Question about 1988 Nissan 300ZX

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I have a 1988 300zx non turbo 3.0 just replaced the ecu thinking it was the problem but its not. My car will turn over and it sparks, tested the fuel pressure and it makes 42lbs so thats not the problem the injectors just wont spary. The self diagnosis lights on the ecu dont come on. Makes me think its not getting power is there a hidden fuse, relay or fusible link before the ecu? Completely lost

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  • snakeeye253 May 30, 2011

    earth pulse? does that mean it grounds on one side? Can i test that with a test light?

  • snakeeye253 Jun 01, 2011

    I will try while cranking it over. I unhooked the wire clip onto the injectors and tested with a light both sides are constantly hot even with the key off I will go try it while its turning over and post results. I am not sure if both wires are supposed to test hot either. The ones that go to the injectors the green and red ones both light up the test light, on both sides of the engine even when the key is off. It ran perfect I had a stage 2 clutch put in it. It drove 2 miles home and the fuel pump would not shut off, It drained the battery i recharged it and found a short that was keeping it on in the trunk and now the injectors wont spray. Have pressure in the fuel rail and spark. checked the timing belt that is still good. completely lost any help would be appreciated.

  • james mcgrath Jun 12, 2013

    if you download the work shop repair manual it will show you how to test every thing and tell you what the problem is ok i have the same problem i did this test and it came back as the idle switch sensor so if you go to the car turn the on to dash lights then on the bottom of the compute

  • james mcgrath Jun 12, 2013

    if you download the work shop repair manual; and go to the diagnostic procedure it will show you what to do ok this is what to do go to car turn it on to dash light then on the bottom of the computer turn the screw all the way around then count how many times the red and green lights flash the red flash are lots of 10 the greens are 1s

  • james mcgrath Jun 12, 2013

    if it flashs 2 red and 3 green that is 23 this will tell you what is wrong so download the manual you will sort it out i have the same problem i did this and it was the idle switch sensor

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The pulse to switch the coils comes from the crankshaft sensor via the ecu. Pulse to switch injectors comes from the CAMshaft sensor via the ecu. Check injector wiring plugs and confirm there is an ignition live of 12v at one side. Other side should have an earth pulse when cranking.Once you know which is missing you can trace the fault backwards. ( if no ignition live then check wiring, relay, fuse etc) if no earth switching check camshaft sensor and wiring.

Posted on May 29, 2011

  • 1 more comment 
  • snakeeye253 May 30, 2011

    I used a 12v test light and my injectors on one side have power even when the key is off. Is that right?

  • Martin
    Martin May 31, 2011

    Yes. That means it will have ignition +ve at one side and a flashing ground at the other side while cranking.
    You say constant power at one side. Do you mean it has a +a2v or a ground. Do you have a flashing ground at either during cranking?

  • Martin
    Martin Jun 01, 2011

    Hi we need to be clear about this.
    Disconnect one of the injector plugs. ( 2 pin plug)
    Switch on ignition and immediately probe the plug and find the positive side..
    One pin should be ignition live (+12 volts)
    Then probe the other pin whilst cranking the engine.
    This side should show a pulsing earth (ground).
    Ideally you should be using an led test light and not a filament type test lamp, as the switching current may not operate a bulb type. If you are using a single polarity led test lamp, remember to connect the clamp end to ground to probe for a +ve and vice versa.
    Let me know what you find.

    In answer to your earlier question...No you should not have power ot the injector when key is off. Thats why i'm wodering what kind of tast lamp you are using and if perhaps you are connecting the clamp end to +ve and probing and finding a ground.

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happy means:
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