1976 280Z Wont Start

[NicholasKoenig]

Z ran when parked 

Had it running in January after I chased down a misfire issue that came from a faulty ECU. She ran mint so I began my tear down, months later here we are and I thought Id have it running today but no luck. Heres what I got so far from trouble shooting.

My battery is fully charged (tender says 100%), its less than a year old. My digital multimeter has it showing about 12.8 yet when I put the car on the "ON" position, my battery gauge in the dash reads about 8.5. I tested the ECU pins with a dmm and it will read 8 and change. Is this normal? Is this a fault in the voltage regulator? I tested the 6 pin connection that goes into the voltage regulator but didnt have much daylight to really spend time on it. About 3 of the connections read battery voltage, I think 2 read around 4.2 and 1 read really low, I forget the number. 

Fuel pump works when power is applied directly from an outside source (getting proper fuel pressure at my regular and fuel rail gauge when applied) but not from the car itself. The FPR reads 0 and you dont hear any fuel going to the rail. No leaks. Through testing the fuel relay from the ECU pins, I wasnt getting any reading so Im certain the relay is faulty. I bought that today and am just waiting for it. Could this potentially bad relay be causing all these gremlins?

Spark is coming from the coil but no spark at the plugs. Something is up with the dist? 

I checked the AFM through the pins of the ECU harness and that looks perfect. 

Another small thing I noticed, when I hit my horn button, my tachometer will jump!! 

What is going on with my Z? 

Thanks!

[Dave WM]

sounds like bad battery cables. remove and clean the battery post and the cable connector.

[NicholasKoenig]

Just now, Dave WM said:

sounds like bad battery cables. remove and clean the battery post and the cable connector.

The battery post was clean and the connection is brand new. I must have taken them on and off about four times today. 

[Dave WM]

how do the headlights look? nice and bright? horn sound strong? heater fan? just stuff that pulls a lot of current.

check the fuse link for corrosion (the one that connect the battery to the ECU).

Edited August 21, 2017 by Dave WM

[NicholasKoenig]

Just now, Dave WM said:

how do the headlights look? nice and bright?

check the fuse link for corrosion (the one that connect the battery to the ECU).

Headlights (and fenders) are off the car at the moment. Fusible links are all brand new so I didnt think to check them today. Assuming the links connection is solid what would be the next step?

Once Im back at the car I could plug in the headlight. Assuming its dim, what then? 

Thanks

 

 

[Dave WM]

talking about the fuse links that connects from the battery post directly to the ECU.

If the headlights are dim and all the rest of the stuff like horn starter etc.. all exhibit low volt behavior, then I would suspect the battery, regardless of what the voltage tender says. You need to check the internal resistance of the battery, correct voltage means nothing CCA is what matters.

 

[Dave WM]

oh and I assume you have checked for good grounds, chassis ground from neg term to battery post, good neg connection to starter, good body grounds everywhere else, like the one under the fuse link boxes etc....

[NicholasKoenig]

Just now, Dave WM said:

oh and I assume you have checked for good grounds, chassis ground from neg term to battery post, good neg connection to starter, good body grounds everywhere else, like the one under the fuse link boxes etc....

I did clean the ones I could find but I will go back and check the grounds again. 

As for the battery, I put the key on and crank, the motor turns and turns (no fuel and no spark after the coil now) but will read 8volts and less when cranking. Maybe you are right and the CCA are diminished. I believe autozone will check batteries for free and that should determine if its a keeper or not. 

I wont be able to do much work on the Z for the next few days so Im trying to get the trouble shooting out of the way and jump right in.

If you have any other advice please feel free, Im all ears. 

[NicholasKoenig]

Current solutions aside, this doesnt sound like a voltage regulator issue?

They are fairly cheap but would have to wait probably a week ish until it arrives so ideally Id order it now. But at the same time Id rather not "throw parts" at it.

[Dave WM]

could be but that can be tested after you get it started (voltage reg) no need to order it, you maybe able to just clean up the points on the old on IF its a problem. If you charged the battery with a charger and its weak now, the I would suspect the battery.

IF after you get it started and IF the battery voltage is not being maintained by the alter then

 

Edited August 21, 2017 by Dave WM

[NicholasKoenig]

8 minutes ago, Dave WM said:

could be but that can be tested after you get it started (voltage reg) no need to order it, you maybe able to just clean up the points on the old on IF its a problem. If you charged the battery with a charger and its weak now, the I would suspect the battery.

https://www.youtube.com/watch?v=9qeYW_Rnoo4

I watched the video and realized Im already subscribed to your channel!!

I did actually open my voltage regulator up and the alignment looked good at a glance but tbh I didnt know what I was looking at lol. Mine looks slightly different that the one you showed in the video but Im sure the same applies. I did hit it with some crc electrical connection cleaner but will try the 1000grit like you mentioned. 
 

[Dave WM]

8 minutes ago, NicholasKoenig said:

I watched the video and realized Im already subscribed to your channel!!

I did actually open my voltage regulator up and the alignment looked good at a glance but tbh I didnt know what I was looking at lol. Mine looks slightly different that the one you showed in the video but Im sure the same applies. I did hit it with some crc electrical connection cleaner but will try the 1000grit like you mentioned. 
 

only IF you need to. you need to get the car running with a good battery and then test the alt for output.

if there is no or low output it could be a VR issue or an alternator issue. Too soon to go down that rabbit hole, you need to get the car started and the alternator turning before do any checks.

Edited August 21, 2017 by Dave WM