SoCal'77 Posted March 17, 2015 Share Posted March 17, 2015 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 ) Quote Link to comment Share on other sites More sharing options...
NewZed Posted March 17, 2015 Share Posted March 17, 2015 Bear. Should have joined about $1000 ago. You've described the past, but there's not much about the present. What is today's problem? All I can get is sometimes the engine dies when you shut the door. Quote Link to comment Share on other sites More sharing options...
SoCal'77 Posted March 18, 2015 Author Share Posted March 18, 2015 (edited) 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. Edited March 18, 2015 by SoCal'77 Quote Link to comment Share on other sites More sharing options...
stravi757 Posted March 18, 2015 Share Posted March 18, 2015 The wiring is a mess. Start there! If you stock harness is too beat up, just replace it. As far as you problem with the car shutting off, who knows, sounds like there are many things that need to be gone through. But my best guess with the info we have would be your power transistor. It sits under the passenger foot well. Quote Link to comment Share on other sites More sharing options...
NewZed Posted March 18, 2015 Share Posted March 18, 2015 Signs do point to the ignition module (stravi's power transistor, there's one in the module). "my tach would go ape-shit". The noise from the fuel pump relay is what happens when the engine is about to die. No air through the AMF to keep the pump contacts closed. You've done so much work on it that it's hard to tell where to focus, but, if you're desperate, wire in a GM HEI module, for ~$20, disconnect your stock module by the fuse box (insulate the wire ends so you don't get a short), and see what happens. It's a fairly common problem, the tach behavior and the fact that it revives after cooling down are signs. But, search around on HEI module swap for 280Z's first and see what you think. Quote Link to comment Share on other sites More sharing options...
SoCal'77 Posted March 18, 2015 Author Share Posted March 18, 2015 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. Quote Link to comment Share on other sites More sharing options...
NewZed Posted March 18, 2015 Share Posted March 18, 2015 Slapping is generally a bad idea. A loose distributor shaft won't cause your tach to "go nuts". EFI with a return line on the fuel supply doesn't vapor lock. Fishing around isn't necessary when the full FSM is available through the internet with detailed diagnostic procedures. You need to find a full size screen so you can do some study. Get a meter and open the FSM and generate some numbers that tell you something. Quote Link to comment Share on other sites More sharing options...
SoCal'77 Posted March 18, 2015 Author Share Posted March 18, 2015 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 Quote Link to comment Share on other sites More sharing options...
SoCal'77 Posted March 18, 2015 Author Share Posted March 18, 2015 Perhaps its getting too much fuel Quote Link to comment Share on other sites More sharing options...
SoCal'77 Posted March 18, 2015 Author Share Posted March 18, 2015 Because of the constant power to the fuel pump and the constant supply of gas Quote Link to comment Share on other sites More sharing options...
NewZed Posted March 18, 2015 Share Posted March 18, 2015 Because of the constant power to the fuel pump and the constant supply of gas This is completely wrong. Seems like you've got the skill with hand tools but you don't understand how electronic fuel injection works. No offense, but that's what you're showing. It's important to know at least the lowest basics to make these things run right. The Engine Fuel chapter of the FSM does an excellent job of explaining how the system works. You gotta read it. The fuel pump is on all of the time that the engine is running. If you take an 8 hour drive, the fuel pump had power and pumped fuel for a solid 8 hours. Quote Link to comment Share on other sites More sharing options...
SoCal'77 Posted March 18, 2015 Author Share Posted March 18, 2015 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 Quote Link to comment Share on other sites More sharing options...
SoCal'77 Posted March 18, 2015 Author Share Posted March 18, 2015 I'm only trying to provide details that may help Quote Link to comment Share on other sites More sharing options...
NewZed Posted March 18, 2015 Share Posted March 18, 2015 List the numbers that you got from the "bible" tests. Coolant temperature resistance versus temperature (measured at the ECU), fuel pressure with and without the vacuum hose connected, ignition timing, etc. Describe what parts are on the engine now, AFM (is it the right part number), distributor, ignition module (is it the stock 1977 unit?), PCV system (all of those hoses on top and under the intake manifold) complete and properly connected, etc. Then describe n detail, with numbers like seconds or minutes, what the problem is. "It dies then takes 30 seconds of cranking with the fuel pump off to start" or similar, whatever describes the situation. Engine dies, won't start is too vague. The EFI system has a lot of parts and they are all connected, and need to be working right. Any one of the things I mentioned above could screw up the way your engine runs. Quote Link to comment Share on other sites More sharing options...
