Sephakrid

You have an 85, so I'm guessing you have a feedback carburetor? I had a similar issue where the engine would stumble badly unless I floored it. For instance, if I was driving at 30 mph at 30% throttle it would just stumble constantly. However, the truck would still idle normally. The jet on the mixture solenoid was blocked, which caused the truck to run extremely lean. My wild guess is that there's a blockage somewhere in the primary main circuit in your carburetor.

I'm on here all the time, but don't post much because I can usually find answers to my questions by looking through archived posts.

Cameron Knights on Facebook made a 3D printed filter holder! I kinda want one for my truck. https://m.facebook.com/groups/190225185053214/permalink/1831328274276222/?ref=share&mibextid=NOb6eG Edit: He's also got a website. https://www.ck-digi.com/shop/p/nissan-720-cabin-air-filter?fbclid=IwVERTSAPJnO5leHRuA2FlbQIxMABzcnRjBmFwcF9pZAwzNTA2ODU1MzE3MjgAAR4v_o5UmHQzXb9nMWJQjoVeV4tEGOJrR8JWpsGAF2537MG6Lwy-JfZAesltpg_aem_bwjhyoELQ62nLybLnBvAjw

I got around to installing a working ATC on my truck last month and it definitely made warmups on cold mornings (<50F) less annoying. Before, the engine would sometimes sputter and die unless I pumped the gas a couple times pulling away from a stop. Idle was also very rough once the choke was off and before the engine was up to operating temperature. The truck just generally ran like crap on cold days until the engine warmed up. Now it behaves like a typical modern car during warmup. I also noticed that the carburetor base is slightly warm to the touch. Before adding the ATC it would be slightly cool, even after 20 minutes of highway driving. As a sidenote, the Hitachi carb. I rebuilt over the summer is still running great!

Actually, this guide from NICO is pretty helpful, too. https://www.nicoclub.com/archives/nissan-720-pickup-truck-vacuum-hose-routing-and-repair-guide.html

Here are some pictures from my 84 California truck. The U-shaped air cleaner connector goes to the forward port on the carburetor. The other end connects upstream of the two t-connectors. It's part of the line that provides a vacuum signal to the distributor. The large vacuum line that you circled goes from the air cleaner to the top port of the thermal vacuum valve. This line just provides a filtered air source when the thermal vacuum valve is open. The small port on the pipe that comes off the manifold attaches to the ATC on the air cleaner. I disconnected mine because the diaphragm is broken. The clear piece of tubing is just a line that runs to aftermarket vacuum gauge that I installed.

Whoa! Good catch! I've never seen that wiring setup before, although I'm much more familiar with the feedback version of this carburetor with the 6 wire/8 plug harness. That makes finding a replacement idle cut solenoid a little annoying. All the replacements I've seen have the same type of connector crimped onto both wires.

Does the green/white wire connect to the metal box underneath the secondary diaphragm? If so, that's the wire for the throttle valve switch. The switch actuates when the throttle closes, and is adjustable. I agree that it's part of the fuel shut-off system.

All of the Hitachi carburetors I've seen have a glass window to check the fuel level while the repro carbs just have a metal fuel bowl cover with no window. The fuel jets should also be stamped with the Hitachi logo. Offhand, I'd say that your looks like a repro unit, but it's probably still usable!

I found one for a Stanza a while ago. Not totally sure on compatibility but it's the only one I could find anywhere https://www.rockauto.com/en/parts/standard+motor+products,DV25,air+diverter+/+bypass+valve,10192

Yeah, LKQ tries to charge you for every little thing. Last time I got a spare coil for my truck and they charged me separately for the rubber boot that goes over the top! They'll even charge you for light bulbs.

I was able to dig into this over the weekend. Swapped my Hitachi ICM for a cheap aftermarket one (HM703). I ran the same test where I disconnect the forward vacuum switch and observe any changes in ignition timing. Both ICMs do the same thing. The exhaust side coil will shut off (verified with timing light) but ignition will not advance at all. Edit: by "disconnect" I mean removing the vacuum line from the switch so it doesn't receive a vacuum signal.

Well now I'm getting curious. Last year I tested the shutoff system and noticed that while the exhust side plugs will stop firing, the timing will not advance. My truck has an ECU, but I'd guess that the ICM controls timing?

McMaster Carr has a pretty good selection of C-clips. They even have helpful descriptions for what type of C-clip to use for various applications. Measure the diameter and width of the groove with a caliper and order some based off those measurements. Measuring the width of your current C-clip would probably be a good idea, too.

Years ago when I changed the CV axles in my 94 Pathfinder one of the C-clips was too thick to snap over the axle. I went to the dealer and picked up a few different sizes in order to get one that fit. I believe the correct way is to measure axial end play and size up/down until you're within specs but I just installed the thickest one I could and sent it!