77 280z Injectors not getting power

[Acesss]

Howdy! Recently picked up a 1977 280z, cars getting spark & fuel to the rail but it seems that the injectors arent firing. I’ve pulled them & cranked the car, they will fire at the very last second when turning the ignition off.

 

Brand new fuel pump, & have changed the fuel injection relay out

 

Any ideas? Not sure what to try next

[NewZed]

The computer grounds the injectors every third spark.  It uses the wire to pin 1 to monitor the ignition system.

 

There's a pretty simple electrical system check in the 1980 EFI book.  Check the circuits before getting crazy with parts.  That's why they wrote the books.

 

https://www.classiczcars.com/files/file/32-efi-book-1980/

[Mitchel0407]

The Datsun EFI system might look complicated but once you understand how it works it’s dead simple. Start with the basics and preform all the electrical measurements at the ECU plug. Don’t worry if the measurements are a bit out of spec and try and leave the AFM (Air Flow Meter) alone till you’re out of options.

 

I suspect your issue might come down to something as simple as a bad connection or a broken wire. Try to look for damage to the wiring harness in the engine bay. Even though you replaced the fuel pump measure the fuel pressure just after the filter. The pump might be fine but it could still be that you aren’t building pressure. There is a fuel pump cut off switch inside the AFM to shut off the fuel supply if the engine stops running.