SoCal'77 Posted March 19, 2015 Author Share Posted March 19, 2015 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 Quote Link to comment Share on other sites More sharing options...
seattlejester Posted March 19, 2015 Share Posted March 19, 2015 You need to slow down, this is a different kind of forum, assumptions don't help you or us. Sit down, take a breath. You obviously felt you needed help by coming here and posting. Let us help. We need facts, unfiltered and clearly laid out. If you assume that the car is running fine before it dies, that is a problem in and of itself. We need to know how fine it is running. That means temperature, oil pressure, voltage, time it runs before shutting down, attributes when it shuts down, how long do you wait before you can drive it, what is the temperature outside. Hard numbers and facts. Best way to convey this information is in a list. Car dies when... It is ____ degrees outside It has been running for _____ minutes After cooling for ____ minutes I can start it again It takes _____ seconds of cranking before it starts The battery voltage is ____ volts at resting The battery voltage is ____ volts while running The coil is _____ degrees when it dies The coil is _____ degrees when I can start it again Everything you state should have a number/observation and unit associated with it. We can help or at least steer you in the right direction if you give us facts. Assuming that your electrical is fine (see how bad assumptions are? I can just gloss over everything with that), the "works for a while" problem comes down to a couple of possible problems. Fuel starvation, spark starvation. If it is running for a while that means the air and compression are ok for now. Fuel starvation breaks down into... Fuel supply insufficient, you said you have a regulator, does it have a gauge? Vapor lock is a thing on these cars especially in hot weather, it may be time to look for a fuel line cooler fan from a 280zx. Spark starvation... Insufficient spark won't light the mixture. Check the spark plugs, in fact take them all out and post them in a row and take a picture that in itself will tell a story. Check the coil when the car dies, is it hot to the touch? What's the car's voltage running and not running. You have a choice to make right now as well. Do you want to learn or do you just want a running car. If you just want to have a running car (there is no problem with that at all) take it to a shop. Have them sort out the electrics and slap on a warranty and drive around and enjoy it. If you want to learn yourself you have to invest, that means time, money, effort. You can't just have that kind of wiring mess sitting around. Get some decent tools and fix it. I see in-line un-covered fuse holder, open contacts, exposed fusible links. Quote Link to comment Share on other sites More sharing options...
NewZed Posted March 19, 2015 Share Posted March 19, 2015 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 It's a flyer, but that is somewhat symptomatic of a bad ECU or bad ECU connector. The door slam = die also fits. People have had the "blue smoke" problem while the engine is running and fixed it by pounding on the side of the ECU, or wiggling the cable. Not kidding. Others have found that the solder joints at the ECU cable connection are cracked, causing the blue smoke problem. They reflowed the solder joints. I had an ECU that would just die out of nowhere, then restart a minute later. I knew my problem was the ECU because I had just installed it to make sure it was good. Unfortunately, the tests won't pick up a bad ECU. Mine was a bad transistor, the others were bad solder joints. So you can either beat on the side of the ECU, or wiggle the cable or borrow an ECU and try it. One case where swapping parts makes sense. Even at the end of all of the FSM testing, if you don't find the problem it usually says "replace ECU". Quote Link to comment Share on other sites More sharing options...
SoCal'77 Posted March 20, 2015 Author Share Posted March 20, 2015 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 Quote Link to comment Share on other sites More sharing options...
SoCal'77 Posted March 20, 2015 Author Share Posted March 20, 2015 That may also explain why my fuel pump gets constant power when its on the factory circuit Quote Link to comment Share on other sites More sharing options...
noelawinslow Posted April 23, 2015 Share Posted April 23, 2015 If your ecu was replaced recently then likely there was an issue that knocked it out in the first place, which would make me more likely to suspect the ecu and try to track down the murderous short. Quote Link to comment Share on other sites More sharing options...
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