cgsheen1

Ah, Layton... I've driven past it hundreds of times... Grew up in Idaho Falls, Mom was from SLC.

What Steve said, and - In both cases the connectors at the sensors are very often the problem. Neither are weather tight and although you don't drive in the rain - and Arizona - oxidation does happen. Sometimes wiggling the two connectors on the fuel level sender helps, sometimes they need to be taken off and cleaned. The posts on the fuel level sender too. You can never be absolutely sure but the connectors under the dash are far better protected than at the sensors so I always start there (sensors) and work toward the gauges checking the wiring. Since your trouble is intermittent, I'd suspect the sensor connectors and/or associated wiring. It's more unlikely but certainly possible: Frayed insulator on wire, to-dash-harness connector, gauge connector, or inside the gauge itself.

The electrical schematic shows that they share a common ground, but I'd expect that to affect your oil pressure gauge too. No step down regulator on a Z car for gauges. There is a fuse in the circuit but there too it would affect the oil pressure gauge and it looks like your hazard switch as well. Check the body harness & engine bay harness-to-dash harness connectors under the glove box. You could test continuity of each of the sensor wires (Y fuel, Y/W coolant). Otherwise you're in the dash to figure that out...

Please NO! For the sake of the next guy that has to remove them! (ask me how I know...) I would also advise AGAINST 3M double stick as well. Instead get just some slim weatherstrip foam from Home Depot or Lowes (closed cell if they have it) and run it around the perimeter or just where you have leaks. It'll squish down to nothing where it needs to and fill the gap where it needs to. And it'll be easy to remove if necessary.

You're not going to like the actual fix: There are adjusters on the back of the gauge for both low and high ends of the needle. Ya, back of the gauge - so getting your fuel gauge to actually represent something close to the amount of fuel in the tank would require removal of the gauge. Then you need to empty the tank and set the "E". Then you have to fill the tank and set the "F". Then you have to reinstall the gauge. In 10-20 years you'll have to do it again because the resistance of your wire and connectors will have changed... And that's why my fuel gauge shows 7/8 full when absolutely brimming with fuel and WAY to the left of "E" when my fuel pump starts sucking air.

TPU is a type of 3D Printer filament. It's flexible. I looked at his photo enlarged and you can see the part has been printed. Lucas, our local mechanical engineer, has a pretty decent 3D printer setup and tried to reproduce the boots for the fuel tank hoses under the hatch in his late 280Z using TPU. Stiffer than rubber. They turned out okay but I wouldn't call them ideal. Might work for the oil cap seal but it doesn't print very smoothly...

So, none of you people live in Arizona?? Our oil cap seals were dried up, hard as a rock, and leaking 30 years ago. I still haven't found a replacement seal that I really like - most work but are a bit too soft. There's always 400 grit and a hard block...

We've seen a couple of those on L engines that have come through the shop. None of them new but they were being used so I assume they worked.

FSM says bullet connector and that's what I use on mine.

Red/Blue (RL) under the dash is generally for lighting (power to bulbs). Hard to tell from that picture but the location is near the center. My 260Z has a RL/B set in that area for the Map Light... However, the 240Z schematic shows a singular RL to the Map Light (must ground - sorry Earth - to the dash frame?). But, it's probably a light for something... It's too short for a center console indicator and the harness ties up tight to the top of the dash frame so stands to reason it's something near the 3 small gauges maybe.

Kk, corrected my post above.

Sorry, I would never put this much effort into making that damn buzzer work. And I do electrical repairs for a living! (Not really for a living, I was being hyperbolic... But I do actually work on a LOT of Z electrical issues...) 🤪

Nope. The Blue for the tach signal comes straight off the "-" coil terminal. If you're still using a single coil, there should be no need to amplify the signal to the tach - even if you switch electronic ignition modules. YOU DO: need to remove the stock electronic ignition module from the system. And, you need to take the tach signal from the coil, not an artificial signal from an ignition module. In my turbo-swapped 260Z I've used many different Ignitors (ignition modules) with the stock coil and the tach worked with them all (because it gets it's signal from the coil connection).

Well, not exactly. You're correct about the early tach being driven by the amperage flowing to the coil. The later tach is "counting" the sparks essentially. It gets it's signal from the "-" side of the coil and it's reading the pulses that are given to the coil by the electronic ignition. The distributor shouldn't impact the tach operation (the wire loop on the back is just reading the coil amp draw like an ammeter). Most of the guys here with 240's have switched to the "matchbox" distributor without issues. You might check the wiring - it's a bit more complicated with the early tach having to run back-and-forth - but I suspect that your tach may just need a good old fashioned ultrasonic cleaning...

The EFI does depend on the coolant temperature sensor for correct fueling. As the coolant temp goes UP, the resistance DROPS. The FSM shows a table for expected temp vs. resistance values in the Engine Fuel section (page 53). Why would you want to ADD resistance to the signal using a variable resistor? Else, why would you remove the coolant temp sensor (thermistor) by replacing it with a manually controlled variable resistor? The aged wire and connectors in your engine harness may already be skewing signal with additional resistance. Additional resistance which would fool the ECU into thinking the engine was running cooler that it actually is. I think a more productive route would be to measure the resistance at the sensor, and then at the ECU - to see how much additional resistance wiring and connectors might be adding. If the skew is significant, a new wire and connector from the sensor to the ECU might beneficial. In my years with this early EFI and ECCS in S30's and S130's, I've found 90% of the problems to be in wiring and connectors. I've always advised: Clean both sides of your connectors, then do it again, Ya... then do it again. and don't forget the ECU... Most people ignore me and just go straight for the AFM. When you know everything there is to know about that Bosch L-Jetronic AFM, go ahead and bust it open. Trouble is, if you did know everything there is to know about that AFM, you'd never actually do that...

