viasloth Posted December 26, 2011 Share Posted December 26, 2011 (edited) Hello, im new to owning a Z I received it from a friend of mine and have been having problems with getting it up and running its a 78 280z with EFI. now Ive been having a lot of problems tracking down what is actually the problem or if its multiple problems, but ive not got it to the point i can start it put only if i disable the starter and let the cold start valve inject some a fuel a couple times then when i enable the starter again it will fire right up but wont stay running. so now i have a feeling it might be injectors or AFM other then that i have no idea and if thats the case i cant afford to buy a new AFM or all new injectors for that matter either since either would cost me at least $300 from what i can find. so im wondering if there might be a write up somewhere on how and what i would need to do a carb conversion. cause i can get an intake and carbs for the 240z SU carbs. thanks for the help Edited December 27, 2011 by viasloth Quote Link to comment Share on other sites More sharing options...
dhartig Posted December 27, 2011 Share Posted December 27, 2011 Fuel + spark + timing = running engine. You have spark, how it smooth it runs tells you timing. Clean your injectors and check your fuel pump pressure. Carb conversion will need different fuel pump and is a long process. Start with the easy stuff. BTW, the period (.) can be your friend. Quote Link to comment Share on other sites More sharing options...
viasloth Posted December 27, 2011 Author Share Posted December 27, 2011 well i just got some parts from a friend. I'm gonna swap out the ECU and AFM. I cant tell how smooth its running because it wont stay running for more than a few seconds. I'm gonna try and hit the junkyard this weekend in hopes of finding injectors. but the only ones i might be able to get are off a 300zx and im not sure if those will work or not. And the reason I'm asking for a write on the carb conversion now is because id like to have it ready in case i end up having to go that route and not have to fly blind and guess. Quote Link to comment Share on other sites More sharing options...
ttodhunter Posted December 27, 2011 Share Posted December 27, 2011 (edited) You might want to see if the AFM is actuatiing the fuel pump. You can either pull the front intake boot off or the black cover from the drivers side of the AFM, then move the flap or the lever arm (with the key in the run position) and see if you hear the fuel pump switch on and off. You could also have a friend start the engine while you hold the flap or arm open a little bit and see if the car stays running. Just a thought... Edit: I just remembered, the 77+ Z's use the oil pressure switch or alternator current to activate the fuel pump. This test will not work for you... Edited December 27, 2011 by ttodhunter Quote Link to comment Share on other sites More sharing options...
MuhKaydenZ Posted December 27, 2011 Share Posted December 27, 2011 I was having issues getting my car to fire. What I did was take some wire and jump the fuel pump to make sure fuel was getting to the rails. The next thing was to unplug the connector at the alt which will make the fuel pump constantly run. What I should have done was check the fusable links because one of mine wasn't making full contact and that's why the car wasn't running fixed that and now I can have the plug plugged into the alternator and everything is running great hope this helps. Quote Link to comment Share on other sites More sharing options...
viasloth Posted December 30, 2011 Author Share Posted December 30, 2011 ok so now it will fire up first try, then quit running, then if i wait awhile it will fire again then quit running. any ideas? Quote Link to comment Share on other sites More sharing options...
soga280z Posted January 3, 2012 Share Posted January 3, 2012 Hello, when i got my first z, it would fire then quit. I would recomend getting/ making a fuel pressure guage and put it after the fuel filter and see what kind of presdure your getting. Depending on what pressure you have will help decide in what needs to be checked. Good luck Quote Link to comment Share on other sites More sharing options...
Pharaohabq Posted January 6, 2012 Share Posted January 6, 2012 You might check all your grounds, since that can cause intermittent issues like that. Also your fuel filter might be clogged, choking off fuel. A bad afm can also cause that. Quote Link to comment Share on other sites More sharing options...
surpip Posted January 8, 2012 Share Posted January 8, 2012 (edited) I would almost guarantee its something as simple as the filer being clogged, but as stated ^ check all connections more importantly the ones to the temp sensor's and AFM, and check fuel pressure even if you do it just buy your fingernail on the shredder valve while turning it over to make sure you have pressure. But I’d be willing to bet it’s your filter Edited January 8, 2012 by surpip Quote Link to comment Share on other sites More sharing options...
viasloth Posted January 8, 2012 Author Share Posted January 8, 2012 filter is fine its brand new, i ruled that out when i first got it. im in the process of change the injectors and the pressure regulator and i have 3 AFMs to try and 2 ECUs so im hoping this will fix the issues if not im still tryin to find a write up on converting to carbs. tomorrow i should have everything back on and know for sure Quote Link to comment Share on other sites More sharing options...
NewZed Posted January 8, 2012 Share Posted January 8, 2012 1977 still has the contacts in the AFM according the FSM (Factory Service Manual - http://www.xenons30.com/reference.html). If the contacts in the AFM are dirty, the fuel pump will only run when the key is at Start. Your symptoms sound like dirty AFM fuel pump contacts, or an intake system leak that bypasses the AFM vane. Post #4 was actually a good idea. If that didn't work, then checking that the injectors had power and were actually firing would be next. Probably too late though since you've moved on to the replace and hope method. You might get lucky with an AFM, if it's the right model. Quote Link to comment Share on other sites More sharing options...
viasloth Posted January 8, 2012 Author Share Posted January 8, 2012 Well from what Ive found out the 1978's fuel pump was actually attached to the oil pressure switch instead of the AFM. Also my fuel pump works fine and turns on when I turn the key on. And the reason Ive decided to start replacing my injectors is because I was just gonna replace the pressure regulator and decided I should check the condition of the injectors and they are pretty trashed to the point the were almost falling apart. Quote Link to comment Share on other sites More sharing options...
NewZed Posted January 8, 2012 Share Posted January 8, 2012 Well, those are new details. If that's the case, then you should focus on getting the injectors to open correctly and squirting fuel. The point is that you aren't sure what you're trying to fix. You have spark and fairly correct timing (because it runs off CSV gas), and some fuel pressure (because the CSV is getting enough gas to run the engine for a short while). You should measure the pressure before you replace anything, test the injector connectors for voltage and signal from the ECU (with a test light or other method) before replacing the injectors, test that the ECU is getting the proper signal from the coil before replacing the ECU, and test the AFM before replacing it (swapping AFMs to get it to idle won't be very effective, if your fuel pump is hot-wired to be on all the time). You might be replacing good parts with bad ones. You won't know unless you do some investigating and take some measurements. It will save you time and money and lead to better results in the long run. Good luck. Quote Link to comment Share on other sites More sharing options...
surpip Posted January 8, 2012 Share Posted January 8, 2012 If your tank is full of crud it fills up and restricts the filter almost imidiatly. I know because my 78 280 did the same thing, that's what it sounds like to me. i dropped my tank and used that coating you can get off of ebay. it worked great if i remember correctly if you have spark you should have injector pulse because they run off the same signal. Quote Link to comment Share on other sites More sharing options...
viasloth Posted January 10, 2012 Author Share Posted January 10, 2012 Ok so I don't know what else to do. I've swapped ECUS, AFMS, Injectors, Fuel Pressure Regulator, Fuel Pump and it still does not want to work. Ive tested everything and it all seems to get power and signal from the ECU but car still does not want to run. Any other ideas? because this weekend I will be starting the process of pulling everything I don't need for carbs off. Quote Link to comment Share on other sites More sharing options...
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