SoCal'77

I do have power to the injectors but i should check while its stalling, i have not tried starting it with starter fluid. The most recent update Okay so I took the car out last night around 60 degrees ran fine (didnt push it hard) today its been sitting in the 85 degree sunlight and when i tried to start it, it would turn over but run very choppy while blowing smoke. if i gave it gas it would shoot up to 2-3k rpm healthily before it would start choking and cutting down. eventually the car died out, doesnt want to start up. bet if i wait until about 7 oclock it would start up fine. as you said checking the spark strength, is there something that could reduce the power of the spark due to surrounding temperatures?

Hey, been a while but ive had some other ups and downs with the car since but it is currently running well, could use a tune up and new plugs although still having this mystery problem of dying after a while of running. I was reading an article that mentioned the later 280zx's fuel pump engages as soon as the key is turned, while the 280's fuel pump only kicks on when the starter cranks. In my z, the fuel pump acts like a 79-83 zx by turning on as soon as i turn the key to the accesory position. perhaps it contributes, i suspect it does. but ive provided most of the information accoring to seattlejester's chart i do have spark and fuel pressure when the car wont start "the car dies when" It doesnt matter how hot or cold it is, the car will die, although a warm day will bring about the problem sooner It has been running for 10-15 minutes After cooling for 30-120(depending on temperature and/or direct sunlight) minutes I can start it again It takes 3 seconds of cranking before it starts when it decides it wants to start again The battery voltage is 12 volts at resting The battery voltage is 12 volts while running i dont know how warm the coil is when it dies i can go for a run The coil is no longer warm before it can start again

That may also explain why my fuel pump gets constant power when its on the factory circuit

Forgive me for leaving this part out but my ecu has been replaced a few months ago. That being said Im sure it may be time to look at the wire harness in greater detail. I've fixed some shotty looking worn sections of it already around the ecu. I'm sure the extent of which goes further than what I've seen

Ill rerun the tests tomorrow and update you with numbers. Everything is stock except for the fuel pump. Everything is properly connected. When my car does die sometimes it can easily get started if crank it and push the gas for a few seconds. When its problematic ,mostly occurs on a hot day, it can only get started when the pump is off. Because I have a adjustable fuel pressure regulator on the return line in between the fuel rail and the line that goes back into the tank, it the engine will stay running with the fuel pump off for about 30 seconds. The only way I can get it started is with the switch off, crank the engine, and then from that point I'd have to pulse the fuel pump switch while holding a bit of gas, this whole time its blowing a blueish gray smoke and running choppy. If I let off of the gas the engine would die

I'm only trying to provide details that may help

Obviously I have been struggling. I've studied the fuel injection bible and ran the tests. I wouldn't be here if I weren't stumped. Which numbers do you want to know, what measurements are helpful know.from what I've gotten you want me to test the power transitor

Because of the constant power to the fuel pump and the constant supply of gas

Perhaps its getting too much fuel

The only numbers that would be worth anything would be the ones while its breaking down, it runs great and healthy all the other times, replacing the dizzy and coil completely fixed the wild tachometer problem. I'm assuming that when this current problem occurs I'm losing fuel pressure. That's what it looks like and that's what it feels like. Because my fuel pump is on a switch I can control the pulses, and that's what it takes to get it started, although very rough. Sometimes if I hold the choppy idle about 1500 it clears the chop and restores function Spark plugs are black as coal

The Tach had calmed down after i replaced my distributer, the shaft was loose, and any time i would accelerate/down shift it would go nuts. thats solved Ive currently got a zx electronic ignition distributer waiting to be put in but figured id do some more research before i slapped in more parts. Im looking into ignition module now.

