1978 280Z - Won't restart when hot, all interior gauges, fan motor, backlighting not working

[Zed Head]

1 hour ago, NocturnalEmber said:

The car will crank when warm or hot, it just won't start when hot. The fuel pump activates when the key is turned to start, as does the starter when the spade connector is connected.

I'd diagnose the two issues separately.  There's a crank/no-start issue and the gauge power issue.  You can test the no-start issue by testing for coil power and injector power with the key On and at Start.

It's not clear that the ignition relay is the problem but it could be.  You can test for power with the key on at several points on the path through the gauges and on to the sensors themselves.  I'd start at the fuse box.  If there's power on that fuse with the key On then the ignition relay is fine, for that circuit.

A loose fusible link connection seems like a possibility.  Many ways to break the system down in to parts.

[Zed Head]

5 hours ago, NocturnalEmber said:

**unless a wire is wiggled.** I've traced this down to a red power wire at its connection to the PCB on the headlight switch. Wiggling this wire where it connects to the pcb will make the backlights come on (when the switch is in the position for them to turn on.)

You'll need a meter or test light to continue.  Wiggling wires might get you there but it will be a lot faster with some simple testing equipment.

[siteunseen]

1 hour ago, NocturnalEmber said:

I tested it when I installed the new filter and lines, and I believe it was 36~ when running.

If you try and pinch it it should be really hard to squeeze anywhere past the fuel pump "OUT" side. 30 some odd psi is pretty tight on efi fuel hose from what I've tried to squeeze.

[Captain Obvious]

Here's a sketch I whipped up a while ago showing the functions of the ignition relay. Might help augment what SteveJ already posted.

[Captain Obvious]

Oh... And maybe slow down a little. Focus on one thing at a time.  Pick one problem and get that item working and then move on to the next one. 

It's easy to become overwhelmed and then overwhelm your help. 

[NocturnalEmber]

I really want to extend my appreciation to everyone that has taken time out of their day to upload what they have.  @SteveJ @Zed Head @Captain Obvious @siteunseen @Reptoid Overlords and @Yarb. I apologize if I left anyone out but I think I included everyone. Again, thank you for taking the time you have thus far, it is tremendously appreciated.

My lack of reply for the past few hours was because I was out tinkering with the car. This may change or alter what you all have mentioned previously, so I wanted to report in on this before going further.   I was replacing the thermostat today as part of giving the car a once over, and while I was at it I installed a new coolant temp sensor (the two pin one for the ecu) as I had it on hand anyway and the factory one looked rather jaded.

While I was in there, I double checked my fuel lines for leaks, etc. I went to start the car, and since I had replaced the tank to pump line with more of a correct size that would route through the grommet in the body (3/8"), I thought I should prime the fuel pump and line. I disconnected the spade connector at the starter and gave the key a few turns to try and prime the pump. Well, nothing happened. I heard the relay in the passengers kick panel making a half hearted noise, but no noise from the pump.  At this point I was wondering what could have happened, as the pump is brand new, and it was working last time because I was able to start the car.

I left the key in the ON position, and went looking in the engine bay. I touched one of the fusible links out of pure coincidence, and I hear a clicking in the engine bay and the seatbelt buzzer goes off for a half a second. I spend the next minute or two wiggling the fusible link (I believe if you are facing the engine bay from the passengers side, its the top left fusible link in the top left fusible link box.) Wiggling the links would recreate this clicking noise in the engine bay and the seatbelt buzzer activating for a brief second. 

"Eureka!", I thought to myself, I just accidentally found a lead!  So I get into the car, and turn the key to start, and I hear the pump prime.

So I turn the key a few times to prime the pump to get the fuel line filled with gas, and I look under the car to verify no leaks, and it all looks good.  The only thing that concerned me is the Fram G3 filter isn't completely full, I'll include a photo of it below.  Is it supposed to only be somewhat full like that? Also, will not having the fuel damper right off the pump outlet have any effect on the car? Mine doesn't have it.

 

At this point I reconnected the spade connector going to the starter and tried starting the car. After about ten seconds of cranking it ran, albeit really rough, smoothed out somewhat while continuing to run, for probably a minute or so, maybe more, then it eventually died. So I tried starting it up again, and it fired right up. I tried giving some throttle, and it would only rev a small amount. Even with the throttle wide open.  The tach isn't working so I obviously have no idea what the RPM's were at, but when I'd try to raise the RPM's by applying throttle, it would only rev a slight amount no matter how much throttle I would give it like I mentioned.  

This sounds weird, and I have no idea if this is what is happening or not, but it revved so slow and such a small amount, it seemed like the timing was really retarded (I had an old corolla once that I fully retarded the timing on by twisting the distributor, and it behaved similarly, so it made me think about it.)

