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First post here but have been a spectator for about 4 months trying to absorb as much information as possible. I recently obtained a 1975 Datsun 280Z from my neighbor who purchased the car new as an anniversary present for his wife. He owned the local Datsun dealership at the time so all maintenance was done by his dealership. She drove the car until it had about 106,000 miles at which time she got a new car with an automatic transmission (this was a 4 speed car). The car has had a pampered life. She always garaged it and took good care of it. He put a non op with the DMV, pulled the plugs and oiled the cylinders, drained all of the fuel out of the tank and parked it under a large carport in 1995. I purchased it late in Dec. of 2020 and have been slowly working to get it back on the road. I have run into an acceleration problem that I hope someone can help me to diagnose. Since I know from reading past posts , members will want to know details so here goes. I have replaced all of the injectors (corroded terminals and age) and their electrical plugs. New electrical plugs on the water temp. sender as well as tested its ohms output when cold and hot. New gasket with sealant on the cold start injector as well as a new electrical plug. New spark plugs, wires, rotor and cap. Verified distributor advances when a vacuum is pulled. Pulled the gas tank (it was clean with not rust) replaced all of the fuel lines by the tank as well as in the engine compartment. Verified the strainer was clean, replaced the fuel pump (gaskets dried out so much it leaked like a sieve) and installed a new fuel filter in the engine compartment. I replace all of the vacuum lines, pulled every plug that I could find to clean them. Pulled the pan to replace a leaking gasket (had a very small amount of sludge in the bottom) refilled the oil and a new filter. Pulled all the plugs oiled the cylinders, cranked it over until the oil came out of the cam/lifter oiler on top. New plugs, new valve cover gasket, turned it over and it fired up. Let it come up to temp. reset the timing to 10 degrees at 800 rpm as per factory specs (I have the factory service manual). Thought this was really going well until I tried to drive it. It accelerates up to about 2500 rpm and then it falls flat on its face. Pulled the AFM and started checking the pins, all looked good. Went thu the Service manual ECU checks, all looked good. Checked vacuum at idle when warm 18 in. of Hg. Pulled the plugs and checked compression- lowest 152, highest 160. Installed a air/fuel gauge on exhaust right below the manifold and found it idles at about 12.7 and 13.0 when warm. Try to drive it and it goes so lean the engine stops and resumes when back to idle. Checked fuel pressure and static is puts out 36, when running it sets solidly at 32. I know the FSM states 36 psi but is 32 that out of wack? Started looking for a vacuum leak and I thought my problem was found when I found a leaking brake booster so I plugged the port at the manifold and took another ride but no change. I opened the AFM and loosened the spring tension about 5 gear teeth and still no change. If I bring the rpms up very, very slowly I can get it to rpm beyond 3500 but not when driving. I don't think it is an electrical (distributor) issue because of the ability to rpm over 3500. I've checked and cleaned the points on the throttle switch. I've watched the position of the idle enrichment contact and it opens right off idle and the full throttle contact is not making contact when the engine goes lean. Any suggestions or recommendations on what else I can check would be immensely appreciated.

Still trying to get this 78 running...old mechanic working on it for me ( I know very little)...have drained tank, PO seems to have cleaned it; new fuel pump (walpro); gaslines blown out; fuel pressure tested at filter(new) at about 45#; he says he checked and cleaned(?) all electrical connections; new fuel injectors (ebay) and seals; AFM cleaned. Now he says he checked the TPS, cleaned contacts and it runs "better" but not like it should...aftermarket TPS seems to be only available now thru the zcar place in Ariz at $125.+ Any suggestions before I throw more parts at this thing?

