SteveJ

@Reptoid Overlords is probably thinking there is a constriction somewhere, either in or out, that is limiting the engine speed. That is what I was angling for, too, but starting with fuel. The fouled plugs indicate rich conditions unless the rings are so bad on each piston that you're getting oil into all of them. Too much fuel would overwhelm the spark, but I would expect the engine to die at that point. What I was asking you to do in my previous post was to see if you could correlate fuel pressure to engine performance. Since you don't have the fuel pressure gauge installed, all of this can only be speculation. Data is more important. I was suggesting 500 RPM increments only because it would be easier to differentiate monitoring points. Ideally, you would make a video with a tachometer (from a timing light or multimeter) and fuel pressure gauge in the same shot, then we could correlate the engine sound, engine speed and fuel pressure. (A video done correctly can be very helpful for remote diagnostics. I knew I had an exhaust leak in my 240Z, and I sent a video slowly moving across the engine while the car idling to a friend. He said the leak was around #2, and he was right.) So could there be a restriction in the intake? That is worth examining. Is the flap moving cleanly and easily, or is it getting hung? Is there something in the airbox or between the airbox and AFM (think critter houses) that could be blocking air flow? Could the exhaust be blocked? Again, I would expect the engine to choke and die, but I could be wrong. I have seen several videos online of mechanics shaking a squirrel's stash out of a muffler. Lastly, as I said before, make sure all of the wires on the coil, distributor cap, and plugs are fully seated on the components, especially the coil to cap wire. A weak spark could account for poor performance. Since this thread is already 13 pages, would you please state again the age of the coil, cap, rotor, and wires? Are you on the stock ignition, or do you have a ZX distributor or other ignition?

First, establish the baseline on your fuel pressure. Measure it at idle, and then step through the engine speed at around 500 RPM increments, noting the fuel pressure. See if it starts to tail off. If it does not, then it could be spark. If the plugs are black, why? Is the fuel pressure too high? Is oil getting past the oil control rings? Is the exhaust visible? Is there a lot of soot on the inside of the tail pipe? Is your spark that weak? Do you smell gas in your oil? Pull your dipstick and sniff. Be sure to double check that the plug wires are firmly attached to the coil, distributor cap, and plugs, per my previous post. What fuel pump did you install? What is the flow rate?

If you're worried about the contact, you could remove the heat shrink and stock terminals, and crimp the new terminals like these: https://www.ebay.com/itm/314175912098 on with heat shrink. I have to admit that I haven't been following the rest of this thread much. There are too many rabbit holes. For hot restart, look at what can be affected by heat: Fuel rail. Test by parking with the hood open. If the problem goes away, then you could be boiling your fuel. I would install a fuel pressure gauge to verify. If the fuel pressure goes down (FPR leaking down), the chances of boiling the fuel goes up. TIU. Test by having a can of dusting air. If the problem happens, hold the can upside down and spray the TIU. If the problem resolves, replace the TIU. This also applies to the matchbox if you have done the 280ZX distributor swap. ECU. I think I saw someone suggested percussive maintenance. If the problem goes away after you rap on the ECU a couple of times, replace the ECU. I am not sure what you mean about not being able to rev about 20%. If the car won't take load, that's usually a fuel problem. (I looked back on the thread, if the car can't maintain speed, it's likely a fuel problem.) It can be a spark problem if you have a weak spark on 1 or more cylinders. A friend couldn't figure out why his 240Z wouldn't go above 3000 RPM under load. He didn't have an obvious misfire problem, either. He's a very good Z wrench, but he was too close to the problem so he couldn't see the forest for the trees. I started working from the coil down to the plugs. Once I got to the distributor, I pulled off each plug wire, one by one. On #2, the plug wire was not fully seated into the cap, though the insulating boot was firmly over the cap. I got the wire seated against the metal, and the problem went away. Without load, the weak spark wasn't manifesting itself. However, under load, the weak spark from the extra gap caused poor combustion in #2, and the car was running on 5 cylinders. I have a short form video on Youtube at myZcarlife about that.

