L28 Going in to the 240z - Missing Under Dash Parts

[SunnyZ]

Hi there,

I was referred here for answers from another forum. 

I purchased almost everything out of the engine bay of a 1976 280z with fuel injection. I see there are 4 plugs and 2 white wires before the firewall grommet. Research shows that 2 of them are for the Main relay and Fuel Pump Relay. Can these be replaced with an off the shelf relays?

And yes I looked at the FSM, admittingly I'm pretty horrible at wiring diagrams. Any help would be appreciated. 

[SteveJ]

Holy crap! Now the Bosch relay is out of stock everywhere!

[Zed Head]

Here's an old thread that talks about replacements.  Big picture though, you could just use the wiring diagram and power things up to get the EFI system working.  The combined relay is more complex than it needs to be.  In 1978 they split the two relays apart.  Were it mine, I'd power up the EFI system using the 1978 diagram, and use more modern methods for the fuel pump, like an inertia switch system.  Or, just use 1978 relays and a 1978 wiring diagram.

The two white wires in your picture are for diagnostics.  You can ignore them.  #1 is probably the ground wire.

 

[Zed Head]

The Factory Service Manual has the pinouts and the connector shapes shown in the various chapters and the wiring diagram.  For #4.  

https://www.classiczcars.com/files/

[Zed Head]

#4 might do fuel pump stuff.  #1 might actually be the trigger wire for the ECU from the coil negative.  By the diagram and the connector shapes.

[SunnyZ]

Wow, that would have been a great replacement. Now going for $380 on ebay for the Bosh relay!

 

Any idea how 1 connects to the coil negative?

To confirm that relay would be for plugs 2 and 3?

4 is for fuel pump stuff? ie? There is a datsun junkyard a couple of hours from me and might be able to pull them. 

@Zed Head which chapter or page is that diagram from? I will attempt to trace it back. 

 

Thanks for all the quick answers!

Edited July 6, 2023 by SunnyZ

[Zed Head]

 

[Terrapin Z]

I have a used OEM relay. I never tested it. 

[SunnyZ]

Thank you, I'll let you know if end up needing it.