Hey everyone, I have been a long time lurker on many forums and I have decided to post some questions because I am at the point where I believe I need guidance on next steps and want to make the right decision. The car I am working on is a 78 280z California Car. It is not my car, it is my parents car that I bought them as a gift 10 years ago. It has been a long time since I have driven the car so I don’t recall its characteristics but it always had a presence of fuel smell in the exhaust. The car was parked because the fuel smell and rough driving started getting worse. The car then sat for a year and a half and now its time to get it back up and running. All the items addressed have been done within the past four months. Disclaimer: There is a lot of information here and if I am unclear on anything please let me know. I am trying to get some conversations going and wanted to put my best foot forward. Symptoms Bogging/hesitation/stuttering under any load to the point where the car can’t be driven, can’t emphasize this enough. Car idles immaculately Backfiring through the AFM Fuel smell through exhaust Current State Timing: 10° BTDC Idle: 800 RPM Aftermarket exhaust header and muffler EGR deleted Air regulator removed Coldstart injector still on rail but disconnected electronically Thermotime switch disconnected electronically Items that have been addressed Spark: New Plugs (NGK at .039in gap) New Wires (NGK) New Coil (MSD Blaster) Rebuilt ZX distributor (RockAuto) Vacuum advance confirmed working New Cap New Rotor Fuel: New fuel injector connectors Injectors reconditioned from Fuel Injection Services (confirmed working) New Walbro 255 fuel pump Tank removed and checked for rust Fuel hard lines cleared with compressed air New fuel filters (pre and post pump) Inline gauge added between filter and rail Air: AFM has been calibrated per atlanticZcar site rebuild guide Bench tested for smooth sweep (open to close) Calibrated spring force with water weights New PCV valve Engine: Valves adjusted to: Intake: .008in Exhaust: .010in TDC mark confirmed correct on main pulley Distributer shaft confirmed 11:25 position Leakdown test performed Compression test performed Electrical: New coolant sensor New coolant sensor connector New TPS wiring connector Contacts cleaned with deoxit ECU Harness tested in car to EFI Bible specifications Results Leak down and compression test performed cold because the vehicle was not running at the time. The AFM sweep was performed using a 9VDC battery and an arduino. I did two sweeps of the door by hand as smooth and slow as possible. The third sweep I intentionally pulsed the door through the sweep motion by hand to see if something else would happen. I did not see any signs of a bad circuit. The FSM provides a table relating resistance to temperature for the air temperature sensor and coolant temperature sensor. I generated a chart using this data in both °C(Blue) and °F(Orange). The trend is not linear so a polynomial trend(Thin Orange) was generated so I could plug in a measured value to determine a temperature. The table also provides acceptable ranges within specific temperatures so I added error bars to show this acceptable range. The test environment(Green and Yellow circle) was what the temperature should be and the measured (pink) value was within the error bar at that condition. I went through the circuit testing per the FSM and found nothing alarming. Observations Advancing the timing beyond the timing marks helps but doesn’t resolve the overall issue. Timing at 10° makes the car impossible to drive. Timing at 25°-30° makes it bearable but only above 30% throttle. Future State I have worked through what I believe to be the cheapest items to inspect and now believe it is time to find a new AFM and ECU set. Everything appears to be correct and by the book. Should I try to find a 78 280z ECU/AFM for a CA car, or should I find one for any 280z car (non CA). I have toyed with going standalone because at this point I am tired of poking around in the dark trying to troubleshoot this car. I need some assistance from people who have experience with the FI systems on these cars and I don't know anyone locally to reach out to. If I am unclear on something, please ask and I will provide.

Z ran when parked Had it running in January after I chased down a misfire issue that came from a faulty ECU. She ran mint so I began my tear down, months later here we are and I thought Id have it running today but no luck. Heres what I got so far from trouble shooting. My battery is fully charged (tender says 100%), its less than a year old. My digital multimeter has it showing about 12.8 yet when I put the car on the "ON" position, my battery gauge in the dash reads about 8.5. I tested the ECU pins with a dmm and it will read 8 and change. Is this normal? Is this a fault in the voltage regulator? I tested the 6 pin connection that goes into the voltage regulator but didnt have much daylight to really spend time on it. About 3 of the connections read battery voltage, I think 2 read around 4.2 and 1 read really low, I forget the number. Fuel pump works when power is applied directly from an outside source (getting proper fuel pressure at my regular and fuel rail gauge when applied) but not from the car itself. The FPR reads 0 and you dont hear any fuel going to the rail. No leaks. Through testing the fuel relay from the ECU pins, I wasnt getting any reading so Im certain the relay is faulty. I bought that today and am just waiting for it. Could this potentially bad relay be causing all these gremlins? Spark is coming from the coil but no spark at the plugs. Something is up with the dist? I checked the AFM through the pins of the ECU harness and that looks perfect. Another small thing I noticed, when I hit my horn button, my tachometer will jump!! What is going on with my Z? Thanks!