OEM - https://www.nissanpartsdeal.com/parts/nissan-fusible-link~24161-28500.html

A friend was working on a customer's 78, and there was an issue with the headlights. I took a quick look at it a couple of weeks ago when my friend was hosting a party (It was a great way to decrease the amount I had to socialize.), and it seemed like corrosion in the fusible link may have been the cause. The fusible links were pretty nasty. My friend put in a Maxi Fuse holder, but the problem remained. I went out to take another look today. I saw voltage on both sides of the right fuse when I pulled the ground on the circuit. However, the was no voltage on the downstream side when I had the ground plugged in. I cleaned the fuse holders with a wire wheel, but no change. Neither headlight would light, either. I swapped the fuse for the right headlight with another that was in the fuse box, but that fuse wasn't in great shape. I got another 10A fuse from my friend, and a little while later, I detected that it had blown. Getting nowhere fast in my diagnostics, I talked with @Captain Obvious, but I couldn't provide enough information for a true ah-ha moment. He did make a good suggestion to start using a test light instead of a meter because we both knew I had to get around an impedance issue if it existed. I decided to focus on the left headlight next. I disconnected the headlight and rigged up a jumper between the engine harness connector and the headlight connector. I rigged up another jumper that I could connect to ground. I still couldn't get the left headlight to light up with the new ground. I checked things with the test light. I could get the positive side of the wiring to light up the test light, but the ground leg would not cause the test light to light up. (Hold on to this.) At that point, my friend and I broke for lunch, and I discussed the next steps with him. We agreed that pulling off the headlights would be the course of action because I narrowed down the problem to that part of the circuit. He got the front end on jackstands, and I got the left headlight out. This is what I found. Yikes! Someone thought duct tape would make good insulation. You can see how hot and melty it got. That is the positive wire with all of the missing insulation. Unfortunately I didn't have my headlight connectors with me to replace the bad terminal. At least I found the impedance issue with the left headlight. I'm surprised it didn't pop the fuse. I went over to the other side and pulled the right headlight. I found someone had overfilled it because all of the excess water came out. Okay, so the outer sheath had cracked and without inner liners, water got trapped inside the sheath. I cleaned it up and wrapped it with electrical tape. I decided to put in a 15A fuse since my friend had those on hand and test just the right headlight with the left disconnected. Sure enough, it lit up nicely. I'm not sure what caused the 10A fuses to pop, but I'm going to install a 10A fuse when I go back next week. With the right side operating, I connected the left headlight bulb (H4 housings with halogen bulbs) to the socket and turned on the headlights. The right still came on fine, and the left was dim. I'm thinking the left side was probably getting its power from the right side fuse backfeeding it. Next week I'll return to my friend's place to fix the wiring on the left headlight bucket, and he can have the owner pick up the car. Lessons learned: Follow my own advice and ALWAYS remove the fuse to test it. I was fooling myself early on when I didn't test the fuse for continuity. I know that the headlights can back feed. With a car that you're not familiar with, you don't know what someone might have crossed wiring-wise. (Finding a wire nut in the engine bay is also a BAD SIGN.) Have plenty of the right size fuses on hand when doing the testing. A fuse kit will become a regular part of my road kit for house calls. I keep them in my Z cars, but it wouldn't hurt to have a third for my tool kit. Drill down to the component level to verify diagnostics when you don't have a smoking gun. I spent more time at the entire circuit level than I should have.

There was an error in my list. I can't remember when I found out. This one should work better: Amber 1157 LED (front turn signals) https://www.amazon.com/gp/product/B08CZ1GRJY

It matches what Rockauto lists.

That's exactly why I was looking at the compressor and mounting bracket from Nostalgic AC. It mounts on the other side of the block.

Keep in mind that I didn't say I was able to do it successfully. When I encountered that, the owner's son worked at a Kia dealership, and he had one of the mechanics in the service department tear out the non-functioning AC system. It might be that the system will need to be drained of refrigerant if it's still functional, get the hoses off the compressor, and replace everything after you fix the fuel pump.

You'll have to work the compressor loose and pray there is enough flex in the AC lines.

You'll have to hold his beer.

You gotta love the double-fisted engine starting fluid technique.

If it's a Nissan regulator it is adjustable. If it's aftermarket, who knows?

Just keep in mind, @the_tool_man, if you go with the Frontier alternator, choose from the offerings under New.

I would advise against it. If the voltage spikes more, you could take out your ECU.

