Question:

I have a 1990 f150 ford and i just put a fuel pump on it and a fuel filter and a fuel modulator and a electron

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i changed the fuel pump and fuel modulator and fuel filter and electronic modulator and coil and starter and alternator and battery ,and if i put ether in the airtake it will start but won,t start with out it all it wants to start but won,t can some one help me please.

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  1. Ok I have to ask if you have spark? If not then you may have to change the PIP inside of your distribtor.It will have to be removed and diassembled to install it.Hope this helps.

    If getting spark then can onlythink that injectors are not working or clogged/stopped up or PCM is not commanding the injectors.


  2. Considering all you have done and checked your problem is most likely either a wiring issue or the PCM is shut down due to a shorted sensor.  The first place to start with diagnosing this issue is to find a scanner that will work on the EEC4 engine control system on your vehicle, retrieve the codes, right now it doesn't matter what they are as long as you get them, from what you are describing I doubt you will get any codes.  If this is the case you have most likely have a failed sensor on the engine causing the VREF circuit to short to ground and shutting the PCM down, this in turn shuts the fuel injectors down, you will have spark but no fuel.  Diagnosing this concern is quite easy, unhook the engine sensors 1 at a time and try to start the truck, the sensors that use VREF are MAP, TP, ECT, EVP, IAT and Knock sensor. (any sensor with3 wires except O2 sensors) If you do get codes you will need to trace down the primary and secondary fuel pump circuits and find the problem.

  3. This will sound crazy, but why don't you do some diagnosis instead of changing all this stuff.  Wasn't that expensive?

    Here's step one:  Check your fuel pressure.  Let us know how that works out.

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