Zed Head

For ignition purpose alone, "sequential" and wasted spark are the same, except that the spark jumps backward for three of the plugs with wasted spark. For ignition spark is always sequential. Sequential is a word used to describe injection, when the cylinders only get fuel on their compression stroke. And sequential is really only effective at low RPM, and it's really mainly for emissions purposes. Just wanted to put that out there. Injection and ignition are two separate events. Even when people go to something like Megasquirt, they can do it in two parts, completely independently. Either one can go first. And ignition timing is always done from the crankshaft because timing is based on piston position.

The AFM plug has been known to fall off. Check that. Really need more detail though. Is the engine fully warmed up or cold? Has it ever run right? I know you've posted before but I can't remember the details. Add a a lot more detail. There's almost nothing in this post.

https://www.thezstore.com/page/TZS/PROD/11-2997

It doesn't. You can download a service manual from the site's downloads area. Read the EFEC chapter, it describes the EFI system. The Electrical chapter describes the ignition system.

True. He could modify his also, I'd guess. It's the clamping screw that's the issue. Keeping the ZX distributor is the easiest. It's not connected the to the EFI system. You can keep it and run carbs. I was responding to the question as asked.

https://www.autosportlabs.com/the-new-megajolte-mk2-is-here/ https://trigger-wheels.com/store/contents/en-uk/p72.html https://www.mgexp.com/article/mgb-edis-installation.html

You're combining injection control with ignition control in your post. That is full "engine management". More than the topic. Patcon was right, Megajolt is a basic ignition control system. The other advantage is programmable ignition curves. Optimizing for power and efficiency.

The MSD 6AL is a "high energy" ignition system. Your setup looks right, as-is. The 75-77 280Z's ran a smaller gap than the 78 280Z's because they did not have the high energy system yet.

https://www.oreillyauto.com/shop/b/ignition---tune-up-16776/distributor-12503/8c7c95368caf/1972/nissan/240z?q=distributor

Get a 240Z distributor. It will drop right in. You'll just need to identify the correct wires to make it work but they are all there.

I wrote something about this earlier but erased it. But now that I've thought about it more it might actually be a possibility. Rotor phasing. The lower initial timing might cause the rotor to spark on the terminal before or after the proper terminal. Rotor phasing is weird because the the mechanical advance moves the shaft in relation to the pickup coil. But the rotor is on top of the shaft so its phasing moves also. centrifugal advance moves the phasing, vacuum advance does not because it moves the breaker plate. I could probably work it out in my head but it's already taken some effort just to pull that out. I remember spending some time trying to get the burn pattern more centered on my rotor back when i was messing with timing and high energy ignition. It was hard to get more than hall of the rotor terminal burned though. Not the center just one half of one side. If less than one half of your rotor terminal shows a burn mark the phasing might be off and its sparking to the wrong terminal. A thought.

New thought. Turning the distributor body to change timing is disrupting the ground. The ignition module grounds through the body of the distributor. Usually there's an extra wire to the body also, to assure good ground. Check your ground, I'd say. It's critical for ignition module performance.

This is the weird part. Edit - never mind my last post. My logic only works if the 10 degree is better than the 15. More advance is different. Edit - so with the extra 5 degrees the spark would happen earlier in the rotation.

"coil pack" usually refers to wasted spark. Coil on plug is COP. Both require their own ignition or engine management system. Hybridz.org hs a few examples. madkaw made his own trigger system. He has studied the situation. @madkaw https://forums.hybridz.org/forum/94-engine-components/ https://forums.hybridz.org/forum/93-megasquirt/

You need to verify that the pressure actually dropped first, right? The gauges are very old. Not going to last forever. And the sensors are known to fail. Seems like, no offense, you're forging ahead based on a tenuous assumption. Potential for much wasted time and effort. Unless, of course, you're just a little bit bored.

Not an uncommon topic - https://www.classiczcars.com/forums/topic/62563-lightening-of-the-flywheel/

You can get BSP to NPT adapters from McMaster Carr. Can't remember the exact size I think I've posted about it before. I wouldn't trust the dash gauge. https://www.mcmaster.com/standard-pipe-fittings

When you're working with these EFI systems you really need to make a list of things to check and follow it, unless you have a really good memory. Make a list then run through it, check, check, check.... Otherwise things will look like just a bunch of random actions and results.

Patcon seems on target for the most likely cause. It is actually relatively easy to verify both cam and ignition timing. Forget about all of the tricks and part orientations for a moment and just think about "when" things are supposed to happen, The basics of how an engine works. Think that way for a while then go to the engine and put the #1 cylinder where it should be for its first firing, see where the camshaft position is (both cam lobes and the notch and groove), and look at what the points are doing and which spark plug wire is about to get a spark from the rotor. Spark happens when the points open. You'll need to know which way the distributor rotates. Set everything up so that the points are about to open for #1 compression stroke at about 10 degrees before TDC and the engine will be ready to start. No offense intended to anyone but we all can think in different ways. The "what is supposed to happen" method, imagining parts in motion, works best for me, maybe it will help here.

The new FPR will probably not fix your running problem. The engine will just start and die more quickly. Just trying to be clear....

He's reaching 36 psi. The pump and regulator seem to be fine. Leakdown happens when the pump is not running, it's a starting problem. I think that we might be getting our diagnostic methods mixed together here.

Yes, that's how the system works. Fuel passes through the regulator back to the tank after 36 psi is reached. The fact that it leaks down after the engine dies might affect starting time but won't affect how it runs once it starts. You have a running problem not a starting problem.

Yes, the switch and sensor are combined in one unit. Just pop off the plug at the round sensor/switch on the side of the engine block.. Turn the key on and the pump should start running. It's a good test of the fuel pump control system.

Sounds like it's starting on cold start valve gas, but the injectors aren't opening to keep it running. Might also be the oil pressure switch or alternator. Try removing the oil pump sensor connector. This will cause the fuel pump to run when the key is on so watch your cans. The pummp will stay on so you'll know if it's a supply problem or something else. How long does it run for during each start attempt?

What year is it? Not all 280Z's are the same. You might do better to start your own thread instead of piggybacking on old ones.