Paulytunes

This is mine (build date of 7/76): One forward plug and one aft plug.

Thanks, I'll look into that. So should that vacuum house then be open to the air or connect to something else that I am not seeing? There's a three way tee, which was always connected to the dashpot nipple, a vacuum port on the bottom of the AFM, and also to the charcoal canister vent on the other side of the engine bay. The dashpot connection does indeed seem to be common, many other L28 engine photos online show it connected.

So after much trial, error, troubleshooting, and going through the Fuel Injection Bible and FSM, I was able to get my 280Z running again. The issues I have now: I stupidly broke the plastic nipple on the stall dashpot while connecting the thermostat sensors and wiring: Idling is pretty high, around 2000rpm at cold start. Occasionally, it will adjust down to 700 to 800 rpm and will sometimes stall. Other times it will stay at 2000 rpm, unless I drive it and can force the RPMs lower with the gearing. When I take it out of gear, it shoots right back up to 2000 rpm. May be due to the temps here, which were between 55 and 60 degrees F today. I was able to temporarily fix the dashpot and reconnect the vacuum hose to it using a smaller diameter tube to insert into the part of the intact plastic and the vacuum hose until I can source a new dashpot assembly. I'll continue to diagnose the high idling and see if this is due to something I am overlooking or a symptom of my rebuilt ECU not performing up to OEM standards.

Zed Head - that is Interesting, thanks for finding that site. The OP never does say what he did with the ECU.

Thanks! This was certainly an unexpected and unfortunate discovery. I wasn't able to track down how to troubleshoot the ECU - those pages are probably long gone or that institutional knowledge died when the company went 6 feet under. I have had nothing but trouble with aftermarket parts that one of the PO's installed - first the fuel pump now this. I guess I am at a crossroads - Do I try to source a working 1976 Datsun 280Z ECU, go down the Resto mod path of installing a FAST ECU or other replacement system, or continue to struggle and troubleshoot with what I have (even though it may be an exercise in futility)?

So as I continue to troubleshoot, I pulled out the ecu to inspect it. When I unscrewed it and examined it, I noticed a qr code. When I scanned it, I am sent to a website that no longer exists. The website was Installapart.com. It appears that Installapart is no longer in business. Were they a rebuilder of ecus? Why did they go out of business? Has anyone here ever heard of Installapart or used their ecu services?

I decided to go back to the beginning of the 1976 FSM (Page EF-21) and attempted to diagnose why the engine cranks but won't start. It listed the AFM test first, so I went ahead and did that. I skipped over the fuel pump (since I recently replaced it), and then moved to the water temperature sensor test. I checked the connections at the AFM and Water Temp Sensor, both were snug. Bullet connections are snug too. I'm at a loss as to why I am not getting any continuity unless I am either doing the test wrong or I managed to really fry the wiring after I accidently and inadvertently wet the connections and burned up the fusible links.

Update: so I tested the temperature transmitter. It has the appropriate resistance for the coolant temperature. However, when I test the connection pins at the wiring harness, I get zero continuity. This is for pins 6 and 8, 7 and 8, 8 and 9, and pin 13 and ground. This leads me to believe that maybe the wiring harness is possibly bad. Could I have ruined the whole harness when I unintentionally gave the lower thermostat housing wiring connections a coolant shower and blew out my fusible links? If so, I feel like an idiot and that one's partially on me. Also partially on whichever previous owner decided to over bore the thermostat bolt, and Nissan for using non-waterproof electrical connections under a gasketed connections for coolant. 🤦‍♂️

Thanks! I will test the resistance at the ECU next. I'll be looking for a higher resistance reading since it is starting to get cooler here and my garage is not insulated.

That's what I was afraid of - the Fast EFI almost looks too good to be true. I also really don't want to stray too far away from stock if I can help it.

