Zed Head

Unscrew gauge here -

You've found some good correlations but I think that the cause-effect might be off. Closing the AFM vane makes it act like a throttle blade, cutting off air (lowering idle speed), and also causing intake vacuum to increase (causing fuel pressure to decrease). Maybe the vacuum leak guys were right, but your bad fuel pressure gauge is making things confusing. You might have a big vacuum leak, causing low vacuum to the FPR which increases fuel pressure, a bad pressure gauge, causing the fuel pressure look high when it isn't, and and AFM that might be adjusted (except that it appears to be adjusted the opposite way to make things leaner). You have a lot of bad information. Bad in produces bad out. Notice that your fuel pressure reading with no vacuum is now the highest it's ever been. 44 psi. It keeps changing, nobody knows what it really is. If it was mine, I'd get a new gauge first thing. You can unscrew the gauge from the hose, you don't need a whole new setup. Any oil pressure gauge will work also. A 0 - 50 oil pressure gauge will probably screw right on there.

The clear one would work. You could clamp the hose with your clamp and break the connection at the clear connector. The vacuum in the FPR will be released and pressure will rise. The clamp will prevent a vacuum leak at the manifold.

If you cut the line where I marked and have some sort of connector it would work. But the clamp alone won't work because there will be vacuum inside the FPR. You have to release that vacuum. So, you'd clamp the hose, then release the vacuum. That would close the potential vacuum leak, but let the FPR vacuum out. You could also put a T fitting in the cut section and block the third connection.

Reread those posts and the ones right before them. You're back to the same type of situation. The same things apply.

And here...

Let's review...

Enough to be confident that you see or do not see a difference. You're kind of to the point where you should have a better feel for how things work, than you did when you started the thread. Since the engine does run, you can poke around, take measurements, and see what happens. If you just run through the list of things to do your progress will be very slow.

Hose on - pressure reading. Hose off - pressure reading. Repeat a few times. Tell us a story. Your pressure readings are so erratic throughout the thread that you need to do those comparison within seconds and tell what happened.

I wonder if the seals or guides are just too tight. Do you know the type of seal on the valves? Has the head been reworked recently? Do you know the guide material? Bronze shrinks more than steel as it cools. Might be why it happens cold, the guides have tightened up on the valve stems. Should wear in over time, if so.

Get another gauge, even a HF cheapy, or a loaner from OReilly Auto, and confirm the high pressure readings. Stick your finger on the port that the FPR is connected to. You should feel the vacuum. Try another port. There are a couple that are not necessary for the engine. The heater control port, and the charcoal canister purge port, for example. Your collection of things to do is too big, I think, and a bit unfocused. Some of the things suggested to inspect will actually make the engine run lean. Vacuum leaks won't make it run rich. You can see what the AFM vane is doing by watching the counterweight under the black cover. You can also control it by moving that weight while the engine is running. So if you just want to hear it run leaner move the weight more closed. The cover just pries off by hand, there are no clips or fasteners. Just stuff I would do.

I think it was covered a while back, but the FPR vacuum line is connected directly to the intake manifold. If you have brake booster vacuum you should have FPR vacuum. On the other hand there is a ported vacuum line that only gets vacuum when the throttle blade is not on idle, not closed.

Just be sure to separate the two things, in your head. You're planning to look at why pressure isn't reducing from an already too high baseline number.

Pretty sure that you saw a pressure drop with vacuum in your earlier tests. You just have to break this down in to its pieces. The gauge, the FPR, the flow path, blockages, etc. No offense S30Driver, but his baseline setting isn't even right. Vacuum comes next...

There are many possibilities for running rich. The opposite of assuming is confirming. Or pretty close anyway. Assuming is bad, confirming is good.

If you want to try something simple just to see what should happen and make sure you're not losing your mind, take your old FPR and connect it after the fuel filter, dumping in to a container of some kind. You'll need to block one inlet or create a loop, using a T fitting. Put your pressure gauge in between the filter and FPR. Pump > fuel line > filter > gauge > FPR > collection container. Power up the pump and see what you get. Should be 36 - 38 psi. Here's a random thought - is it possible that the outlet on your gauge's "T" fitting is restrictive? Maybe it is restricting flow, causing pressure to rise. Taking the FPR out of the picture, except as a secondary restriction. You might have a measurement problem. Very common, in all engineering endeavors.

