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Hello, I am stumped as to what is going on with my 240sx fuel injector and would like to hear from anyone who has had a similar problem.

The problem started as a fuel flood in cylinder #3, causing a hydro-lock and breaking the starter motor. I have replaced the starter motor and have started looking into the fuel flooding problem. I have replaced all 4 fuel injectors and O-rings and confirmed no leaks.

I have narrowed the problem down to probably the wiring/harness/ecu. With the ignition off and the key removed, injector #3 is still receiving ground signal from the ECU. I took a multi-meter and probed all 4 injector harnesses and this is what I found:

The harnesses have 2 prongs and look like this: ((A) - (B)) Where A is the ground signal sent from the ECU and B is the constant battery voltage.
#1 4.5v A to positive battery terminal
#2 9.4v A to positive battery terminal
#3 11.4v A to positive battery terminal
#4 6.5v A to positive battery terminal
They all have the expected 11.4v measured from B to negative battery terminal.
None have continuity to ground.

So #3 fuel injector is opening 100% anytime the harness is connected. I've confirmed this by attaching the harness with the ignition off and hearing the injector solenoid + watching through the spark plug hole to see the fuel start flooding.

I suspect it is a faulty ECU, sending signal to #3 injector, and possibly weaker signals to #1, #2, #4 but want a second opinion before ordering a new ECU.

Thanks a bunch!!
 
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