Yeah I just provided that information so you would know what ive done in the past that would affect the current problem, but no kidding, So as of now the car shuts down after prolonged use, seemed vapor locked when it does. Car must wait long time before can start up again My current theory is because the fuel pump is on its own circuit and is flowing at all times. In theory if i remove the standalone system and patch up the wires like factory, the fuel pump will turn on the second the wires make contact. Thats where I stand as of now. And the intermittent electrical problems i.e doors=shutoff, windows, stereo. im fishing around the idea of the fuel injection relay being fried but i dont want to just get another one and have something throw it out again in a few months.

Hey guys, just made a fresh account on the forums, figured it was about time to join in on the fun. For the past 6 months my Z has been having a shit storm of electrical and fuel problems. So where do i begin, I bought my 1977 280z about 9 months ago, i used to drive it to work a good 30 miles each way and it never gave me any issues until about 2-4 months in. on a rather warm day I was showing off my new car to a friend of mine, another datsun enthusiast, when all of a sudden i start losing power and my tachometer roughly drops. I could keep it alive for a bit if I would clutch in and work the gas but all in all it only delayed the inevitable. To get it home i cycled the key a few times, waited a few minutes, and after a handful of failures i managed to get home without any more hiccups. from that point the health of the car deteriorated very slowly over a long period of time. Now before i got this car I wasnt very mechanically inclined, I have basic skills, I know how to take peices off and put them on again, still learning. I knew i would get problems down the road and I was prepared to make the necesary repairs. I used the forums to point me in the right direction, and i know its not the right way, but i basically used hints of snippets of information to choose which replacement part i would throw into my car. I started fuel injector cleaner which seemed to work for like a week. after that i put on a fuel pump because it seemed like I wasnt getting pressure, I did not put a guage on or checked the pressure, i just put it on. I know, slap myself. (didnt learn either). I drove for a while then again the same problem would occur, which i then began to figure out may be vapor lock, very possibly still is. From there I got a oem replacement fuel regulator, which also seemed to work for a while, but ultimately failed, So as weird as it sounds, I chose to do an oil change about that time, which really did stop the issue of my car. I drove around for a few months on a leaky head gasket, I had it checked by a shop they said it was fine so long as i didnt get the sluggies in my radiator or coolant in my oil, which i wasnt. I waited for some help before I replaced the headgasket, got that done way later than it should have taken. drove drove drove and then guess what happens? it went kaput again. From that point i replaced the Afm, distributer, coil, alternator, 2 fuel injectors, and very recently i put an adjustable fuel pressure regulator on and set it down to 30-36 varying.I forgot to mention, before i replaced the afm, my tach would go ape-shit, my fuel injection relays by my foot would click to high hell, and eventually my fuel pump begain to stay on. the quickest solution i saw was to disconnect the battery. for about 2 weeks i rode around with a super-acces panel over my batery. I had my local datsun guy hook up my fuel pump on a stand alone system with a kill switch and a relay and all those goodies as a temporary fix but now my afm no longer controls my fuel pump shut off. I tried restoring the factory wires after i replaced the AFM but the same problem where the fuel pump kicks on automatically still occurs. Bare with me guys, im just trying to give any and all background of my vehicle so we can slim down the options When I had bought the car it had a sterio system put in with an amp and subs, it also has power locks, windows, and an alarm system. All of these I am suspicious of because sometimes my car will shut off if i close my door too hard. Recently the windows are intermittent, the sterio is on "PROTECT" because of a short somewhere, I want to just gut the whole system. Air conditioning unit has been deleted, heater doesnt work, horn deleted because im pretty sure it would short out and shut down the car. I apologies if this post makes you angry because of what a green horn i am, but if you have the patience to help me save my datsun..... It would be great! Let me know what im going to have to clarify because i know i will. thanks in advance ***The image in the thumbnail is of the mickey mouse wiring from the previous owner, along with the standalone fuel pump system tucked in next to the battery. Before the fuel circuit was installed the old wires that originally sat in the box (i want to say fusible links), we're just cut and leading to nothing*** (also in the image the wires that are disconnected hanging loose ( red yellow white white-red) was my attempt at restoring back to factory setting, so as of right now the fuel pump does not turn on with the kill switch or ignition )