Hello I just bought a 1976 280z, My first z but i have done a lot of research on them. It will start up easily and run cold well at around 800rpm. But once it warms up (the temp gauge is about in the middle.) It will drop down to 500rpm and stutter. If I give it barley any throttle to bring it to 800 rpm it is fine but if I go up to 1000-1200rpm it will back fire through the intake and exhaust. The plugs are back but not fouled. If I manually control the AFM it will run fine. I also unplugged the connector to the cold start injector but it did not seem to change anything. I am thinking the temperature sensor is the problem. also there might be some vacuum issues because of any dry rot (I plan to re-do all of the vacuum lines). I do not a lot about how the efi works on these cars except for the basics, and I would like to know how everything works. -Thank you

Update: Just want to thank everyone who has replied. I haven't fixed the problem but its great to hear other peoples opinions and suggestions! So i just want to start off by saying I am in no way an experienced mechanic. I am having a problem with my 1977 Datsun 280z and am willing to hear anyone's thoughts. So I haven't driven this car much. i bought it and it had a leak in the exhaust manifold. Since i had to take it all off i decided to buy headers. While removing the EGR tube, the tube was damaged so I decided to remove the EGR. I remove the EGR use a block off plate from a Z store. I capped off the vacuum that leads to the egr. Now for the problem. When in the driveway the car sound great. I can rev it as high as i want and it sounds perfect. when driving around normally it feels fine as well. The problem comes when driving a bit faster or opening the throttle quickly. When im driving and pass about 4000 rpms the car starts to sputter and i can smell gas. It feels as if its not getting enough air to burn the gas in the cylinder. If im drivng fast and step of the clutch and rev theres no problem. the sputter only happens when im actually putting gas to the wheels. Does anyone have any idea what can cause this? The fact that it acts so well in the driveway or with the clutch in throws me off hard.

Hey guys got my fuel injection up for sale because im not smart enough for it..lol im located in salem oregon.

Hi Z enthusiasts. I have a '78 280Z with 64k miles and is in stock condition. I have never had the problem I am having right now with it in the three or so years I've had it. It has just started to run somewhat rough, almost like it is not running on all cylinders, maybe down one. It holds an idle but is not as smooth as it used to be. When driving, it feels down on power throughout the rev range and no matter how much throttle is applied. At idle, it will gradually accelerate overall fine but still with somewhat of a stumble, and as mentioned down on power when driving. When more abrupt throttle is applied, the engine stalls for a second or so before it revs up. Below is a video of that symptom. I am looking for advice on where to start. The fuel tank has been restored when I first got it about three years ago. A couple fuel system items have been replaced (ex: filter, pressure regulator?, one injector, etc.). It seemed like clogged injectors were a common problem on these cars. Those can be checked with a stethoscope? I checked to make sure the plug wires were tight. It is bad enough to warrant not driving the Z. Thoughts? Regards, Shane

I have a 1977 280z with running issues. What's wrong is that when I start the car, it cranks over fine and will start fine but after the initial start it will immediately bog down and either die or run on like 3-4 cylinders :sick: It helps tons when I push the AFM in about 25% of the way, but If I let it go on its own the car sputters and bogs down again or dies. With the AFM pushed on full (the top cover is off) I can slowly push the car up to a fairly high rpm, 5000 or so, but I can't seem to do quick revs or the car will backfire even with it in all the way. Here are some of the things I've replaced: -New cap and plug wires (with relatively new plugs; they're NGK, don't worry) -New fuel filter -New seals for the fuel injectors -New fuel regulator -New coil Here are some things I've done: -Cleaned the fuel lines -Set the timing -Tested the fuel pump (It works and puts out about 36 pounds of pressure between the new filter and the rail) -Tried a different ECU and a different AFM (Both came with the car and both give the same results) -I did do a compression test awhile ago and everything was fine, and I should be able to do another compression test tomorrow afternoon -I checked to see if the injectors work by taking them fully out of the car starting it and see them all work correctly -I did check the voltage of the clips going to each of the fuel injectors and those all work fine -I checked the points in the ECU that go to both the AFM and the fuel injectors both also came out fine -I checked the electrics in the AFM itself and everything seems fine (it's also possible to hear the fuel pump working when the AFM is puched in slightly) If anyone has an idea of what might be going on please reply, I feel like by now everything should be working at least sort of correctly. I'm at the point where digging into my pocket and sending it to a mechanics shop or buying a Megasquirt system would be better than wasting anymore time on it. Would maybe replacing the whole AFM do me any good? Could it be a bad sensor sending a bad signal to the ECU? I appreciate anyone's input! ZDrummerGuy is online now Report Post Digg this Post!Add Post to del.icio.usBookmark Post in TechnoratiTweet this Post!

