Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Electronic fuel injector

  1. Oct 2, 2006 #1
    hello everybody
    my ques about the fuel injector,which is working electronically--
    i saw it for real in a car was fixing by a mechanic,and i looked at the electronic fuel injectors mounted on the fuel rail----and while the engine was running,the injector as u know-is supplied by the pressurized fuel from the fuel pump through the rail to the injector and its controlled by the ECU,to calculate the pulse width-,anyway my ques is completely imperical-:)--
    i found two wires installed in every injector----what are these two wires?
    when i removed it and came with a lamp and while engine was running i installed the two wires i took from the lamp in the cable comes from the ecu to the injector,the lamp turned on-and when i reversed the wires it also turned on--!!
    before i do this test ,i thought one wire is the vcc-(electricity feed)to the injector-and the other is the ground
    now-im confused-cuase to make the lamp turn on it must connected to two terminals(one is positive and the other is negative which is a ground)
    that what i was thinking,but i dunno if im right-cuase im not good in electrecity or electronics-but i know a little
    i wanna know how can i test this injector?with avometer?to check if the ecu already send the signal to the injector to work or not.
    thanks for any help
  2. jcsd
  3. Oct 3, 2006 #2


    User Avatar
    Science Advisor
    Gold Member

    Firstly, a warning, speaking from not-quite personal experience.

    Don't piss around with fuel injection systems unless you actually, really, genuinely know what you're doing.

    Assuming you've accepted the above, carry on reading.

    Now, from what you've described (having given no indication of the type of engine, type of application, or type of fuel system), I'll suggest that one terminal will be +12v feed from the battery, the other will go to the ECM for injector control. Obviously this may depend on type of engine and injector, so don't take it for read. Again, if you genuinely know what you're dealing with, you probably didn't need to ask that question.

    I don't mean to be patronising, but messing with FIE can be fatal in quite a number of ways.
  4. Oct 4, 2006 #3
    the light bulb has no directional bias
    it matters not how it is hooked up
    the light bulb just is showing current flow
    not it's direction

    if the injector fires [clicks] but no gas flow
    then most likely it is clogged
    and need to be cleaned or replaced
  5. Oct 5, 2006 #4
    Try the same thing with an LED..a normal lamp has no bias like ray_b mentions above. An LED does, however, and swaping the wires should make it work one way and not the other. Depending on the puls width of the injectors you may be able to see the LED blink, bit I think it's too fast ~5ms depending.
  6. Oct 5, 2006 #5
    thank u all
    dont worry brewnog,i understand how does it work,and i had the same in my mind about what u said about the terminals,thats one is 12v feed from the battery and the other is the injector control(signal from the ecu)
    but ray_b and triden could get what i wanted to know,i thought the lamp i had to turn on had to take two polar terminals,they showed to me that it doesnt need a polar terminals to turn on,im going to use a led,and see,but
    still i question where is the ground terminal?is it the body of the injector?
    and how come the lamp could light without taking a ground terminal?
    and if i used avometer where i have put the avometer terminals to check if the ecu sending the signal to the injector and to know if the injector is feeded by the 12v?i would to put the black wire of the avometer on the ground-right?where should i put?is it the ground of the engine?
    thanks alot again
    for any care to help
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?

Similar Discussions: Electronic fuel injector
  1. Fuel Octane (Replies: 9)

  2. Fuel System (Replies: 16)

  3. Injector Tester (Replies: 4)