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Traced it down to the injectors!!


joker120

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As you all know I was having quite a time with the damn harness on my 78. The injectores are firing, it's in time and I have spark...

 

Now the question, Is there a small cap on the end of these injectors that has some function? Mine have deteriorated and the injector will deliver fuel when the needle houseing is depressed and the engine will fire when I throw gas into the head so any idea guys? Is it these simple caps?

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You must be talking about the pintle caps. The general word seems to be that they don't significantly affect anything if broken. Broken caps certainly wouldn't keep the injectors from injecting.

 

If the injectors have fuel pressure and they are energizing then fuel has to enter the head. Are you sure that the injectors are firing? People have been known to remove them, attach them to the fuel rail and place them in to containers, then crank the engine to verify fuel flow. It takes some work but if the engine runs with fuel added through a vacuum port or the throttle body then lack of fuel through the injectors is the obvious place to look.

 

You can also turn the key to On, connect a jumper wire to the coil (-) and tap it to ground to hear the injectors fire. Credit to Tony D for describing the method, the basics of why are described in the FSM. Basically you're telling the ECU that the coil has fired three times and the engine has made one revolution. I just tried it to be sure it works. Three sharp taps to ground and you can hear the injector solenoids. I have a 76 but the electronics are essentially the same as your 78. The wire from coil (-) to the ECU Pin 1 runs through the tach by the way. So the 280Zs won't run without the tach installed.

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You must be talking about the pintle caps. The general word seems to be that they don't significantly affect anything if broken. Broken caps certainly wouldn't keep the injectors from injecting.

 

If the injectors have fuel pressure and they are energizing then fuel has to enter the head. Are you sure that the injectors are firing? People have been known to remove them, attach them to the fuel rail and place them in to containers, then crank the engine to verify fuel flow. It takes some work but if the engine runs with fuel added through a vacuum port or the throttle body then lack of fuel through the injectors is the obvious place to look.

 

You can also turn the key to On, connect a jumper wire to the coil (-) and tap it to ground to hear the injectors fire. Credit to Tony D for describing the method, the basics of why are described in the FSM. Basically you're telling the ECU that the coil has fired three times and the engine has made one revolution. I just tried it to be sure it works. Three sharp taps to ground and you can hear the injector solenoids. I have a 76 but the electronics are essentially the same as your 78. The wire from coil (-) to the ECU Pin 1 runs through the tach by the way. So the 280Zs won't run without the tach installed.

 

this is what I've done so far, pulled the rail and injectors but they have power and just arent pulsing open best I figure....

 

I was going to jump off the + of the battery since it's right there unless the current isn't stepped down before the injectors...

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No problem bud. Not sure what you mean by "under there" though.

 

Make sure that your injectors are actually opening when the engine is turning over. Good luck.

 

The jumbled mess down there refers to this rail and injectors that are kinda a pain to get at lmao

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The injectors are opened by the ECU grounding the circuit to energize the injector solenoids. The injectors will always have power when the key is at On or Start. If you have power at the injectors then you need to look at the grounding circuit.

 

The ECU gets it signal from a wire that runs from coil (-), through the tachometer and to Pin 1 at the ECU. Check continuity from coil (-) to Pin 1 at the ECU plug. The tachometer needs to be installed for your car to run.

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Funny thing is I hear the injectors cyclIng

 

You can hear them when the engine is turning over when you try to start it? They only cycle once per each engine revolution when the engine is turning over and the coil is firing. You might be hearing rocker/valve noise, it would be hard to distinguish injectors from all of the other noise with the starter engaged. Try grounding the coil (-) with the key On. The only noise then will be the snap of the spark when you tap to ground and the injectors all energizing every third tap. Or the screwdriver from injector to ear method while cranking the engine.

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