Hi I'm new to this page and the car only owning it for 2 months. Being 17 and being used to dealing with carburetors. So to the issue it is running rich I have replaced the coolant temp sensor and the 7th injector plug, have adjusted the air/fuel screw also but still getting too much fuel, please help.

I just had my tank media blasted, boiled, and sealed. While doing so I delivered a Competition Engineering sump to be installed as a part of my fuel system upgrade. When I got it back, instead of drilling out three - five holes in the floor of the tank and welding in the sump, they cut out the bottom of the tank the size of the while sump. As a result the sump is now not baffled. I don't like it and am not happy with it but the vendor basically said, "Too bad unless you want to pay us to fix it." I took my tank and left. I have a real concern about the sump not being baffled properly and in low fuel situations allowing for fuel starvation. Am I right to be concerned or am I worrying about nothing?

Hi, I wanted to clean my engine and the compartment yesterday. I picked up some spray from AutoZone, and was careful to cover and tape the coil (pulled the main wire to make it easier), the battery, and the distributor. I sprayed, let it sit, scrubbed a bit, and rinsed. I used a towel to wipe down, and then removed the tape and coverings. The engines started fine, idled fine, and I thought I was on my way. I took off down the street, but as soon as I got to 2,700 rpm’s the fuel seemed to simply shut off. It didn’t die, but picked back up around 2,200 rpm’s. I limped back home and found that some water got into the fuel injector clips. I took each one off and cleaned it out (blew what I could, used a bunch of baby’s q-tips to wick up the water and dry the unit). Unfortunately I had the same problem, and now the next day it’s the same thing… I can start up, and idle. I can drive if I shift gears early and keep the rpm’s down. If I am parked and simply open the throttle, it cuts at 2,700 and picks back up at 2,200… over and over and over. Help please. BaTora

Hey guys I need help converting my Datsun to fuel injected since I plan to put a l28t in her. I was just asking for tips and important things I need for the car. Also would be wonderful if you guys got any sites were I can obtain some parts

I have a 1971 240z and i want to know how hard it is to put in a fuel injection system or how long would it take?

Ok I have a 78 280z i bought not running and fully rebuilt internally. Something was "mentioned" about fuel problems when i got it but the internals were in need of rebuilding anyhow (slightly bent intake valves). I have got everything back up and going except that my injectors have NO POWER to them. I believe that charger wires were crossed on the batt also! So ive been checking for the injection relay-but there is much discrepancy between where it is located on the 78 Model. I found the one by the battery under hood, but the cabin one i did not see by the ecu or passenger kick panel? Anyone know WHERE the darn thing is or ift here even IS another one? the one i found looked ok. Or any suggestions on what else to do to solve the no power problem- maybe computer?? Thanks in advance sorry for the length- oh and proddate 02/78 SORRY for double post trying to delete!!

Ok I have a 78 280z i bought not running and fully rebuilt internally. Something was "mentioned" about fuel problems when i got it but the internals were in need of rebuilding anyhow (slightly bent intake valves). I have got everything back up and going except that my injectors have NO POWER to them. I believe that charger wires were crossed on the batt also! So ive been checking for the injection relay-but there is much discrepancy between where it is located on the 78 Model. I found the one by the battery under hood, but the cabin one i did not see by the ecu or passenger kick panel? Anyone know WHERE the darn thing is or ift here even IS another one? the one i found looked ok. Or any suggestions on what else to do to solve the no power problem- maybe computer?? Thanks in advance sorry for the length- oh and proddate 02/78

I just bought a 280z engine for my 240z. It's got fuel injection so i'm removing it for carbs. I know what I need to do to take it off, but i don't own an air compressor or tools for them. Is it needed? or am i able to get by with had tools. I've also taken off the clutch and flywheel to mount it onto the engine stand. I assume to get the clutch back on it might take a little extra torque. Any help would be great. Thanks.

The car starts up pretty well, though every once in a while it'll immediately die, and takes some coaxing with the accelerator to get it to stay running. When idling, at first rpms will hover around 800-850, then slowly drift down. The car starts running rough, rumbling, until it gets down below 700 rpms and dies. Also, when coming to a stop and idle after swift acceleration, the car stinks of exhaust fumes and gasoline. Is this a fuel injector problem? I was going to replace my fuel filter; would that be a waste before i know what's causing the problem? --------------------- 1976 280z Automatic