Zed Head

More resistance will give more fuel. Most of the potentiometers available will give way more resistance than needed, enough to flood the engine out. The engine probably wouldn't even run if you had the knob turned to full rich. So whichever end of the rotation it's at now is going to be the lean end.

I might be wrong here, with the electrical terminology, but I think that it depends on which side of the potentiometer you are using as a rheostat. If you wire up one side, it will be clockwise, the other it will be counterclockwise. Only two of the three pins are used. So yours could be either way, if you didn't measure resistance before you installed, you'll just have to turn it and use your nose, or the seat of your pants. Actually, I see that it's referred to in the atlanticz.ca page that you linked, about 1/3 down. I don't think it's necessary to short two pins together as shown, but apparently it won't hurt anything.

Any chance the head had some warpage? Was it machined to flatness before building, or maybe at the high end of the warp limits and used as-is? I've never rebuilt an engine but I'm curious. I have a warped head in the garage and wonder how much is too much and what the effects are.

You said in Post #14 that you charged the battery, the lights came on, and the starter was clicking like mad. You can still do the voltage drop test at the battery posts. If you aren't even getting a glimmer from a light, then the voltage should drop to about zero when you turn the key, if you have a bad battery that won't push amps.

There are some diagnostics you could do to separate battery from connections. Put a voltmeter on the battery posts, not the ends of the cables but the posts themselves, then turn the key to Start. If it's a bad connection, you'll get the click and the lights dimming but very little voltage drop because very little current is flowing. If you get a big voltage drop directly from the posts, then you have a bad battery or a very high load (low resistance or partial short) somewhere else. Could be the starter, for example. You can also measure resistance from the post to the connector (wire end) and from one connector to another. It should be essentially zero. Any resistance will heat up when current flows, expand and get more resistive. A couple of really simple things you can do before you spend more money.

I think that you missed the point that John Coffey was making in Post #2. 240SX's didn't come with turbos or CLSD's. But 85 or 86 200SX's might have. Look for 85/86 200SX Turbo parts.

FastWoman wrote up a procedure for rebuilding the fan clutch. It's out there somewhere. Involves replacing the silicone fluid inside, apparently it gets gummed up and stops flowing correctly. Wouldn't be surprised if there was something on atlanticz.ca also, although I haven't checked.

If your lights came back and the the starter got back up to click level, I would go back to Post #2. Check the connection between the wire end and the clamp also, odds are you have aftermarket clamps on corroded wire ends.

That is the first verified account I've read of a chain actually jumping a tooth (or two). It gets proposed all the time but I've never seen it verified that it actually happened. Thanks for the story. You probably saved the owner the cost of new pistons from the slippage happening at high RPM. He owes you.

I use the tiny little port that supplies the AC reservoir (the white bottle on the passenger side). Removing the FPR hose will change your fuel pressure and your air/fuel mixture, changing the way the engine runs (richer). I wouldn't use that one.

I only suggested the head gasket because some of the signs fit, but the signs also fit some of the other suggestions, like a collapsing hose, along with an ignition problem, for example. Those pressure numbers sure don't look good though. You have so many cars, and you're building your own engines, so I'm sure you know how to get good test numbers. Since it's so new and has few miles, I wonder if re-torquing the head bolts could save it? Not likely, but a re-torque would tell you if any of the bolts were loose, before you removed them to work on the gasket. If you find loose bolts, at least you'll have a possibility for the cause.

Instead of obvious, scary might be more appropriate. Headgasket,maybe? New engine, cylinder misfire and overheating.

The coil, both sides, should always measure battery voltage with the key on. Voltage drop happens when current flows, when the volts are used to do work (resistance is work). The ballast resistor is designed to drop the voltage to the coil when the engine is running, but it's bypassed when the starter is used to counteract the voltage drop from the starter motor. If you're measuring 9 volts with just the key on you have a short somewhere, because no work should be happening, since the coil circuit should be open. When the engine is running, there is current flow through the coil as the circuit is closed and opened to create spark. In short, after my rambling, your ignitor might be bad, apparently the early ones do that, shorting the coil to ground all the time. If you disconnect it from the negative post of the coil, you'll probably see 12 volts at both sides.