Holy moly, why are you reading a newspaper from Dubai? I wonder if a newspaper from one of the richest countries in the world will ask me to disable my adblocker or pay a small subscription fee... It's probably gold leaf.

When you tighten the control arm (AKA transverse link) bolts the inner sleeve of the rubber bushings gets locked. Then when you drop the car the bushing is twisted and holds the car up. You're supposed to have the weight of the car, and two people (nobody does this part), inside before you tighten the bolts. I've thought of this before, but don't think the bushings would take it for long, but a person could "artificially" lower their car, by overloading it then tightening the bolts, if they have stock Nissan rubber.

If you've already done the other hoses and have already installed new injector seals and don't have any leaks, just do it while it's on the engine. The key to making it easy is to get the hose lengths right, not too long, then get the rail ends lubed up (gasoline actually works well) before sliding the hoses on. Slide one short hose length way down as far as it will go, then stick the FPR end in, squeeze the other hose in between the rail and the FPR, then slide everything to the right spots for clamping. Don't forget to put the hose clamps on at the appropriate times. It's a pain to get everything right and realize there's no clamps on the hoses.

Here's some good reading. They don't have an "amp rating", generally. Probably have better luck calculating the max amperage appropriate for the wire gauge. Start from scratch. I just picked these from the internet. Littelfuse and Digikey are well-established names. SAE, of course. Omega has been around forever and used to publish a paper catalog that was basically a primer on all things electronic. https://www.sae.org/publications/technical-papers/content/650122/ https://www.sae.org/search/?qt="fusible%20link"&sort=relevance&sort-dir=desc&display=list&sector=%28"AUTOC"%29 http://media.digikey.com/PDF/Data%20Sheets/Littelfuse%20PDFs/Fusible_Link_FAQ.pdf https://www.digikey.com/ https://www.littelfuse.com/~/media/electronics/product_catalogs/littelfuse_fuseology_selection_guide.pdf.pdf https://www.omega.com/auto/pdf/ref_fusesizingguide.pdf

Fix-a-flat works mostly by gravity, inertia, and air pressure. Might not even get to the bead unless you drive real slow or you get the foamy kind. Make sure it foams, some are just cans of goo.

Good work on resetting the distributor drive shaft to the factory setting. Not sure what's going on with your 123 distributor. Seems like they did not get the drive slot oriented to the rotor in the same way that Nissan did. So the 123 #1 plug terminal is in a different spot. At this point you could probably move the plug wires over one terminal as suggested earlier. To get the timing mark right. You might also need to "phase" the rotor correctly so that you don't get random spark to the other terminal that it's close to, since it's between terminals. As timing advances that problem might show up. Something to do in the future. Does the 123 allow the trigger to be adjusted independently of the drive shaft?

The guys at the tire shops have a container of rubbery sealant that they brush on to any damaged areas of the bead, on either the tire or the rim, before they set the bead. Probably what the "guy" was talking about. Stop by a shop and ask them what it is. Or just have all of your tires removed and reset. If you have steel wheels it might be rust. My spare wheel (funny that we call it a spare tire when it's actually a whole wheel) sat flat with water on it and the bead rusted so badly it was ruined.

That's for the 78 280Z and 280ZX's. One inlet.

If there's a wrecking yard nearby you might check for a 1978 280Z or 280ZX fuel rail and regulator. They will transplant over and it looks like you can get Bosch parts. Edit - the picture they show on Rockauto is wrong but it shows right on Amazon. Cheaper too. https://www.amazon.com/Bosch-64018-Fuel-Pressure-Regulator/dp/B000BZGAOO https://www.rockauto.com/en/catalog/nissan,1980,280zx,2.8l+l6,1209316,fuel+&+air,fuel+injection+pressure+regulator,6124