Your car has a voltage regulator. I can see the plug. Frankly I don't trust reman alternators anymore. I have been advising people with bad alternators or regulators to do the Nissan Frontier swap. RockAuto lists "new" alternators for the 2000 Frontier 4 cylinder. You have to buy the plug for the sense and switched circuits. That is readily available on Amazon. I also went the extra step to buy the 6 pin Yazaki YPC male plug to make the jumper to remove the voltage regulator. I haven't had someone come back to me about the RA alternators I suggest failing.

High voltage is usually one of two things. The voltage regulator is failing. The battery sense voltage isn't present. Basically, pull off the connector for the voltage regulator. Measure voltage to ground on the white/red wire on the engine harness side of the connector. It should be battery voltage. That wire comes off the black fusible link, so likely it is the voltage regulator.

Brake fluid resistant o rings: https://satoriseal.com/epdm-o-rings/ Possible source: https://www.globaloring.com/product-category/o-rings-standard-sizes/epdm-o-rings-70-duro/ Also Grainger: https://www.grainger.com/category/hardware/o-rings-and-o-ring-kits/o-rings?attrs=O-Ring+Material|EPDM&filters=attrs&gucid=N:N:PS:Paid:GGL:CSM-2296:9JMEDM:20500731&gclid=Cj0KCQjwmvSoBhDOARIsAK6aV7hsgn4gz-ujED1fAZtebKNIUrXo8v9nFtvHkkFkzsinR_BlCy2wcGcaArBbEALw_wcB&gclsrc=aw.ds ebay: https://www.ebay.com/itm/191606666667?chn=ps&mkevt=1&mkcid=28&srsltid=AfmBOor_yVAmh3TJG4uEj6AhV9ox_DipN4S0kR0MRQJokpwBeTghkeCWF7A&com_cvv=d30042528f072ba8a22b19c81250437cd47a2f30330f0ed03551c4efdaf3409e Finally McMaster-Carr: https://www.mcmaster.com/products/o-rings/

I'm glad you found your answer. I looked a little online and through a couple of service manuals yesterday. I had some understanding of how it was supposed to work, but I think the drawing you just posted explains it better than I could have. Most of the drawings I found didn't show the heater strip clearly like that one does.

Actually 12.8 is an acceptable voltage.

The discussion of the fuel pump probably deserves its own thread, but I'll go ahead and give my 2¢. Measure the pressure in the fuel rail before you do anything else. It should not be more than 4 PSI. If you removed the mechanical pump, then you can measure pressure at the entrance of the fuel rail. Otherwise measure the pressure between the rail and one of the carburetors. There is no fuel pressure regulator. There is only an decreased orifice at the exit of the fuel rail. If your pump outputs more than about 7 PSI, you will have too much pressure in the fuel rail. (Note: Most of the PSI ratings for the small fuel pumps are exaggerated.) If you are buying a new pump, then electric is probably the way to go. I have seen too much online (and heard from amongst Z friends) about new mechanical pumps not performing. If you are determined to replace your electric fuel pump, consider a model like a Carter P4070 (https://www.amazon.com/Carter-P4070-Line-Electric-Fuel/dp/B000CIQ5DG). Keep in mind that any replacement fuel pump will require some routing of fuel lines. I also suggest considering a couple of lengths of Sidewinder fuel hose in the right diameter (https://www.amazon.com/16-Universal-Molded-Fuel-Line/dp/B07G2ZWGRG). This helps prevent kinking hoses. I used some on a friend's car, and it looked like it really belonged in the car. I like having an inertia switch in the fuel pump circuit, too. It can be one salvaged from a wrecked car or a new generic one from Amazon. They can cut the fuel in an accident even if the driver is incapacitated.

That certainly explains the ammeter reading. The reading in your latest photo seems to show the fuel pump draw if the battery was fully charged given how you say everything is wired. What is the voltage reading with the battery topped off and car running?

Good thinking. I tried finding a grommet, but all my grommets were too thick. I used a small slice of 1/2 inch heat shrink, and that held the bulb socket in place better.

Yeah, run a test with you holding the positive meter lead firmly on the battery post while the car is running and warmed up. If the voltage is below 13.5, reach across and operate the throttle slowly while looking at the meter. See if the voltage will hover more in the 14 volt range. Please trace out that red wire. I'm wondering whether someone "fixed" the wiring in the past or just added things.