SteveJ

I'm glad that resolved your issue.

Thank you for the clear response. The turn signal switch in the 240Z does two things with regard to the rear turn signals. It interrupts the contact between the brake circuit and the rear light you are trying to flash. It establishes contact between the turn signal flasher and the front/rear lights. You can see this in my description for repairing the turn signal switch. https://fiddlingwithzcars.wordpress.com/2012/12/04/turn-signal-repair/

Seeing the 50+ yesterday and having most disappear quickly gives me some idea of the pain you're going through. It's too bad you can't set up some kind of AI to engage and distract the AI bots. Let their bots waste time trying to scam your bots.

A couple of different forums have posts that suggest it's for a knock sensor.

If you want one that works, get ready to pay. Not cheap, but @zclocks stands behind his product. It beats ripping the dash apart to put in a used clock just to find it doesn't work. I did that for someone recently. Buy once, cry once, and do the work once. ZclocksZclocksExpert Zclock repair and restoration

I believe @Mike has been killing off most of them not long after they join, but dang, this board is not his primary job.

Yes, you can pull the transmission without removing the engine. Disconnect the battery negative. Drain the old transmission. Remove the 4 bolts holding the driveshaft to the differential. Remove the driveshaft. Support the transmission. Remove the crossmember. Remove the bell housing bolts. Pull the transmission away from the engine. Drop the transmission down.

Try Junkyard Jenny. https://junkyardjenny.com/

If you're not seeing voltage, it could be any of a number of things including bad technique the contacts within the switch being gummed up the solder pads on the switch losing contact with the switch

This may be about the easiest way to diagnose, but easy is relative. Get some spade terminals like this: https://www.walmart.com/ip/EverStart-Male-Slide-Wire-Connectors-Blue-6-Piece-Model-MDD2-250-16-14AWG/16603216478 Make a short jumper wire with two of those spade terminals. Unplug the turn signal flasher (not the hazard flasher). Plug your jumper wire into the connector where the turn signal flasher was. Take off the clam shell from the steering column. Put the key in ON. Put the turn signal switch on a right turn. If everything is working right, both the front and back right turn signals should be on solid. The same goes for the indicator on the dash. Measure voltage to ground on the top two pins. See the picture below. Your meter should read approximately battery voltage. Report back with the voltage readings you get from each point (note the wire colors, too).

As a matter of fact, there are some idiosyncrasies in the turn signal wiring due to the fact that the brake lights and rear turn signals share bulbs. I lay it out here: https://fiddlingwithzcars.wordpress.com/2013/01/20/hazard-switch-brake-light-turn-signal-circuit-analysis/ While the article focuses on the 72, the same concept is used in all North American 240Zs.

Tuning carburetors - There are videos for that: https://ztherapy.com/videos/ Look for Just SUs and 240Z-280ZX Tune Up. Now, clarify "only creeps regardless of RPM". If the car is creeping along, the RPMs should be low. If the car barely moves and the RPMs are high, that could be the clutch slipping. Either the clutch is worn out and needs to be replaced, or the clutch hydraulics need to be replaced, or both. If the engine bogs down under load, it's a fuel delivery problem. The carburetors could be dirty or not adjusted right. There are plenty of threads on this board about getting Z cars back on the road. Here's one I did on my 73: https://www.classiczcars.com/forums/topic/65643-getting-the-73-back-on-the-road. You can see some of the things I went through with the carburetors and clutch master/slave cylinders.

The hose circled in red is a vent hose for the float bowl. It does not pressurize the float bowl. If the hose is disconnected from the air cleaner, it means you were pulling in some unfiltered air. The hose circled in blue goes down to the exhaust manifold, but it is open to the air, not connected to the manifold. When the flap is in Winter position, it blocks most of the air coming in from the front of the air cleaner, causing more of the air going into the air cleaner to pass over the exhaust manifold. It basically helps with drivability in cold weather. Have you downloaded the factory service manual for your car? They are available on this website in the Resources section. Also you can find owner's manuals here: https://www.xenonzcar.com/s30/ownersmanuals.php Both can help you on your path to get your Z running better.

I drained the old gas out of the 240Z last week. Today, I got back to work on her. First, I installed a new battery. Then, I removed the valve cover and spark plugs so I could put oil in the cylinders and on the cam before turning the engine over. After that, I put a gallon or so of fresh gas in the tank and used a syringe to add gas to the float bowls and to the fuel line between the filter and fuel pump. After a spray of starting fluid to make sure combustion could happen, I tried to start the car. She fired right up and purred like a kitten. I'm looking forward to moving her to my new shop so I can do the rest of the work she needs: new vent hoses, springs & struts, and new rear brakes.

I think he did. https://www.homedepot.com/s/3%20inch%20rubber%20cap?NCNI-5

There is an issue with the VR in the alternator.

No charge indicator light. What is the voltage at the battery when the car is running? I'm wondering if there might be an issue with the internal voltage regulator. Remember that new does not always mean good.

Two wires were tapped: the neutral (yellow) wire between the VR & alternator for the fuel pump relay with the normally open contacts and the black/yellow wire for the starter solenoid was for the fuel pump relay with the normally closed contacts. The tap for the neutral was actually small harness Nissan designed to go between the VR and engine harness. I pulled it out of my 73 a long time ago.

Unfortunately, the 73 wiring diagram won't show it, either. It was added on later. Download this file and look at the mounting points for the relays: https://www.classiczcars.com/files/file/60-fuel-system-modification-plus-73-74/ Also, is the hazard switch a pull switch or a toggle switch. 73 was the only year for the pull switch.

Actually if you suspect an air leak, replacing the rubber lines would be a good start and could alleviate the need for a check valve in the engine bay. If the rubber lines are allowing air in, they can allow fuel out in the future.

I learned from @Captain Obvious that one of the things to consider on a check valve is cracking pressure. Most likely the fuel pump will overcome the cracking pressure on the check valve, but I couldn't find the cracking pressure listed on the Amazon page. For instance, these Evil Energy check valves have the specs listed on the page: https://www.amazon.com/dp/B0FQHSSLN5

That build date would typically indicate a 73, though some states may have titled an 8/72 as a 72 back then. https://jdm-car-parts.com/blogs/news/vin-verification-of-us-datsun-240z-260z-280z-280zx?srsltid=AU7gw4VZKuT31B6faCZYskqAm_f9DiAZx3ONK3Xsnn_scBm8EpKTCGA-

What is the build date of the car? Can you have someone else unplug and plug in the T connector on the alternator while you listen for a relay clicking in the passenger footwell?

I have a habit of researching parts when I hear of people having problems in case I have that problem later or to come up with improvised fixes should original style parts not be available. Recently I was researching vacuum solenoids in case someone with factory AC in a 260Z or 280Z needs replacements. I saw some Infiniti vacuum solenoids that may be adaptable for that.

If you decide you want a new radiator, this one is closer to stock than an aluminum radiator. https://www.rockauto.com/en/moreinfo.php?pk=8609984&cc=1209170&pt=2172&jsn=575