Fuel Pump Relays rewire

[Jeepers92]

I'm a bit out of my element now on this 1978 280z s30. 

I believe both of the fuel pump relays are bad. Unfortunately when I ordered the new ones, they don't have the same pin structure so I have to rewire them. I'm simply not sure which wire goes where though I ventured some guesses. 

Could someone take a look at what I've posted in this PDF can correct anything and tell me which wire goes to which? There is a 4 pin and a 5 pin. 

https://www.docdroid.net/4M0eepL/fuel-relays.pdf

Thanks. 

fuel relays.pdf

[Zed Head]

What did you base your guesses on?  The wiring diagram is in the Engine Fuel chapter of the FSM.  There are also test procedures for the relays.  Might be that yours aren't really bad.

Any chance you could post a picture?  Not a fan of clicking strange links.  Never heard of docdroid.

https://www.classiczcars.com/files/category/13-280z/

[Jeepers92]

[Jeepers92]

Worst case is to run a bypass to a toggle in the car to bypass the relay. That seems unsafe because you have to remember to turn it off and I dont know what else the relay controls. However I have to get to work and the shop estimate is well out of range so I have to figure it out myself. I hope I uploaded those correctly. Like I said. Best guesses. 

[Zed Head]

Relays just need straight forward logic.  They can be tedious though, for sure.  Guessing is bad where electricity is concerned.

You didn't say if you confirmed that either of the two relays were bad even though you copied from the test section, so it looks like you've made your decision.  Wire up the new relays and run the tests.  If they pass you guessed correctly.  Good luck. 

[Jeepers92]

I did follow that testing and determined both were bad, The problem i'm having is which wire goes where. Don't know electricity so i'm not sure which wire from the car goes to which on the new relay, the pins are in a different configuration with different numbers. That's the translation I need. 

[SteveJ]

Send me a PM this weekend. I will help you out.

[Patcon]

1 minute ago, SteveJ said:

Send me a PM this weekend. I will help you out.

It sounded like this might be a needed daily driver ASAP

[Zed Head]

The Nissan fuel pump control relay is an odd one, with two solenoid switches in it.  The 5 pin that you showed won't work directly as a replacement, since it only has one solenoid.

If your relays are still installed on the car you might try unplugging your oil pressure switch and turning the key On.  The fuel pump might run then if the oil pressure switch side of the the relay is intact.  The pump will lose power when you turn the key off, so it will only be dangerous in a car accident.  Might get you by.

It seems odd that both relays would be bad, unless the car has been under water.  Any chance that you wrote down the results of your tests?  There might be a simple short term solution based on test results.

The fuel pump relay itself is a common 4 pin relay, easy to replace.

[Jeepers92]

Thanks for the help, I got the relays working as they should, unfortunately didn't fix the issues. 

Anyone know where the ignition relay is on the 78 280z? I pulled the bracket down above the fuse box on the passenger side. None of the numbers on the relay correspond to the ignition relay.  

[Zed Head]

There might be more numbers once you remove it.  Yours looks in great condition though.

 

Here's mine.

[Zed Head]

On 1/14/2019 at 10:30 AM, Jeepers92 said:

I'm a bit out of my element now on this 1978 280z s30. 

I believe both of the fuel pump relays are bad.

Describe the actual problem and somebody can probably get you on the right path.  CO has a 78, I think, and he knows some specific 78 stuff.  He loves looking at those relay diagrams and will explain the fuel pump control scheme in great detail.

And SteveJ and others just generally know Z electrics.  But you gotta give some clues.

Edited January 21, 2019 by Zed Head