NewZed

You could just unbolt the other side, where the nuts are undamaged, and see what's there. Or, isn't the bolt head visible under the u-joint? The snap-in ones don't have a bolt head there. Or you could probably file or grind that damaged portion of the nut off. Some alternative thoughts.

1975 comes with a 60 amp alternator and an external voltage regulator. The main thing you get with the ZX alternator would be to save money on buying voltage regulators. I don't think that a ZX alternator would be 50 amps either. I think that Datsun went to 60 amps at the 260Z and stayed there for quite a while. You probably have an old external Z alternator. Are you sure it's the alt and not the reg?

In general, the O2 sensor gives information back the computer that is used to lean out or richen the mixture, mostly for cruise conditions. Otherwise I believe the computers use an internal map that assumes a certain injector rate, and uses temperature and air mass to determine how long to hold the injectors open. You have bigger injectors so unless you've retuned the computer (maybe that's what modified means?), it is using the map for small ones, probably adding much more fuel than needed. That's all I know, just a few things in general. You have a mix of parts, the more information you give, the better the advice back you'll get. I'm interested, I've seen a few examples of the 300ZX ECM modification but not a lot of detail on how to make it work well. I think if you search "afshin" and "300ZX" you'll get some threads to look at. I'll bow out now, there's others here who know more.

This observation may or may not help - your first paragraph shows that you are way ahead of where many people are when installing Megasquirt for the first time. Which makes the second paragraph about connecting four wires for power kind of confusing. How could you do the first but not get the second? Just my initial thought the first time I read your post and when I just read it again. The second issue with getting some responses is that your pictures are enormous! I think that they are the largest I have ever seen on this forum. I have 2.5 Mbps upload speed which is middle of the road for internet and it took ~10 seconds to load the pictures. Then they were way too big to look at, I could only see one corner. Many people probably bailed out or thought that their computer was locked up. If you can still modify, I would shrink those pictures down. Back to the problem, I have found that this link has some good basic advice for wiring - http://www.megamanual.com/mtabcon.htm#wire'>http://www.megamanual.com/mtabcon.htm#wire Here is the same page from the top - http://www.megamanual.com/mtabcon.htm

Are you using the stock 1983 ECCS with a working O2 sensor?

You need to post a picture. Just because we want to see it.

List the 5 choices.

Sorry about that, you are right, I don't know the 240Z. I was responding to the misdirected answer and I over-answered. philipl wants to know if his wires will overheat if he has 60 amps available instead of 40. The answer is "only if you add more loads." Swapping a fast-blow fuse for a slow-blow link will just make the system more sensitive, but won't affect wire heating for normal conditions.

So, in theory, you could draw up to 80 amps through the harness from the starter lug back through the wiring harness, which was designed for 40 amps. You've removed all of the individual circuit safeties, like the headlights fusible link, and combined them all in to one 80 amp fuse. You haven't made anything safer, you've just made it more likely that you'll melt a wire before the big new fuse blows. If you added enough new loads on the harness, you could possibly melt some wires, especially if you have a short in a wire. The alternator will only put out the amps that the various loads combined sum up to. How did you calculate that the 80 amp fuse would fail before anything else?

This thread is worth reading. Lots of good insight on wiring and the ammeter. http://forums.hybridz.org/index.php/topic/96568-alternator-question/

The 76 does have a VR sensor system. If it's a Federal model it will actually have two VR sensors (pickup coils) on the breaker plate. One for warmed up normal driving, one that advances the timing when the engine is cold.

Regarding engineering decisions in the 70s and 80s - don't forget emissions requirements. They weren't designing engines just to run cooler or make more power. They were designing engines that would meet emissions standards. Retarded timing, EGR systems, etc. They might have been designing them to run hot to get a cleaner exhaust. Just offering something to consider when trying to figure out why things were changed. Their objectives were different.

If you go through this page, using your browser to search for "VR" you'll find several options. http://www.megamanual.com/v22manual/mwire.htm#ignition The two wires inside the distributor are your positive and negative leads to the variable reluctor. There's a drawing on page EL-27 of the FSM - pickup coil assembly. I am fairly sure that you could run a circuit in parallel to trigger Megasquirt, while leaving your ignition module wiring alone. But I could be wrong. The reluctor voltage ranges from very low to very high though so you might have the same problems with its signal as you're having with the coil negative. It is susceptible to noise also. You're just trading one voltage signal for another. The coil output trigger should be easier. Full disclosure - I don't have Megasquirt but I do like to get into these problems so I'll know it better later, if I ever get my own. These are just places to look.

Your 77 distributor already has a magnetic pickup, or variable reluctor (VR) sensor. You should be able to run the MSD setup using the output from the VR. As long as the pieces inside the distributor are still there and work correctly.

The switches just complete a circuit when they are in use. Connect an ohm-meter to each switch, the one that completes the circuit when the transmission is in reverse is your reverse switch. It's a good idea to do this anyway to make sure the wires aren't broken (looks like you have one broken already) and the switch moves far enough to complete the circuit. I think that you're right on the other two, neutral and top gear. The same method applies.

