dj paul Posted April 4, 2007 Share Posted April 4, 2007 hey guys. The problem i have with starting is coming back. I replaced the cold start injector and it fired right up for some time. Then, in about the past week, it acts like it is disconnected. You have to crank and pump the gas pedal a bunch of times and then it starts up. Sometimes you have to do this so many times and for so long (about 10 minutes of on and off cranking) that the battery wears itself out before it starts up which was almost the case leaving work last night (boy i was glad it started) Also, occasionally even when the car is warm, it will want to die at idle and you have to rev the motor up. It will sound/feel like its running on 5 cylinders and backfire a few times. then it runs great once you put a load on it and get it above 3k rpm. This morning, i couldnt even get it to start up even after the 10 minute crank/pump routine so i had to get a ride with the dad to class. Anyways, im just wondering if anyone has any idea of what this could be. When i get home today im going to check the resistance of all the injectors and the cold start valve. Im also going to replace the pressure regulator since i have a known working one. Any other ideas guys? this sucks really bad since this is my daily driver. Quote Link to comment Share on other sites More sharing options...
DCZ Posted April 4, 2007 Share Posted April 4, 2007 I don't have the answer for you but I can tell you this: Pumping the gas pedal does nothing other than opening and closing the throttle valve. There is no "choke" or fuel enrichment due to pumping the pedal. You need 3 things: air, fuel, spark. (OK, timing, but that is not really a "thing" Verify that you have all three. Your symptoms can be caused by a weak spark, too little fuel or too much fuel, or a really clogged air filter. Try pulling a spark plug when you are having trouble starting and see if it is coated with fuel. Connect the plug to the plug wire and rest it on your valve cover and see if you have a good spark while cranking. Also clean every single electrical connector under the hood. Corrosion / crud buildup can really cause havoc. Good Luck! Quote Link to comment Share on other sites More sharing options...
naviathan Posted April 4, 2007 Share Posted April 4, 2007 Sounds like your fuel pump is dying. Do a fuel pressure test. Quote Link to comment Share on other sites More sharing options...
dj paul Posted April 4, 2007 Author Share Posted April 4, 2007 k thanks guys, i have cleaned all the connections thouroughly about a week ago. it seems like if i mess with that idle air screw and open it up a lot it starts up sooner. Pretty soon im switching over to the non webed non egr manifold and using the perfect injectors out of the 12 that i have. I do need to get a fuel pressure tester. Im about to order one of those rising fuel rate regulators with a gauge on it, because theyre the same price as a simple gauge tester itself. I hope its not the fuel pump because thats the only spare part i dont have an extra of. any more ideas? Quote Link to comment Share on other sites More sharing options...
naviathan Posted April 4, 2007 Share Posted April 4, 2007 Hope or not, check your fuel pressure because if it's dying out while running then you're loosing fuel pressure more than likely. Have you checked your plugs to see if you're running rich/lean? Quote Link to comment Share on other sites More sharing options...
mario_82_ZXT Posted April 4, 2007 Share Posted April 4, 2007 I had this problem a few weeks ago and it ended up being a defective cell in my new battery. Sometimes it would crank over perfectly and others it would act like it wasn't getting fuel. I think the voltage might have been dropping enough that some things weren't working (ECU or injectors... not sure which). Mario Quote Link to comment Share on other sites More sharing options...
lifegrddude Posted April 4, 2007 Share Posted April 4, 2007 Check for vacuum leaks as well. When my Z had a leak (granted it's a turbo, but it might be the same problem) I had to feather the throttle to keep it from stalling. Turned out I had a hairline crack in one of the vacuum lines. Quote Link to comment Share on other sites More sharing options...
mom'sZ Posted April 5, 2007 Share Posted April 5, 2007 What year car is this? Is it fuel injection and is the FI stock? If it says somewhere and I'm blind.... sorry Quote Link to comment Share on other sites More sharing options...
VinhZXT Posted April 5, 2007 Share Posted April 5, 2007 I had the exact problem with my 79 280ZX and the problem was the AFM. It was running way too rich. Tighten up the spring in the AFM fixed the problem on my car. Check your rear bumper to see whether you have a lot of black smode deposit on the bumper? If so then your car had the same problem as mine. GL. Quote Link to comment Share on other sites More sharing options...
dj paul Posted April 5, 2007 Author Share Posted April 5, 2007 alright thanks guys. yes its an 80 280zx stock FI unchanged. Found a leaky injector yesterday so im just going to go ahead and put my other manifold and headers on (non webbed/egr). Just in case i cant find it, how the hell do you replace the hoses on the injectors? i cant figure it out but i didnt look at it that long. You know how that little metal crimp thing holds the hose on? do you need a special tool to take this off/put new one on? i want to go ahead and put all new hoses on here since all are original. Quote Link to comment Share on other sites More sharing options...
naviathan Posted April 5, 2007 Share Posted April 5, 2007 Nope, that's covered in the forums extensively. I used an exacto knife and cut the hose as far down into the crimp as I could then pulled it out with a pair of needle nose pliers. Throw away the metal piece and use fuel injection hose clamps instead. Don't use the regular hose clamps with the slots, use actual FI clamps. They're solid like the factory ones. Quote Link to comment Share on other sites More sharing options...
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