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help with injectors


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Hey guys Im doing an l28e swap into my 71 and im not getting a negative signal to my injectors from my ecu. anyone run into this before? i tested a working ecu out of a friends and that didn't work. im getting 12v to the injectors...?

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Injectors that don't squirt comes up about every week or two. Almost impossible not to find a thread describing solutions if you search "not getting fuel" or "injectors don't fire" or "engine starts then dies", etc.

 

The Engine Fuel section in the 280Z and 280ZX FSMs all give a good description of what causes the injectors to squirt. Easy reading and worth doing at at least once. Not kidding.

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The "signal" to the ECU runs on a wire from the negative post of the coil to Pin #1 at the ECU. Have you measured continuity from the coil to Pin #1? Also, some 280Z ECUs (the ones I've worked with anyway) need to have the the tachometer, with its in-line resistor, installed or the ECU won't work right. I'm not sure how that's handled with the L28E swap. I have an engine on a stand, with 1978 ECU, with the resistor installed, but no tachometer, on a branch off of the line to Pin #1. You might look at that as a possibility, if you're sure that Pin #1 is connected to coil (-).

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My negative on the coil and pin #1 are linked or have continuity. I checked and my tach is plugged in. but im not sure if 71 240z's had resistors ill have to look. Do happen to know where they are located?

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I don't think that the 240s have the resistor since they don't have ECUs or use the same kind of tach. On the 280s the resistor is bundled in to the wiring up by the relays and fuse panel under the glove box. It's a 2.3 kOhm resistor, kind of odd looking with a male and female bullet connector on the same end. Hard plastic rectangular body, about 1 cm x 2 cm (it looks like the drawing in your wiring diagram). If you have the 280Z wiring you might be able to find it and wire it in. Or get one from Radio Shack.

 

Note that I haven't seen a bunch written about this so I could be totally off base. I've had two cars that wouldn't run without it, or the tachometer, installed though, even though the wiring diagram shows the Pin 1 wire as a separate circuit. I'm thinking it might drop the voltage to the ECU or condition the signal so the transistors work right. I'm not an electronics expert, it could be an artifact of two old cars that I had.

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