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1977 280z no power on fuel pump


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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

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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.

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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.

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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.

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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 by Dave WM
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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

 

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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.

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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.

 

image.png

 

image.png

 

regards

 

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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?

3FC0FA4D-29D3-4EA8-B632-4557A0132836.jpeg

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:

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. 

 

image.png

 

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

image.png

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

 

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@wal280z

 

in term of wires, it’s always setup like this. I forgot if all connection need to connect or not.  But to answer your question, the wire I lift up come from positive terminal with a female out out.  The wire cable come from negative is male connector that connect to a female connector that has black and white wires.

 

It is very likely incorrect connection or one of the wire does not need to connect to anywhere.   If that is the case I must have drop/lost the adapter when I strip down the car.  Otherwise, the possible connection would’ve from the positive, the wire I lift directly connect to negative.  Doesn’t make sense to me.

 

Yes.  The connector you circled.  I found it and it is right near the combine power/fuel relay.

i will check pin 70 again.  Possible reverse power.

 

stay tune

 

regards and thanks for the new wire diagram/schema

 

 

D9A3DB0B-CD4D-4AC6-AE03-3B961515AE1F.jpeg

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Have I gone mad?

pin 70 goes nowhere.  Please see picture.

i decided to disconnect a pair of wire at the battery and only connect the fusible link from positive to the pin 70. But then again, pin 70 goes no where.  Am I reverse connect something?

 

ACA757BC-EAAE-47A8-8F0F-15D14AD0635E.jpeg

4C2ADFE3-A6FB-44D7-AA15-26425D516039.jpeg

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As Captain Obvious, I guess I just have to ask... You sure you don't just have the connectors swapped? Is it even possible. or are they keyed to only fit one way?

I didn't look at any of the wiring diagrams to confirm, but I believe that all the populated locations do something. So just using the populated locations as a guide, I come up with this  :

EFI relay1.jpg

Edited by Captain Obvious
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27 minutes ago, SteveJ said:

I'll just leave this link here for now. I'll look at it more tomorrow and add to the discussion about the pins on the relays. There is some good information here: https://www.ratwell.com/technical/DoubleRelay.html

Well, it took less time than I thought. Line up your connectors this way.

image.png

image.pngFrom the wiring diagram

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I don't recall any problems getting the right plugs on the right terminals on mine.  I think that they are "keyed" somehow.

SteveJ, is that a suitable replacement for the Nissan combined relays?  Is it available?  I think that you were involved in the past in writing up a way to use two Bosch relays to replace the Nissan NLA relay.

Maybe? https://www.amazon.com/Bosch-0-332-514-120-Injection-Combo-Relay/dp/B005JCN1M8

The plugs might not be right but they could be made to fit.

Edited by Zed Head
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5 minutes ago, Zed Head said:

I don't recall any problems getting the right plugs on the right terminals on mine.  I think that they are "keyed" somehow.

SteveJ, is that a suitable replacement for the Nissan combined relays?  Is it available?  I think that you were involved in the past in writing up a way to use two Bosch relays to replace the Nissan NLA relay.

Maybe? https://www.amazon.com/Bosch-0-332-514-120-Injection-Combo-Relay/dp/B005JCN1M8

The plugs might not be right but they could be made to fit.

The original 280Z EFI system was licensed from Bosch. If you look at the link I posted, you'll see that Nissan used many of the same terminal numbers, such as 36 & 39 for the AFM flap. Why re-create relays on a licensed system?

Over at ZCar.com many years ago, there were threads about using the VW EFI relays to replace the NLA Nissan EFI relays.

The "two Bosch relays to replace the Nissan NLA relay" is for the ignition relay. ZCarDepot sells it now. They can beat me on cost, so they can have the business.

I can be pretty sure my answer is correct because @Captain Obvious basically posted the same idea about the connectors. I just put some terminal numbers on mine to line up with the wiring diagram a little better.

 

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Hi all,

There are only 2 possible ways to plug then white and black connectors.  Leaving as is, is one way, the other is swap white with black.  The face of the relay has number on it. Don’t know if you can see it but it is 88d on top left

 

 

 

 

584AAD45-13D8-4F7D-B6A4-529B229A87DA.jpeg

Edited by 240zadmire
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Ladies and gentlemen, please sit down as I'm so ecstatic to share the news.

I swapped the black and white connectors places for the main and fuel relays.  White on left/top and black on the bottom/right.

the kicker here is that common sense, in the USA, we're driving from the right side of the street.  No one need to tell us.  We intuitively just know that without paying any attention.  So, as you've seen my previous posts about battery terminals and everyone is saying fusible link need to be on the positive side.  Long story short, we commonly known that red color represent hot/positive and black is for cold/negative at least for battery.  Guess what, for whatever reason, the previous owner either replace or got a spare one ... and swap it around.  Black is positive and red is negative.  I swapped the black and connects to the positive terminal and the starter and red to the engine block from the negative terminal.  Took 2 cranks and she fires up right away.  Boy, what a sensation I tell you.  Better than a cold beer after working under the sun till your lips crack.  Better !!!!.  I've been working on this for 3 years and I had this car worked before.  It probably too long ago and memory play tricks on me as I'm near the finish line.  Plus the relay is a real killer as well as @Captain Obvious stated, perhaps try swap it and see.  Well, swapping battery terminals and relays did the trick.

 

I'm not out of the wood yet ?

The idle is so violent.  as soon as see starts, she climb to 2500-3000 RPM and fluctuate repeatedly.  Like some one keep pressing/releasing the gas pedal.

Any ideas I should look at is much appreciated.

 

Thanks again for all of you helping me and continue so.  Much appreciated.

 

regards,

 

 

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The red wires at the battery have fooled many people.  Nissan did that, not a previous owner.

I must have looked inside the plug for populated terminals when i was working on my relay.  I thought that they could only plug in one way.  Having two plugs right at the same spot that can be swapped just seems way too illogical, especially for a part that highly engineered and complex.  If I had a car here I'd run out and check, just to be sure it was true.  Seems unbelievable, but, apparently it is so.

Keep going....

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didn't know that is what Nissan did that.  Apologies to previous owner.

did read through the high idle section of the EFI bible.  Follow instruction religiously.  At least turn out the culprit was bad electrical connection at the 3 pins throttle body.  Sand lightly about 30 strokes each pins... last instruction section page 61-68 or so to test voltage when key is in "On" position and notice some pins, the voltage is not the same as battery.  Which lead to some resistant somewhere.  Approximate 11.6 volts instead of 12.34 volts.  Probable cause of this would be the dirty connectors somewhere.  I will trace down later.  When all instructions were completed, fire her up.  Had to crank 3 times and she is up from a cool night.  Pretty happy.  The idle is approximate 2500 RPM or so and slowly drop down to 1500.  Adjust the air intake from throttle body and able to bring her down to 1100 rpm and she is steady.  No flickering on the RPM needle at all.  I couldn't find the needle when using the strobe light.  I must have painted the mark on the pulley.  Will need to get under.

one notice I see is that when rev her up, she is not return to idle immediately.  She hovering around few hundreds where she peaks.  Meaning if I rev her up to 2000rpm and release, she will come down to around 1500rpm or 1700rpm and stay.  If I gently rev her up again and release, she goes down immediately to idle, which is 1100rpm.

 

Just want to repeat my gratitude again for all the helps.  Was beyond my expectations.

any thoughts?

 

regards

 

   

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Is the throttle return spring intact?  They tend to rust and break off.  The throttle body itself has a weak spring but there is an external one also.  You can check if the throttle is sticking by pushing the blade close by hand or lifting the gas pedal with your foot.

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