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I have a 300zx with a potential stuck open fuel injector and it is dumping fuel out the tail pipe. I started my diagnosis at a random fuel injector connector. I unplugged the connector and front probed it with my testlight attached to ground to find the control wire but both sides of the connector is showing me battery positive and the wiring diagram is showing me the Red wires are all battery feed but I don't under stand how my control wire is showing me battery feed anyone have any ideas?
To make sure I understand: With the injector disconnected and a test-light connected to battery negative, front probing the control wire lights the test-light? Is this the case with ALL injectors, or just one?
Disconnect the harness from the ECM. Does the the control wire still show battery voltage?
"Knowledge is a weapon. Arm yourself, well, before going to do battle."
"Understanding a question is half an answer." I have learned more by being wrong, than I have by being right.
This is 100% normal on an older style bank fired injection system. Because injectors share a control signal from.the PCN the voltage is back feeding through the companion injector(s) the voltage will disappear if all the companion injectors are disconnected.
This chapter 13 material in Paul's book.
Link to section in Paul's in SD Premium
A bank fired system is the fuel system equivalent of a wasted spark ignition system. All the control sides of the injectors in each bank are all connected to one control signal from the ECU. It was only when emmisions and fuel economy standards were tighten up that fully sequential fuel was introduced and each injector was controlled individually.
" We're trying to plug a hole in the universe, what are you doing ?. "
(Walter Bishop Fringe TV show)
the weird thing is when I looked up the diagram the battery voltage wire splits and feeds into each injector and each injector has it's own individual wire that feeds back into the ECM instead of 3 to 1 wire feeding back to the PCM which would tell me it was a group fired injection.
I see the wiring diagram too and each injector has individual control wire. But it has to be wrong. Do you hear other injectors firing like in the video? Do what Andy wrote and unplug the other injectors, then you'll know.
The commonn connection easily be internal to the ECU, it is impossible to second guess why manufacturers design things a certain way, this applies equally to both electrical and mechainical.
" We're trying to plug a hole in the universe, what are you doing ?. "
(Walter Bishop Fringe TV show)
I see the wiring diagram too and each injector has individual control wire. But it has to be wrong. Do you hear other injectors firing like in the video? Do what Andy wrote and unplug the other injectors, then you'll know.
Likely to be wrong. The only way it would have sequential firing of the injectors if it used an infiniti M30 ECU of a similar year. The Z31 ECU only has two injector drivers.
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