As I said in my previous post, the ones I bought and installed are fully dimmable. Ya, bright. Phone video doesn't really do justice. I run them about half speed around town, turn them down when I'm driving in the hills at night... 20230331_192841.mp4

QasimLed Bayonet BA9 BA9S 53 57 1895 64111 T4W Super Stable and Bright Led Bulbs Exterior Marker Indicator Interior Reverse Side Corner Light White 12V DC 10pcs https://a.co/d/9Ah2tn8 I bought the white and kept my green lenses. Mine is an early 260Z and polarity was correct.

So, while I do still recommend cleaning and painting inside the gauges when you have them out, I've gone to the dark side (or probably LIGHT) on the gauge bulbs... After I replaced my H4 bulbs in the headlights with 10K lumen LED's I decided to go LED with everything else in the world - including the gauge bulbs. Yup, much brighter - they work really well with the rheostat so they also dim very well if I want. The LED's in the gauges are still a bit "brassier" than I like (I've been under Thomas Edison incandescent (yellow) bulbs for the first 65 years of my life), They don't annoy me to the point of returning to the little glowing filament. The load is now much less on my turn signal switch as well. Speaking of - I used LED's in the turn signal pilots and now my "blinker" indicators are WAY too bright - especially at night. On the one hand good - cuz I barely hear the tick of the flasher unit in my old age - but on the other hand it hurts my poor old eyes to look at them...

Yes, there's room and flexibility. And in both cases our A/C compressors and associated tubing / hoses are installed. There's a bit of manipulation involved in the liquid line going through the radiator core support to the condenser. It gets pretty tight in that area with the larger AFM and the cold air...

No, this isn't Goldie, it's my son's 280Z. His original color was 304 Gold Metallic. The original color of my 260Z was Brown Metallic which was oversprayed single stage orange... Nick's 280Z had been running with the L28ET for a couple of years when the above pic was taken. I bought the 260 frame in late 2007 and drove it for the first time in March of 2008. Humble beginnings.

I would NEVER delete my A/C compressor! 🤪 It's the first thing I had working after my L28ET was running. But, my early 260Z frame had factory A/C so it wasn't a big deal. (My L28ET was a gift from my youngest son who knew once he gave it to me, I'd have to find an S30 to put it in. He was correct.) Our first turbo swap was into my youngest son's '76 280Z. Mine was done a couple years later. We both used the AFM in the beginning - then a MAF. I'll try to find some pics but all were mounted in or near the usual 280Z AFM location - not USING stock AFM mounts however. I think we cut his out and mine didn't have any mounts to begin with. We did custom cold air from the AFM / MAF in front of radiator core support - not the stock air filter. He still uses the F31 (Infiniti M30) ECU (with Nistune) and MAF. I moved on and will be moving on again to an AEM Infinity 506 ECU. I just need to get the engine harness finished.

Even in an Olde Timey A/C system, there's a sensor attached to the evaporator (cooling) coil and a microswitch or temperature control dial or lever. Just like in your newer automobile... The "knob" came with your new Vintage Air Refrigeration system, correct? You shouldn't need to replace it. You also need to be more specific - "the AC does cut off sometimes." What do you mean? It stops working entirely? The fan doesn't blow? You can tell that the compressor shuts down? Does it start cooling again at some point? To me, it sounds like the charge is not correct - for some people, it's more difficult to properly charge when the ambient temperature is low (like the "winter" months in Arizona when the ambient temps are in the 70's or 80's (but it still gets to 100 inside the car in the parking lot)).

Welcome to the club! Sounds pretty good, I do think that idle is a little high - probably by a couple hundred RPM. The stock L28ET ECCS will "prime" the fuel system running the fuel pump for about 4 seconds at IGN ON. It'll then stop the fuel pump and not run it again until it gets the signal from the CAS that the engine is turning. It doesn't have to be fired, just a stable repeating signal from the CAS. Like I said before, the green LED will come on at IGN ON and will stay lit until the ECU gets that signal from the CAS. You can watch for that too (if your ignition key wasn't on the opposite side.. 😝) Those AFR's look pretty standard for the stock engine management. I'm impressed with your test stand and I think you've got a nice L28ET there. I'm probably more impressed that you have it running so well with the stock harness... Enjoy it! I do. Goldie is an uphill beast - the torque of the turbo motor is awesome even at stock boost. Stock boost is 1/2 Bar (~7ish pounds) and the stock over-pressure relief valve is set for something between 9 and 10 pounds. The intake manifold has a "blowoff valve" built in (that's not what Nissan calls it, but it performs the same function - dissipates the boost pressure if the throttle is suddenly closed so it doesn't slam back to the compressor wheel).

Factory Service Manuals - NICOclub Nicoclub.com is run by a good friend of ours on the other side of town. (the Ads are horrific, but if you need an FSM, it's worth the trip...)

Picture Four: Correct on the three greens to the horn relay. Our left hand drive cars have the horn relay in the same place - it just happens to be drivers side with all the speedo, tach and steering column wiring. We DO NOT have any 4-pin connector on that side that looks like yours (edit: because the US cars didn't have a PASSING RELAY...) End of the dash harness on the left side is just door switch and horn relay. My guess is that it's for the passing relay and the non-US wiring diagram shows similar wire colors. Picture Five: Correct on both. Our turn signal flasher is left side near the steering column, Hazard flasher is right side near the body and engine harness connectors. Picture Seven: I think you need the 1971 FSM Supplement for that. Weird to me that the Body Electrical doesn't show wiring for the Blower Motor or Switch - which that small harness must be. The Heater and Ventilation System is described in the Supplement.