Either your battery is dead or you have a big draw at the point that you're measuring voltage. With the key on, and the engine not running, you should measure battery voltage at the coil. Voltage won't drop unless current is flowing, which it should not be doing with the engine not running. Dead battery seems most likely here. What is its voltage, measured at the battery terminals?

So, on the fuel, it sounds like the filter was blocking gravity flow of fuel to the pump, and the pump was so dry it's rotors were just spinning in air. Interesting fix. You should still check pressure before messing with the AFM. Fuel pressure is the basis of fuel injection. You can waste tons of time if your fuel pressure is not right. There's a whole chapter specific to the automatic transmission in the FSM. It's the only chapter with color in the diagrams. Also has a very large trouble-shooting chart (not a good sign!) with "failure to shift 1st to 2nd" as one "trouble".

I don't know what the L28's use in "tasmaina" (OP's location) but big cams on a stock EFI system is bad, big cams on carbs is good. That's what I've learned anyway.

Auto stores can check both separately if you take them in.

The flickering sounds like my Pathfinder alt before it died. But you have an external regulator on yours. You might just need a new regulator, your alternator might be fine. And your stock 73 alternator should be either 50 or 60 amps, by the FSM specs. If you already have a 60 amp, then switching to internally regulated won't get you much, if all you need is a regulator. Not positive, but I think a bad regulator can drain your battery also.

Well, maybe they swapped the other ends of the wires, for those minor changes that CO mentioned. Weird, maybe the PO was saving some money. If you go back to the 280Z ECU, you want A11-600-000. But you'll want to check the pinout of your harness before using it. On the fuel pressure, I had a fuel pump on a test stand that spun up fine to proper pressure initially but slowly stopped spinning as it warmed up. You might put a voltmeter on the pump leads and see if you're losing power or if it's just a bad pump or if you have a clog in the fuel tank. Or disconnect the small starter wire, turn the key to Start, and let the pump run while listening.

Look in the Engine Mechanical and Engine Tuneup chapters of the 73 FSM, at the various drawings. You'll see the pipe that should be in that hole and a hose that attaches to it. Since you don't have PCV, the hose is probably attached to the air filter housing. It's called a breather. Normally that liquid would just drain back in to the engine, and vapors would get sucked in to the intake system.

1977 doesn't have the O2 sensor (they came in 79, I believe), so the 810 ECU will always be open loop unless someone modified your exhaust system. Captain Zero's point about the pinout is good, I'd be surprised that it plugs in. The FSM says Do Not plug old in to new or vice versa. Maybe they swapped harnesses also. Or maybe you have a Maxima L24 engine in your 280Z. If you have an L28, another thing to consider would be that the full fuel enrichment curve of the ECU is designed for a smaller engine. I think that above a certain AFM vane position, the fuel enrichment is delivered off of an RPM-based map built in to the ECU. You'd probably be lean at full throttle. But this wouldn't explain your fuel pressure dropping. Sounds like you're AFM fuel pump contact switch might be tripping. Could be a vacuum leak or just an idle that's too low.

John C's suggestion was a good one. Timesert addresses the concern of inserting too deeply. Link below. Going one size up means one odd bolt to worry about forever in the future. ++ TIME-SERT Threaded inserts for stripped threads, threaded inserts, thread repair stripped sparkplug's, Ford sparkplug blowouts, threaded inserts threaded, repair stripped threads, stripped threads, inserts threaded inserts, Ford spark plug repair,

Just noticed that my comment was assuming that the red circle, the PCV pipe, was the "hole" in question. Looking at his first picture though, I don't recognize that one, which seems to be the one he's referring to. It's so close I can't tell what it is. Also, it looks like he's running carbs on an L28. So the PCV system will be different. The P might not be there, it might just be a V.

Use the 1972 FSM here to get started. Best to confirm a problem before assuming and replacing. The act of replacing will probably break more things. Small jobs become big jobs. Index of /FSM

Just reporting a before and after (the hole), and a back to before. The heat was real, and of large quantity. Posting for anyone who might have a similar issue. No issue, no reason to do anything. For the record, my 1976 car is lowered about an inch and missing its splash pan. Maybe that affects air flow through the tunnel. For those who like a puzzle.