S30Grit

Had a few hours to work on it today, spent most of it putting the new injectors in. I came to a few realizations: 1) (Rant Warning). I learned to NOT to trust parts willy-nilly from zcardepot.com. I purchased the injector holders on their site, https://zcardepot.com/products/fuel-injector-base-holder-trigger-280z-280zx-75-83?_pos=5&_sid=a8aee91be&_ss=r# because one of mine was cracked. I figured if I ordered them from somewhere, surely a Z parts specialty store would sell something that fit. NOPE. My two-piece OEM holders fit perfectly and they screw right in. These cheap parts from "Standard Motor Products" (which isn't named on the zcardepot product page) do not align with the screw holes on the intake manifold. It's close to aligning, but too far off to even get a thread in. Of course I had no drill/bits with me to bore them out, so I used some sand paper and a screw to 'bore' one of them out enough to barely fit. I cracked the other messing around with it. Frustrating to say the least. +1 for the OEM purchasers... Makes me scared about buying other parts for the Z. 2) CSV was definitely gunked up. Cleaned, soaked, and clicked the solenoid with some injector cleaner. It sprays now when given 12v w/fuel pressure. Likely too warm today for the thermotine to trigger it anyway (75F). And as discussed previously, CSV most likely isn't cause of my starting issues. 3) Battery voltage while car was off is around 12.2V. When cranking, it drops to around 10.25V. Battery isn't fully charged from all the cranking it's done lately, but these numbers still seem normal. https://tontio.com/auto-guides/car-battery/car-battery-voltage/ 4) It was getting dark and probably around 60-65F outside when I tried to start it for the first time today. I couldn't even get it to start on starting fluid (only sputtered). This is probably the coldest outside temp I've tried to start it (unsure if related). Also it maybe has some air in the fuel lines that needs to clear out, and since my injectors aren't firing (#5 below), not sure the air was getting pushed out. 5) To sanity check the mechanics work, I checked one of the injector wiring harnesses. While cranking, an LED on the harness did NOT turn on. While messing with the key in the ignition, I saw the LED flicker 1 time, not even a "pulse" but a flicker. I'm still determined this is the cause. Something in the ignition assembly (even tho it's new) or other EFI wiring must not be connected/grounded right. I found it bizarre with the key in the ON position, and the motor not started: both pins on the injector harness had +12 volts. Either pin would light up a test light with the other end grounded. One pin is supposed to have +12v at all times, but I thought the other pin should be floating, waiting to ground pulse to complete the circuit. Tomorrow I'll be doing FSM tests related to this circuit tomorrow.

That was definitely a problem when I first got the car, but the mechanic drained a good amount of fuel and put in fresh fuel about 2-3 weeks ago.

Sure thing, I'll give it a go. I don't have easy access to a battery tender where I'm at, so for this test I may also run jumper cables to the car. Testing two variables at once, but still useful data I think.

This is one vacuum hose that isn't OEM and doesn't seem to be sealing properly. Might try clamping it before replacing to see if that helps. As for the AFM, not sure how that guy works yet. But I think the FSM has some basics checks that I can do on it.

Dave WM - Ambient temperature has been around the 80's previously when trying to start, so I'd guess coolant/engine temp wouldn't be too much lower than that, maybe 70F if I had to guess. Thanks for the video. Definitely good to know that it should crank right up without issue in warm weather regardless of CSV! I'll check mine just out of curiosity

This does seem ideal. Right now, my main focus will probably be tracking down the injector signal pulse issue since I know they aren't firing (and checking CSV). After that, I'll be re-confirming those previous things like fuel pressure and strong spark, etc..

I've definitely tried some starts over 5 seconds (and yes, my hand gets tired with just that due to the small key!). 15+ seconds hasn't been tried, but is that extra strain on the starter motor? I've always used starters sparingly (i.e. <5 seconds) my whole life due to concern of heat/wear on them for long starts, but that may be a completely unfounded concern! I've also tried some ~5 second starts, waiting 10+ seconds, then repeating. But I'll try some other approaches as well.

Ahh, good point, seems then that CSV alone likely isn't the cause then. But it's easy to test so I'll check it out. Im swapping the injectors right now because one is seeping gas, and a bit of a safety harazard. More to come...

There definitely hasn't been a shortage of ideas, which is much better than the alternative! Gives me plenty of things to check. The main question I have right now is regarding the CSV. If the CSV is used during startup, is the computer not supposed to pulse the injectors? Just good to know what the expected behavior is. I didn't see anywhere in the FSM describing if the car is supposed to use the CSV AND the injectors while cranking. If car is supposed to only use CSV or injectors: very likely a CSV/thermotine related issue. If car is supposed to use both fuel methods: I'm looking at some much tougher troubleshooting.

