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1983 280zx N/A
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Discussion Starter #1
Hello all!
I am new to the Z world and am almost done rebuilding my '83 zx but have hit a roadblock getting the fuel injectors to work... When I turn the key to run position, I can hear the fuel pump and injector relays buzzing and clicking erratically (honestly sounds like they're speaking Morse code) resulting to the fuel pressure to slowly build and bounce all over the place. There is fuel flowing out of the return hose, and jumping the pump to a constant 12v it works no problem but the injectors don't seem to be firing. I've swapped both relays to no change, checked all the pin connections on the ecm harness based on the fsm pages efec 85 to efec 96 and all looks good except when I probe the efi relay (efec 95) I get approximately 0.01 volts. And the same reading at the relay harness as well. The injectors are getting 12v between the plug and engine ground but I guess no signal to open and close. The only thing I have not inspected was continuity on the fusible links.

I have searched online for answers and scoured the fsm for days but I am running out of ideas. Can someone please point me in a better direction, or at least shine some knowledge on my situation before I pull whats left of my hair out?!?!

Thank you all in advance!
 

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There are 5 fusible links to check. A relay "buzzing" is usually a sign of low voltage to the relay. You need a constant hot feed (from the fusible link) and a "trigger" to activate the relay. Make sure that you have good grounds for the relay circuit and good grounds throughout the harness. I change all the relays and sockets to the modern type of relays-just makes it easier for the owner to replace later on. On the injectors, a "noid light" will tell you if the injectors are activated. You can rent one from any Auto Parts store ( you need Bosch type 2). There is a constant hot to the injectors from the fusible link. The ECU grounds the injectors and, when they open, fuel is injected into the cylinders. I've restored a few 280Z's and 280ZX's and they are a challenge for sure. You can PM me if you need any further help.
 

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1983 280zx N/A
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5 Posts
Discussion Starter #3
Thanks Doug. The buzzing from the relays isn't constant, more random and erratica. I've made my own light from a Christmas tree light and tested the injector plugs earlier... no light but both leads have 12v when grounded to the block. If I probe the brown wire from the injector relay harness I get a constant 12v too. Should I be getting more voltage from the red ecm signal though? I will check fusible links in the morning, do I just probe one lead to a ground or continuity between both ends?
 

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One side of the injector plug should have 12 volts coming from the fusible link- all the injectors are fed from one common source. The other side of the injector plug goes to the ecu. Each injector goes to an individual pin on the ECU-#1 to 101, #2 to 102, etc. The second connected pin on the injector gets a ground signal from the ECU. I check fusible links for continuity. Unplug them and bench test them. Give each one a tug when testing, I've had them look good but be open inside the wire insulation.​

 

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1983 280zx N/A
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5 Posts
Discussion Starter #6
Brand new battery. Im thinking it's a bad ground somewhere. I painted the engine bay when before I put it back in, so I'm hoping that I just didnt clean the body ground connections good enough. I was thinking bad ecm for awhile, but if the ecm has gone bad then I wouldn't even get signal to the relays, right?
 

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1983 280zx N/A
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5 Posts
Discussion Starter #7
Time for an update:
After replacing the ecm, checking all the wiring looms and connections, and lots of head scratching later turns out it was a simple issue I should have caught sooner.. The two grounds on top of the intake manifold were loose. So now I understand why all yall wise Z folk harp on about checking grounds.

But now, my Z runs like a champ!
 
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