Could this be a timing issue? It just seems weird how the car would take ten seconds of cranking to start, then the next time it would start with a flick of the key. 

Thank you again everyone for helping me thus far, I wanted to post this because I wasn't' sure if it would change the direction of troubleshooting people were wanting me to take.

 

 

 

 

 

Edited August 27, 2023 by NocturnalEmber

[SteveJ]

Keep in mind that the tests I listed in my long post will work with the car not running. Do those first. 

Also, post pictures of your fusible links, including clear photos of the bases that hold the links.

[Zed Head]

17 hours ago, SteveJ said:

Test with a voltmeter.

 

10 hours ago, NocturnalEmber said:

I spend the next minute or two wiggling the fusible link

You can't do SteveJ's test with wire wiggling.  Multimeters look complex but most of us only use two of the functions.  Voltage and resistance.  You can ignore all of the rest.

https://www.harborfreight.com/7-function-digital-multimeter-63759.html

https://www.harborfreight.com/612v-circuit-tester-with-5-ft-lead-63603.html

[siteunseen]

My Fram G-3 is full coming straight out of the tank, your's should have a lot more fuel in my opinion. 

You can put a hose on the top side of the metal fuel filter under the hood close to passenger's side of the radiator support. Put the loose end in a gas can but secure it down. The high pressure will push it out of the jug. Unplug the small wire on the starter's solenoid and turn the key to ON. The pump should run without the car engine running. Let it fill up the jug or until the rear G-3 is full and all the air is pushed through the lines. It circulates from the tank to the fuel rail then the excess is sent back to the tank via the return line from the fuel pressure regulator to the tank.

I can't tell looking at the picture if the G-3 is horizontal  from the inlet to outlet but I would want some gravity help keep it full constantly. In other words the outflow to the pump should be on the bottom.

https://www.atlanticz.ca/zclub/techtips/fuel/g3filter/index.htm

Edited August 27, 2023 by siteunseen

[NocturnalEmber]

5 hours ago, SteveJ said:

Keep in mind that the tests I listed in my long post will work with the car not running. Do those first. 

Also, post pictures of your fusible links, including clear photos of the bases that hold the links.

 

Will do! I just wanted to update everyone on that accidental discovery I made last night to make sure that wasn't going to change the direction that was being suggested. I typically keep my multimeter within close reach, so I will get to those tests today and report back!

 

52 minutes ago, Zed Head said:

 

You can't do SteveJ's test with wire wiggling.  Multimeters look complex but most of us only use two of the functions.  Voltage and resistance.  You can ignore all of the rest.

https://www.harborfreight.com/7-function-digital-multimeter-63759.html

https://www.harborfreight.com/612v-circuit-tester-with-5-ft-lead-63603.html

 

 

 

I've got my multi meter and test light handy/within arms reach usually, they're an invaluable part of my toolbox.; The multimeter has came in handy especially when I initially got the car to verify there was voltage at the pump wires before I installed the fuel pump.

 

 

32 minutes ago, siteunseen said:

My Fram G-3 is full coming straight out of the tank, your's should have a lot more fuel in my opinion. 

You can put a hose on the top side of the metal fuel filter under the hood close to passenger's side of the radiator support. Put the loose end in a gas can but secure it down. The high pressure will push it out of the jug. Unplug the small wire on the starter's solenoid and turn the key to ON. The pump should run without the car engine running. Let it fill up the jug or until the rear G-3 is full and all the air is pushed through the lines. It circulates from the tank to the fuel rail then the excess is sent back to the tank via the return line from the fuel pressure regulator to the tank.

I can't tell looking at the picture if the G-3 is horizontal  from the inlet to outlet but I would want some gravity help keep it full constantly. In other words the outflow to the pump should be on the bottom.

https://www.atlanticz.ca/zclub/techtips/fuel/g3filter/index.htm

I only put two gallons of fuel into the tank, so that could have something to do with it, but I figure it should still pull fuel, I'm using the top bung, which I believe is the correct one for feed. It's nearly horizontal, not quite as vertical as the one in the guide, but close.

 

A huge thank you again to everyone! I will report back later today when I have more concrete test results.

[Yarb]

This is not to be insensitive by any means… Are you sure the G3 filter is oriented correctly with the arrow pointing to the pump. It’s easy to get confused when gas is running everywhere.

[Zed Head]

You didn't say if you cleaned and tightened the loose fusible link terminal.  If it responds to a wiggle it's loose.  (All of this wiggling and squeezing is making me feel funny.  Says Garth).  You can just just squeeze them tighter with a pair of pliers.  Don't forget to check the two green EFI links from the battery positive post.  And, of course, check your grounds.