I have spent some time in the past trying to figure out why my Aeromotive FPR leaked down quickly and eventually came across some information on the internet from an Aeromotive person, acknowledging that they leak down rapidly. I would guess they're saving money on machining costs. I didn't understand the OP's first post either, in light of what was found in the end. Probably too many things going on at once, with new parts and all. Edit - mr jdm beat me. I think that most FPRs will hold pressure. You're right jdm, the Aeromotive's work fine when the pump's on, but most OEM FPRs will hold pressure for weeks or months. Edit #2 - the comments I saw from Aeromotive were similar to those in your second link mr jdm.

Bummer that you spent all that time only to find that the Aeromotive FPRs leak down quickly (edit - couldn't find the document to back this comment up)). If you look back at your original problem description, and the followups, it doesn't quite fit what you found. Just sayin', there's something odd. I think that most people set fuel pressure with the fuel pump running. You can also set fuel pressure with the engine running also. Disconnect the vacuum hose to the FPR, set the pressure with the engine running, then reconnect the hose. For future reference, easier than rigging something up to keep the pump running without the engine running. It's all fun though. Good luck with the rest. Edit - just saw RTz's post. The Aeromotive FPRs use a steel ball on an aluminum seat for the valve. It doesn't seal tightly, but it does regulate well. (or this one either).

Longer studs are tempting, considering how hard it is to start the nuts on my current wheels. What does the back look like, where the stud heads seat? It looks like the spline counts are different. Did you just pull them through anyway?

I don't have Megasquirt but I've been reading up on it. You said that you've been reading posts but have you been reading the installation manuals? Granted, there's a ton of info out there that's difficult to wade through, here's some suggestions. These might have what you need - http://www.megamanual.com/v22manual/mwire.htm#safety http://www.megamanual.com/v22manual/mwire.htm#idle These might be helpful - http://www.megamanual.com/mtabcon.htm#22 http://www.megamanual.com/mtabcon.htm#22 http://www.diyautotune.com/tech_articles/megasquirt_install_writeups.htm http://www.diyautotune.com/tech_articles/tech_articles.htm http://www.diyautotune.com/msmoreinfo.htm

There are conflicting facts in your thread. Earlier you said that 12 volts direct would not make the pump turn, which pointed to a bad pump at the least. Now the pump turns (maybe, at least it makes noise) but fuel doesn't flow? I would start at the basics. Take the pump off and see if gas comes out of the tank, to confirm the inlet line is not clogged. Connect 12 volts to the pump and see if it turns. Hook up some hoses and see if the pump pumps with 12 volts (water or gasoline if you're careful with sparks). Prop the AFM flap open with the key On and measure voltage at the pump wires on the car. Etc. Somewhere along the way there will be a failure. Edit - the fact that it didn't turn the first time you connected 12 volts but you hear some noise now points to a worn out or rust-clogged pump, not an electrical issue.

Have you checked power on the wires? Battery voltage at B+ and Coil - with the key On? Broken parts could cause no spark. I've seen the magnet under the stator broken. There is a set of tests you can run in the Engine Electrical section of the FSM.

Does the L28 use an electric fuel pump (the PO would have had to install a mechanical otherwise). Your fuel pressure could be too high.

Actually, no injector firing could be from a bad ignition module. The ECU fires the injectors when it gets the signal from the negative post of the coil. The sudden death then miracle revival sounds like ignition module also. There is a one or two wire (green) in-line (separate from the ones under the covers) fusible link for the EFI harness. If you short your harness now, you'll burn up all the wire to the point of the short. Edit - the "spirited run" is a clue also. High rpm heat up the module causing it to fail. Cooling down revives it.

I would read this thread before doing too much else - http://forums.hybridz.org/index.php/topic/95316-braaps-l6-efi-induction-advice-and-tips/ 56 psi with bigger injectors doesn't fit. That would give a LOT more fuel over stock since the ECU just controls open time of the injectors. Double whammy on fuel enrichment. ~ 36 psi is the stock setting with stock injectors. Your AFM has a screw for adjusting idle air volume, to lean out or richen the idle mixture. It's on the side under a rubber plug. And the ECU adds fuel when the TPS is at the idle setting. Idle mixture is essentially separate from everything else, so probably shouldn't be used for tuning for driving.

I had considered doing something similar to my car when I was having problems adjusting the fuel pump contact switch in the AFM, which is what your car came with also. At times, the fuel pump would get turned off at low RPM. Enough air was getting by the AFM vane to let the contact switch open. In your case, a PO might have either jumped the AFM switch wires (maybe at the relay) or bent the switch in the AFM so that it's closed all the time. You might trace out the AFM switch wires and see if you can get back to stock. If you take the cover off of the AFM you'll see the small contact switch and how it works. Where was that switch installed? Did you lose your oil pressure gauge readings? Edit - or if you want to keep the oil pressure switch, get one from a 1978 (maybe later also) 280Z engine. Datsun went to the oil pressure switch and alternator current safety system in 1978. The 78 switch has the oil pressure sensor also but I think that you would need to wire it differently that what you want to replace. Second edit - I'm not sure the 78 switch would work since it uses a different relay. By the wiring, it looks like the oil switch just completes a path to ground. But it might be worth a look.