Ahhh, I knew I forgot one thing on the "new parts list". It has a brand new ignition switch assembly btw. I didn't install it, so maybe I'll re-check the wiring. Spark could be an issue, but I know fuel is an issue (99% sure at least) since the injectors aren't putting fuel in during cranking. Is the OEM 1978 module HEI? I'll have to do some research, is there specific part/manufacturer you recommend?

Yeah, sorry about the pic. Photo was taken a few days ago during troubleshooting. Definitely had the issue regardless if the CSV was connected or not. Either way, I'll be sure to do some more tests on the CSV soon. Zed Head - thanks for the clarification, that's very interesting it's an independent system. I'll try that starting procedure to see if I have any luck. There's definitely been some starting attempts, waiting various amounts of times, and trying again with no luck. I'll give that timing a try tho. However, given that it will fail to start in 80F weather, doesn't that mean it's likely not a CSV issue? I'm still operating under the assumption of this question: "Is it correct to assume that the CSV is only used in conjunction with the normal injectors?" Still extremely puzzled why injectors refuse to fire when engine is cranking regardless of CSV, thermotine, etc... not to say it's not the cause, just having trouble putting the pieces together.

Sure thing, here's two images. I'll take a closer look at your image and compare, but first glance looks ok? And yes, mine is a '78, hopefully plumbed up like one.

Thanks for the quick responses. I'll definitely check out each of these things this weekend. It's been 80+ F where I'm located at (SF bay area). Maybe a dumb question: Is it correct to assume that the CSV is only used in conjunction with the normal injectors? i.e. never in isolation? I didn't see this operation described in the FSM. If CSV and normal injectors are only used simultaneously, then I'm still very puzzled why the injectors aren't getting signaled to spray on cold starts. The mechanic used a specialty light for injectors (not a simple test light), I can try listening to the injectors but I'll expect a similar result. This weekend will be more chilly, below 70F in the morning for sure.. either way, I'll see if the CSV is 1) getting signal to spray and 2) actually spraying. And depending on those results, 3) manually triggering the CSV to spray and attempt to start. I won't be expecting the ECU to trigger it to spray if the coolant is above 70F, like Dave WM said - which could point to a water temp sensor issue if I'm not mistaken.

Hi All, I'm new to the forums and recently acquired a 280Z! I'm really excited about the car, but I did make the purchase with it not running. The interesting (and very bizarre) issue I'm having is that the engine refuses to start on it's own when it's cold. The weird part is that with a quick spray of starting fluid (3 sec), the car starts up and RUNS instantly and idles/revs using it's own EFI without problem. If I leave the engine idling for a couple minutes (not even up to op. temp.), then kill the engine, it will subsequently start on it's own without the need of starting fluid. It appears to only be cold starts where the car refuses to start on it's own. After letting the engine fully warm up, I can start the engine just fine several hours later without starter fluid. But fully "cold" starts it will always fail without starting fluid. A trusted mechanic and myself have tried several things, and consulting the FSM as well. I'll be working more thoroughly through the full EFI troubleshooting FSM this weekend to make sure we haven't missed something. During a failing cold start, what is known: Fuel pressure is correct/consistent at the fuel injectors during priming and starting sequence Spark is present Timing of the engine seems fine once it's started/idling via spray Fuel Injectors simply appear to NOT be receiving a signal to fire during startup (in-line light test was done). [obvious red herring here]. The weird part is that obviously after the starter spray is used and the engine starts, the fuel injectors start working. Previous owner and myself have thrown a few new parts at it without necessarily diagnosing each component: Spark plugs/wires, starter motor, battery, fuel pump/filter/regulator, some vacuum hoses. Troubleshooting done already, that has not changed the symptoms: Swapped in a different ECU (although I did notice that the ECU part number appears to be for an automatic A11-601000 while the car is a manual. But after reading, apparently the ECU's are actually the same) Cleaned misc. electrical connections everywhere I can think of (although I know I'm missing some areas) Checking fuses and fusible links Swapped in new EFI relay Unplugging a few sensors/connections to remove those variables (typically in isolation): thermotine, temp sensor, CSV. My understanding is that regardless of this configuration, the injectors should be getting a signal to fire on startup anyways though. Seems like an electrical gremlin, but running out of ideas to kill it, other than hooking up a NOS system as my starter fluid (kidding). I'll be spending a lot of time with the multimeter it seems, but any ideas what component/wiring could cause this?