So I was running fine through most of the summer, until mid-August when one of the connections to the water temperature sensors broke while I was on my way to support a Cub Scouts event and show the kids my 280Z. Since I was going to be sidelined for awhile waiting for the new switch to arrive from Z Car Depot, I decided now would be a good time to flush out the coolant, replace the thermostat, etc. No good deed goes unpunished. I found one of the thermostat lower housing bolt holes to be over-bored and filled with thread sealer: Of course I discovered this after I had reconnected everything, got my 280Z to start, and then when the T-stat opened, it showered the connections and proceeded to cause a short and burned up my fusible links. So, I ended up ordering a new fusible links, a lower housing, and other parts and again was waiting for them to arrive. I got everything back together and it started but was really rough. I thought maybe I had swapped the thermo-time switch and water temperature sensor connections, but after tracing the wires back using the FSM and 1976 wiring diagram, I verified all was connected as it should be. When the engine is cold, it will start but idle really rough then eventually dies after a minute or two or applying throttle. I did the light test today from page EF-51 of the 1976 FSM, and I notice that there is no difference in brightness from the flashes of the light when cranking when the cold start valve is connected and removed. This was witnessed on the No.1 and No.4 injector connections, as the FSM instructs. The FSM states "if the lamp does not flash, or if the lamp does not become brighter when the cooling water temperature sensor harness connector is removed, it indicates that the control unit is faulty. Replace the control unit, and carry out the inspection again as described above." So my questions are: 1. Is there any other quick ways that I can determine that my ECU has failed. 2. Assuming I have a bad ECU, what is the reliability of used ECUs? Are they similar to the Transistor Ignition Unit where a used one that I find (I assume there is no more NOS available from Nissan) will be living on borrowed time and I could expect to have the same sort of failure at any given time, whether it is days, months, or years down the road? 3. If #2 is true and used ECUs will fail, has anyone tried the FAST EFI ($1,600) or other more reliable/modern fuel injection system that can chime in on their experience and whether this is a recommended option or not? Thanks in advance for any input you may have and thanks for reading.

I think you hit the nail on the head. I'll add that I think the S30's are very well engineered cars that can be worked on with a good set of metric tools and without many specialized tools. My 280Z also doesn't generate the same level of frustration of other older cars that I have owned. Caution: I may be biased and have an unnatural love for Japanese cars. There's no cost cutting measures that are prevalent in American cars (nothing frustrates me more than finding something stupid, like a $75 relay buried behind a dashboard assembly or door handles that just fatigue and break repeatedly, or overheating problems that never go away), no inherent complexity or need for special tools like German cars require, or reliability issues with other European makes. The only issues I have found is that my clumsy, large American hands are often too big to fit in small spaces. I think I said it before, but Japanese cars built up to around the mid-1990's were probably the pinnacle of automotive engineering, and that likely started somewhere around the time of the S30. Unfortunately, this golden age ended in before the new millennium, when Japan started playing the same game that all the other manufacturers do now, with impossibly difficult maintenance items, needless plastic and foam rubber coverings in the engine bay, technology that becomes obsolete in a few years, and components with limited lifespans only designed to last until the warranty expires. It is a joy to open the hood of the 280Z and just look at the L-series inline 6. I also love explaining to my kids or whoever else will listen what each component does and how it functions. I have become somewhat of a self-taught expert, using my mechanical aptitude, reading the factory service manual and fuel injection bible, and also with the help of the great members and resources of this forum. They no longer make cars like the S30 and never will again, which is why I intend to keep mine alive and driving for as long as I am able, as well as trying to cultivate and grow interest with my kids. The next generation will likely not understand how to drive a car with a manual transmission, or without backup cameras, blind spot warning lights, lane assist, traction control, power steering, and all the other electronic nannies that are present on modern cars.

So not the triumphant update that I was hoping to write this evening, but I did get closer to resolving my fueling issues. I'm pretty sure I have said it before, but I do absolutely love this site and all the helpful members. I was able to obtain a Nissan fuel pump and damper from a fellow member here that no longer needed the setup. This made me extremely happy, as I want to keep my 280Z as close to stock as possible, and I did discover a problem with my damper. I installed the new-to-me fuel pump on Friday and was able to test start the car on Saturday. It only took a few seconds to start! After warming up, a few throttle pushes to redline, and I had no more hesitation, and fuel supply pressure was right where it was supposed to be around ~35-36 PSIG. I think my whole neighborhood heard my shouts of jubilation. I then went to the rear of the car to check for leaks and found a steady stream dripping from above the fuel pump and into my bucket. I shut the car off and found my damper to be leaking. Luckily, I had the replacement one on hand, so I had to disassemble everything and install the other damper. I suspect my existing damper was on its way out, and the increased pressure from the factory pump (remember the aftermarket one that was installed by a PO registered around 12 PSIG less than OEM) blew a seal or something out? Anyway, everything is back together, but I am now waiting on an appropriate fuel line clamp at the pump discharge (PO used the wrong type and all the spare correct ones I have are too small), which should be here tomorrow.

I certainly had a Guardian Angel watching over me that night. Not that it makes it any better, but there was about 5 gallons of gas in the tank at the time of the incident.

Glad you made it home safe. That sucks to have two incidents like that in one day. Maybe you were just not meant to be at that Volvo meet.