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A little help on possible fuel issue, sometimes it will not start until much later.

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  • A little help on possible fuel issue, sometimes it will not start until much later.

    The 87 NA 2+2 I picked up and have been working on needed a new transmission. I got it out of the shop last week after having the tranny rebuilt. I drained the old fuel and filled it up and all was fine until yesterday. I went to run to town and as it has normally started I thought nothing of it. I turned the ignition and it briefly started like it didn't get enough fuel. So I cranked it again and this time it would not start, just cranked over and over. I checked it for spark and that was fine. I left it alone and it started fine this morning. After work today it did it again at my GF's house. I had to leave it there since it was dark and only about 2 hours ago. I did pick up a new fuel filter but did not install it yet. Can someone share some experience with me on this? Any idea's or experience would be appreciated.

  • #2
    are you sure it has proper spark? sometimes the ignition transister goes out and you end up not getting fire to the coil. just a possibility if you can rule out fuel. you should check fuel pressure at the manifold or you could even disconnect the fuel line at the fuel filter and put it down into a bucket and if fuel shoots out at that point when you start, you'll at least know that fuel is getting from the tank up to the engine bay. but before you try that, make sure your fuel pump is kicking on. on the 87, when you turn the key, you should hear it. if you don't, then you'll need to figure out why its not activating. and I beleive, at least on my 87, the pump kicks on for about 5 seconds and then turns off, however I may have that confused with the 83 280zx. but you should be hearing it when you go to start the car.

    Bon

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    • MKS71
      MKS71 commented
      Editing a comment
      Thanks for the reply, both times that this has happened, Sunday and yesterday I would turn the key and it would fire up but just like a old car it would not stay running. Thats where if I try again it doesn't start. Both times though long periods of waiting then attempting to start it worked. This morning it started right up and ran fine. I will replace the fuel filter today and go from there.

    • dbruce
      dbruce commented
      Editing a comment
      My 85 had been sitting for 2 years and replacing the fuel filter seemed to make a big difference . I wish I had a pressure gauge to see the difference . I needed to replace a bit of fuel hose to do the job . also try adding Magic mystery oil in the fuel (cleans and lubricates the injectors)..

      also the MAF connector maybe dirty ... spray electrical cleaner on all the connections
      Last edited by dbruce; 10-16-2018, 01:34 PM.

  • #3
    I hate chasing odd things down. I’m trying to figure out a scenario now and it’s driving me crazy. Did you put the Ecu in diagnostic. Mode and check for codes?
    Jeff
    71 240z

    80 280zx 10th Anniversary

    88 300zx Turbo, 89 300zx Turbo

    Datsun Jeff

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    • #4
      I have not done that yet. This car did sit for over a year and I'm sure it's something simple.

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      • #5
        I put the fuel filter on and it started fine so I drove it home. That was about 2 hours ago. I just went to start it again and did the same thing, it got the initial start but did not stay running. I tried for another minute or two and then stopped. I took the fuel line off and there was no pressure at all. I put the hose in a bottle, turned the key and it filled up the water bottle quickly. I put the hose back on and it fired right up. Could this be a fuel pump issue?

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        • #6
          Bon, I have a hard time hearing if the pump is running due to the electric antenna.

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          • #7
            I am at my girlfriends house and it did this again, not staying running. I did experience something different though. I took the fuel line off right before it gets to the fuel rail and it had a lot of pressure on the engine side and sprayed quite a bit. I turned the key and fuel came out of the tank side and I put it back on and it fired right up and stayed running. I am at a loss. HELP! Please

            So while driving it home and I was giving it some thought. I am curious as to why there would be back pressure. I am also wondering if the injectors are not doing there job sometimes. If I let off the pressure it will start without a problem.

            Could this be a fuel return line issue?
            Last edited by MKS71; 10-16-2018, 06:26 PM. Reason: More observations

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            • #8
              I just placed an order for a new FPR and I will see if that does it. It was not spewing fuel but I did read a few posts where it was still keeping the car from starting. Hopefully this will take care of it.

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              • #9
                look, i'm having this same kind of issue on my car. but it didn't show up until i converted it from NA to Turbo. you can probably rule out ignition. that being said, there are some other items you should check and by the book in its diagnostic procedures. first thing i recommend is decoding the ECU. find out if things are mal-functioning, then go from there. it sounds to me like you're getting fuel up the the engine manifold. its possible that the FPR is bad, then again... a way to check is to remove the vacuum line that goes to it and then try it. if the diaphram is not functioning, then you may have a problem with fuel at that point. i actually replaced my unit but it didn't help the problem. how cold is it outside when you start the car for the first time? the auxilary air valve could be malfunctioning. you also may have a problem with the idle control valve, or a major vacuum leak(s) somewhere, and last your MAF could be failing. you should remove that and inspect it.

                on my car, it never starts the first time and stays running. it always fires up, but always dies immediately after. i have to start it several times and sometimes keep my foot on the gas to keep it running, however once it finally starts and stays running at idle, it runs great after that. and it stays running. only after i let it sit overnight does it have starting issue again. i think yours is very similar. and it is irritating i know.

                you should be able to hear the pump even with the anntenna noise. what you could do is deactivate it. there may be a fuse for the radio/antenna or maybe a relay that you could disconnect. still, if you're getting gas up to the fuel rail at the proper pressure, then the pump is not your problem. i would not go replace the pump unless you know for sure that it is bad or starting to fail.

                Bon
                Last edited by bonfire79; 10-16-2018, 11:10 PM.

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                • #10
                  It is hot here, 90 degrees or warmer when I have tried to start it. It will start right up right now and it's 70 outside. If mine will not start, it will if I take the fuel line off, relieving the back pressure. At least that is what it did yesterday. I am replacing the FPR only because I have been reading up on it and it's easy and cheap to replace. This is all new, it just did it for the first time on Sunday. I will try what you have suggested.

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                  • #11
                    I replaced the fuel pressure regulator since it was inexpensive and easy to change. That was not my problem and I still do not know what is. I have pulled the ECU codes and it is giving me a 22 which is fuel pump control, it is also giving me a 41 which is the fuel temp sensor. I checked the diag steps in the FSM and it is checking out. It does not appear to be malfunctioning. As the sensor cools off from test driving, the resistance changes to reflect that and it is within specs of the FSM. I also checked the wiring of the FSM to the ECU and it too is within specs. I just paused while typing this, started the car, hooked up my multimeter to the ECM and ground and watched the temp sensor climb.

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                    • #12
                      Not sure if you replaced this yet but it’s cheap and easy. I’m still in shock it was my issue. My distributor cap was bad. The little center plunger would only make contact a little bit.
                      Jeff
                      71 240z

                      80 280zx 10th Anniversary

                      88 300zx Turbo, 89 300zx Turbo

                      Datsun Jeff

                      Comment


                      • #13
                        I'll try it, it appears to be the heat soak issue I've been reading about though. Thanks for the tip

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                        • #14
                          I'll try cheap and easy if there's a chance

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                          • #15
                            get a megasquirt ms3x witrh a 36 to 1 trigger wheel a gm clt and iat sensors and gm ls coils.and you are good to go.Get rid of all the 30 year oid stuff.

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