1976 280z hard start and rough idle
I have a 1976 280z and I am having hard start and rough idle where the car keeps dieing on me. When starting the car it wont start right away. When I crank the engine one or two cylinders fire but then it stops. I have to do this several times (5-10 times) until it will start and fire for a few seconds before it dies. The rpms will get up to 500 and bounce around and fall down until it dies. This will happen a few times and will eventually get up to 1000 rpm, run for a little, and die. After about 5 to 10 minutes it will start to idle rough at 1000 rpm and stay idling. I can then gingerly rev it up to 2000 rpm but if I rev it too fast the engine will hesitate and back fire out the intake until it breaks past 1500 rpm. The weird thing is at 1500 rpm and up it runs smoothly with no hesitation. After 5 to 10 minutes the engine gets up to about 1200 rpm at idle and idles pretty good. The hesitation goes away and I can quickly rev the engine with no back firing from 1200 rpm to 4000 rpm. At this point I can turn off the car and start it again no problem. I think the problem is the car wont start unless it is warmed up. I figure that cranking the car over and over letting one to two cylinders fire eventually warms up the car to where it will kind of run. It eventually fully warms up and idles pretty steady and revs up well. Is there something that would greatly be affected by a cold engine? I'm not sure if my cold start valve is operating right. Could that cause this? I feel like that there might be something more too it. I plan on checking for a signal in the connector to the cold start valve and trying to manually hook it up to the battery to see if it will spray anything.
A few notes:
I have checked for vacuum leaks with brake clean and there are not any. I have cleaned all 6 injectors and I have a new airtex fuel pump and fram fuel filter. New spark plugs and new battery. One issue I do have is the fuel pimp will not turn on in the on position but I have hooked it up directly to the battery so it is not a priming problem.