i have an 81 280zx and its running really rich it starts up but it idles really bad and the plugs are covered with black carbon and it also back fires and blows black smoke when i give it gas any help would be great thanks

 

Probably the O2 sensor.

 

the 02 sensor looks fairly new not saying its not bad but any other suggestions has anyone had these same problems

 

is your timing off?

 

Hey try the fuel air-mixture screw also.

 

i tried the idle screw but still couldnt fix it i played with my timming by turning the distributor still couldnt get it to stop

 

Make sure the wiring for the O2 sensor is in good shape, it could've been damaged by the exhaust. Also, you might want to check for stuck valves. Also, is this a problem that just happened overnight or has the car been this way since you bought it?

 

the o2 wiring looks good do you think it could be the mass air flow meter not working correctly it all started i set my camshaft and crank timming cause it was off about 1 tooth and the car was really sluggish well i fixed that and got it all back together and it revs up to 7k easily before it would be hard to get 5k out of it now its running really rich back firing black smoke black plugs its getting way too much fuel and not enough air

 

Yeah that could be possible. I am wondering if mine is not working right also. My Z runs fine at idle revs fine. But when I go to drive him, it feels like I am pulling a trailer behind him. It is driving me nuts!

 

this sounds pretty close to my problem.. did you ever fix it find out what caused it?

 

I think I concluded that my fuel pressure regulator is bad. But I am not entirely sure either. It could also be my fuel pump. I need to wait and get some money so I can buy a fuel pressure gauge, that will work better for testing my Z out. I am supposed to have 30psi at idle, and it was only reading like 20 or so. But sorry my Z is down until I get caught up, and I have some money again. So I can mess with him again. But I will let you know if I find anything else out, as to help you. Sorry I couldn't be more help. I am learning something about the Z's all the time. Get out the FSM, and soak some more information. Anyway I am thinking about driving pizza delivery for the weekend. Also so I can get myself caught up. And be able to continue my Z project, but until then my Z is grounded!

 

i fixed mine the temp head sensor was unhooked i unhooked it when i was changing the starter out the timming was off aliittle too but mainly it was that sensor my z runs real good now i beat my freinds 79 280zx 3 cars and a moded 88 rx7 3 times in a row about 1 and a half cars and my cars completly stock even the air filter and my tires are old and bald so i couldnt launch above 1500 rpms which sucks hey but i won