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Thread: No fuel coming out of injectors. Diagrams?

  1. #1
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    No fuel coming out of injectors. Diagrams?

    Truck in question is a 89 S10. The two TBI injectors are not spitting any fuel. At first look we guessed one of the possible reason was the state of the connectors:


    So we ordered new connectors but managed to forget which wire goes where. I am assuming here the circuit is: once engine is on, 12V is provided to the injectors and the ECU then will ground the other wire to open them. I am also assuming, because I do not have the diagram and because of the nature of TBI, that both injectors fire together, so it is possible there is really only one 12V wire and one ground wire down the harness. I could be wrong, but, without a diagram that is all I have to play with. In any case, using a multimeter, we thought the power wire was the pink (or whatever you call that colour) with a black stripe wire and the green and blue wires were the grounds to ECU. Based on that, this is how we wired it up:




    When we tried to crank, nothing happened. Well, we are getting 12V at the red wires, but the green and blue wires are not grounding as the engine turns. What did we do wrong? Does anyone have a diagram we could check? We are trying to get it running tomorrow morning otherwise we need to grab my car dolly before the apartment complex call the tow company to make it go away; they have already left a notice on the car today.

    Thanks!
    Last edited by Bone Crusher; 07-26-09 at 09:45 AM.

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    Re: No fuel coming out of injectors. Diagrams?

    I looked at my 89 just now-
    from left to right-just like your pic, red,blue,white,green-order mine are in
    just the oposite of your pic-does it matter? not sure

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    Re: No fuel coming out of injectors. Diagrams?

    Check the ECU fuses. I am pretty sure the injectors are polarity independent.
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    Re: No fuel coming out of injectors. Diagrams?

    Danz, thanks for the info; it kinda reinforces my original guess: red is for power and blue and green are for ground. My friend -- the truck owner -- said the green and the blue wires were connected to one of the injectors. That could mean a lot of things, one of which is the PO was rigging the wiring somehow. I would like to get it right and reliable. Right now, the most important thing is a diagram so we can follow those bloody wires.

  5. #5
    87wildside Guest

    Re: No fuel coming out of injectors. Diagrams?

    The blue and green go to the ECM
    Red and white go to the ECM/IGN fuse which is 10A
    Blue and red go to one and green and white the other.

    From the pictures I found on the web looks like the wires from left to right are; red, blue - white, green.




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    Re: No fuel coming out of injectors. Diagrams?

    I'm curious, when did the problem start and what was the symptoms?
    Because, when an ignition module goes bad, even though you will hear the fuel pump prime, the injectors will not spray because the computer is not telling them to. It will just crank and not fire.

    BTW, welcome to the Planet. I hope we can help you out!
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    Re: No fuel coming out of injectors. Diagrams?

    87wildside, thanks for the picts. So, I am kinda close as far as the wiring is concerned. That said, I have not seen the white wire in the engine harness. What we did find out was both power wires were spliced off the red/pink/whatever wire, which is what I tried to replicate. Of course, either that will work or may be the cause for the 10A fuse to be open and for the burnt out injector connectors. But then again, it seems this truck had an engine bay fire before. I do not know the details including how large it was but that is what I know.

    Tink, that is a bit how I was thinking. Well, I do not know much about GM systems so I was basing my though process on Bosch Jetronic: a Hall sensor on the distributor talks to the ignition module, which amplifies and send it to the ECU. The ECU then uses that signal to know (a) the engine is spinning (i.e. it is ok to turn fuel pump and injectors on) and (b) when to fire the injectors. The ECU should power the pump and injectors by grounding a relay (or two) and it fires the injectors by grounding them. The ignition module fires the coil by grounding the primary wire that does not provide power. So, if as you said the ignition module is not happy, it will not tell the ECU the engine is alive and well, so the ECU will not let the injectors get powered.

    If I had a diagram, I would check for the signal coming from the ignition module to the ecu at the ecu connector. I guess I can also check for voltage and pulsing voltage on the primary side of the coil; is there a way to remove the coil itself from the circuit so I can see if it is getting a signal? How about the signal from the Hall sensor? I so far have not found the connector from the distributor to the ignition module. Also, would you know which pin number is the one for the signal comf the ignition module to the ECU? Now, if this was a Bosch system, you could ground one of the wires to the hall sensor to make it think the engine is spinning and, as a result, fire the injectors. Can you do that?

    I know my questions are many but I would like to make sure the ignition module is at fault before just replacing it.

    And, thank you for the welcome. Another s10 site seems to have some users whose reply is more like, "how come you do not know this?" than actual useful help.

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    Re: No fuel coming out of injectors. Diagrams?

    make sure the 2 plugs are plugged in at the backside of the distributor. Had this problem with my 90 Sierra. Plug was rotten and made a poor connection.

    Jay

    If at first you don't suceed, cheat, repeat untill caught, then lie

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    Re: No fuel coming out of injectors. Diagrams?

    My pick up coil was bad, so my injector would not fire. I have a CPI truck though, so I'm not sure it's the same.
    The world will drive you nuts if you let it.

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    Re: No fuel coming out of injectors. Diagrams?

    I hope this is readable VVVVVVVVV



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