1977 280z no power on fuel pump

[Zed Head]

We're contradicting each other here.  Oh well.  It all depends on what your end goal is.  Everyone has their own way of doing things.

Having the engine running will keep the battery charged. 

[240zadmire]

I'm an engineer myself too.  Not mechanical or electrical so I know exactly what you meant by "written" by engineer instead of tech writer ...  I will follow both your suggestions of troubleshooting and find issue.  Meanwhile, I'll hot wire the pump to see if the pump actually deliver fuel to the injector without cranking the engine up.

stay tune.  Learn a lot actually.

 

regards

[Dave WM]

21 minutes ago, Zed Head said:

We're contradicting each other here.  Oh well.  It all depends on what your end goal is.  Everyone has their own way of doing things.

Having the engine running will keep the battery charged. 

yea its really just preference, pump needs to work properly so I like to focus on that 1st.

[Zed Head]

24 minutes ago, 240zadmire said:

I'm an engineer myself too.  Not mechanical or electrical so I know exactly what you meant by "written" by engineer instead of tech writer ... 

I didn't mean that in a bad way.  Dave WM and SteveJ are both engineers.  And, actually, if I had your problems I probably would go through all of the tests shown in the FSM, and probably take the top off of the relays to examine the coils.  If I had the time and the work space.  I've already done that once with a combined relay and had a switch jumpered on to my working relay in the car so that I could run the pump with a switch or run it normally or turn it off completely for theft prevention.

I was just offering the shorter path.

[SteveJ]

Thank you for posting the photo of the EFI fusible link. Did you check to see if you had 12 VDC at pin 70 of the EFI relay?

If you do, then I would focus on the ECU and why it's not providing the ground at the EFI relay.

[Zed Head]

Just for easy reference. 

 

Edited August 5, 2020 by Zed Head

[Dave WM]

No engineer here, bean counter, but I did room with one at FTU (now UCF) I think I was accepted into the engineer club when I was able to quote star trek during summer reruns (and I knew the resistor color code, that was unexpected). We had 4 engineers and one accountant in the dorm suite.

Edited August 5, 2020 by Dave WM

[240zadmire]

if you address to me offended by "written" by engineer? no sir. I'm thick skin!  Shameless some might say ;).  Isn't all engineers are like that?

The pin 70 R/W is 11.4V.   Battery is 12.3V.   Some resistance somewhere? 

 

regards

 

[Dave WM]

 

typical resistance losses, but you should check in under load. For test like this I like a test lamp.

Edited August 5, 2020 by Dave WM

[Zed Head]

One easy thing you can do is to apply power to pin 74 at the relay plug.  You can jump wires right at the plug to do this.  This will test the wiring all the way back to the pump.  If you apply power to pin 74 but the pump doesn't run then nothing you do at the relay will help.  Run the power through a light or a fuse in case the circuit it shorted.

I like to break the big circuits in to small pieces.  There is a plug beside the passenger seat that the pump power runs through.  You can also apply power there is you get nothing at pin 74.

[240zadmire]

Hi all,

 

connect pin 70 directly to green/blue wire at the rear of passenger seat and leave the black wire intact, the pump spins.

reconnect green/blue wire to its rightful place.  Run power to pin 74 produce a small spark.  I know, I was impatient to buy a test bulb/pen.

Definitely a short circuit somewhere.

traced the pin 74 leads to a connector of 6 pins with only 5 wires.  It ultimately ends at wire connect to the pump at the rear of the passenger.

I tried to see where is that mysterious 6 pins, 5 wires at the fuse box area on the passenger and could not find it.   It has to be somewhere.  

 

the analog voltmeter is really handy.  Must get one.

 

 

 

regards

 

[wal280z]

7 hours ago, 240zadmire said:

Hi all,

 

The micro switch on the steering column on the signal side? Is it the one where my finger point to it or the plastic where 3 wires coming in/out? And the fusible link for the ignition at the positive terminal?

The wire that you are lifting - is that from the negative or positive battery lead?

The fusible link (in your picture) appears to be connected to the opposite terminal that you are lifting.

The EFI fusible link is a black fusible link with a white nylon 'crd' to tether the connectors together in case the link fries.

 

7 hours ago, 240zadmire said:

i do have the FSM and the schematic from https://www.atlanticz.ca/zclub/techtips/wiringdiagrams/F77ZCAR-WIRING1.pdf.

Do yourself a favor and delete that copy from your computer, and download the latest revision from the download section of this forum.

44 minutes ago, 240zadmire said:

traced the pin 74 leads to a connector of 6 pins with only 5 wires.  It ultimately ends at wire connect to the pump at the rear of the passenger.

I tried to see where is that mysterious 6 pins, 5 wires at the fuse box area on the passenger and could not find it.   It has to be somewhere. 

 

 

Are you referring to the 6 pin connector circled on the attached screenshot?

If so, it's not by the fuse box.