrical connector to the fuel rail pressure sensor is clean with no bent/pushed pins. Measure the key on voltage between the BN/WH andGY/RD wire. Post.

    Do you have an ODB2 scanner that is able to monitor operational data? If so, monitor RPM's during cranking. Do the RPM's change? If not, suspect a CKP sensor problem.

    Use the ODB2 scanner to monitor MAF airflow during cranking. Does it change? Post the range of values seen during cranking.
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  7. FORDGT99

    FORDGT99 New Member

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    I'm getting 12.5 12.6 volts and I've ran an obd2 on it And its just telling us stuff that we already know about and its all stuff we can get by without hooking up and its recamended for 35-55psi of fuel and I'm getting 45 the sensor is good just got it the other day and my coils are getting .08 resestans and my injectors are getting the correct oms
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  8. FORDGT99

    FORDGT99 New Member

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    And what do you mean maf
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  9. wmburns

    wmburns SN Certified Technician

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    MAF=Mass Air Flow sensor. If you don't know what a MAF is........ Google?

    Should I assume that you are seeing 12 volts across the fuel rail pressure sensor? 12 volts at the fuel injector Red wire?

    What about the ODB2 RPM's?

    What does the ODB2 scanner say the fuel pressure is?

    Have you used a "noid" tester to confirm a fuel injector pulse? Measuring the resistance (Ohms) of the injectors isn't going to give the whole story.

    How long have you been working on this problem? What happened to the car before this problem started? Any recent work/upgrades/repairs?
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  10. FORDGT99

    FORDGT99 New Member

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    Yea I have the mass air flow sensor and the obd said fuel pressure was 45psi and yes have used the noid tester and I've had the car for almost a year got it with just a body and tranny put a motor out of a 98 crown Vic in it and don't remember what the obd was saying about rpms i will be able to check again when I'm with the car this Saturday
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  11. wmburns

    wmburns SN Certified Technician

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    So the motor has never started after the repair.

    Confirm that the ground braided strap between the left hand motor mount and the frame rail has been installed.

    I believe you have stated the compression is OK. However, has the motor been re-timed as part of this work? If so, explain HOW the timing was done. Don't just say, "followed manual". Why is this important? Because it is possible to time a 4.6 180 degrees out of phase. This is a difficult problem to isolate because the motor WILL have good compression.

    Also note that if there's 12 volts across the fuel rail pressure sensor this is a problem. The reading should be around 5 volts.

    I'm trying to find out what are the values reported to the PCM by the MAF. Why is this important? Because if the values are out of wack low, then the PCM will not inject enough fuel. That's what the test to disconnect the MAF does. Once the PCM sees that the MAF is electrically disconnected, the PCM will replace the missing MAF values with "default" values. Sometimes these default values are good enough to start the motor.

    Sappy saying for the day:
    There's no elevator to success. You have to take the steps.
    Last edited: Mar 11, 2014
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