Captain Obvious

About condensers... Haha! You didn't tell us your points were burned up!!

I know that we've both been there. So are you going to populate the board yourself? I've done a fair share of surface mount assy by hand, but not everyone is comfortable with the geometry. Or maybe... You could tell me that you're gonna toss it onto the pick-n-place at work during lunch break. Wouldn't that be sweet!

That's a long story? Haha!! :laugh:

Lenny, Awesome. Can't wait to see what happens when you get one assembled and powered. I see in the pic you've got the board edge connector installed. Did you harvest that from a stock ECU, or did the part numbers we talked about earlier pan out? I worry sometimes about large low volume parts like that... They say they have stock, but they're in the dark dusty part of the stockroom and they only think they have stock. BTW - Enjoy the smoke from prototype #1! :devious:

Thanks for linking to that doc. I had previously gone poking around the Atlanticz site and found the fuel pump page that linked to the doc you found, but that's where I stopped. That document mirrors my understanding completely (or more accurately, my understanding mirrors that doc, since it was here first!). I was one mouse click away! Lesson? When you don't know, check the Atlantic Z Car Club first, and if you still can't figure it out, then study the FSM.

Cool! Canadian SPAM! Who knew, eh?

Right 78 is different than 75 through 77, but it's not as simple as just the oil pressure switch. The alternator is involved as well.

I agree. With the current system, I think they swung too far in the "unsafe" direction. If my current understanding is correct, once the ignition switch is in ON or START, you could completely disconnect the oil pressure switch and the alternator connector and the fuel pump will run. The sense of the failsafe detection is wrong. OPEN is not failsafe...

Yeah, that's the chart from EF-16. That chart clearly indicates that the intention is that the engine will run with alternator output OR oil pressure. Using the chart you referenced, in conjunction with another chart on page EF-36 and the wiring diagrams, I think I was able to figure out what all of the involved switches and relays do under the different conditions. And you're right... It's a counter-intuitive, convoluted, screwy system. I should really document the system before I forget again.

I don't have a 78, so I can't test it, but if my understanding of the system is correct, the engine should not have shut off. Maybe there was a problem with your alternator, or maybe my understanding of the system is still flawed. I can tell you that the documentation is confusing!

Boy do I understand that!! I looked at a slew of new aftermarket head units for something that I didn't hate and I finally gave up. And you hit on one of the "features" that bugs me. I hate it when you push the volume knob in and it gets you into a menu system. You reach for the volume knob, hit a bump in the road and accidently enter the menu system without even knowing it. Then you crank the knob to change the volume, but change your menu settings instead. Then by the time you figure what's going on, all your settings are screwed up. :ogre: I HATE that! I've got a list of must-haves for my car heat unit, and I think my must-haves rule out every aftermarket unit available. I think I wrote my list down somewhere... If I find it, I'll share and we can talk about it. Here's the basic underlying philosophy from my previous thread about my stereo system: http://www.classiczcars.com/forums/interior-s30/50668-need-help-sound-system.html "Put the stuff I use the most on the left and the stuff I use the least on the right. Don't put all sorts of crap around the volume knob that I'll hit by accident in the dark. Keep it simple."

He's 22? I can do better than that... This should make sense Mang!! Just poking more fun.

Zed Head, I used to think (up until a few days ago) that the fuel pump on the 78 would only run if there were both oil pressure AND a spinning alternator. However, I've now taken a closer look at the design and I no longer believe that to be the case. I now believe, just as you suggested earlier, that the fuel pump on the 78 will run if there is oil pressure OR a spinning alternator. It's really a convoluted screwy system and if I get the chance, I'll put together a description of system operation. But in the meantime, thanks for the help.

I used to think (up until a few days ago) that the fuel pump on the 78 would only run if there were both oil pressure AND a spinning alternator. However, I've now taken a closer look at the design and I no longer believe that to be the case. I now believe that the fuel pump on the 78 will run if there is oil pressure OR a spinning alternator. So your experience above of unplugging the oil pressure sender connector and finding that the fuel pump continues to run makes sense to me. All that said... I still think you should start small and try to figure out which camp you're in... Fuel or spark.

I put a pair of 6x9's in the pressboard right behind the seats so I've got 4 inchers in the side panels like you do and an attempt at more low end with the 6x9s. I'm not happy with the sound of the whole system though and I haven't had the chance to spend any more time on it yet. I know the 4 inchers I currently have in the side panels are crap and they're just in there as placeholders until I get something better, but I also know that my problems run deeper than just those side speakers. Once I get the larger speakers sounding good, I'll spring for better 4 inchers and the ones you put in would be a huge upgrade from what I have in there now.

Cool. Those look nice. Are they the only speakers you're running, or do you have a pair of something larger further back?

I did the same thing about a year ago. Then some time later after I was done, I found that article. Haha! I gotta learn to look first before I reinvent the wheel. I'm not complaining though... My clock works great and I know why. Thanks for the link to that article. I have a copy, but have no idea where I found it.

Excellent! From what you changed, I'm not sure I can pinpoint a smoking gun, but if it stays fixed, the point is moot. Loose or dirty connection somewhere on the low voltage side of the coil? I doubt it was the dirt on the rotor or the posts inside the distributor cap. I don't like the sound of a 40 year old condenser, but I can't come up with a failure mode that wouldn't have had an impact on high RPM's as well. All they can do is leak, go open, or short. Short wouldn't run at all. Open wouldn't have any affect until your points burned up, and leaky would weaken spark at all RPM's not just low. Maybe the rich mixture at low RPMs combine with a weak spark from a leaky condenser? Just looking for a solution that fits the findings...

Awesome. Glad it was a simple fix. I love it when a plan comes together.

Flak? For what? I think your contribution was nothing but valuable. Maybe the forest was missed for the trees... The differences seen between power supplies on the bench and in-car use may not have been voltage at all. It may have been temperature. Warm bench in the shop vs. cold dash in the garage? I will refine the zener regulator voltage though. I've been inside three 77 clocks and they all used 5.1 volt zeners. You should be able to operate the clock down to just barely above that point. I don't know about other years, but I would suspect they used the same value on all of them.

:laugh: Haha! You made me snort! BTW - I'm not denying that this phenomenon exists, I'm just saying that Datsun (tried to) took steps to prevent it. I don't have an explanation as to what is going on, at least not a credible one... My money is currently on Blue's relativity suggestion.

Haha! Combine unusual coincidence with the depth of knowledge and experience here and look what happens! Nice pics by the fire truck. Hope they have a good trip home. They've got quite a drive ahead of them, and I hope they don't have to drive the Z through the snow.

Good. Hopefully they'll see the pics then. I've got more if there's interest. We made contact over at zcar.com, but that forum is pretty hurting at this point. Not to forum bash, but I log in very rarely and might not even know if I've got a private message for six months. If the website even does send out a message, it usually gets hung up in my spam filter. My part of the world isn't nearly as pretty, so I spend more time online. But I spend more time here than Z other forums. I agree... Good people. I was out there on a non-Z related event and was extended a gracious invitation to spend the day at that SCCA event. Mixing Z car stuff with the other non-Z events was a bonus that I really enjoyed. A nice respite from the norm. If they stop over, let them know I was asking for them.

I tried to get pics back to the owner, but they didn't seem to spend a lot of time online and contact was spotty. After being there, I understand though... If I were them, I'd be spending all of my available seconds outdoors as well and not in front of a screen. Do you know if they are members of the forum?

I've got some neat shots of the blue 73 that I took at an SCCA event this past summer. It was a great Z day for me as well! I'm 99.5 percent sure it's the same car/owner. I'll confirm the other 0.5% once you post a pic.