I have a 1986 300 ZX non-turbo that will not start. I have had it since July 2017. It has been running fine until 2 weekends ago. Upon starting it was running really rough with black smoke coming out of the exhaust. I am assumed it was running rich. After I turned it off it would not start. I waited several hours tried again and it started, still running rough. On the ride home it suddenly started running normal. Drove it last week, went to work Friday and it hasn't started since. I ran diagnosis on ECU. It gave me codes 12, 13, 21, and 41. I replaced the Air Flow Sensor last night. It first tried to start, then nothing. It is now showing 23, 31, and 41. It has plenty of fuel. You can smell it. It has spark at the distributor. Thanks for your input.

 

Locate your air regulator and check the operation of the 2 solenoids it houses.One is idle-up reg, important for holding idle. You test them by removing, applying a charge and listening for the little click of the solenoid inside. Hard to find replacements unless you buy the whole regulator from a recycler. They are available Check out your FSM XenonZcar.com Z31 1984-1989 300zx Reference and maybe Car-Part.com--Used Auto Parts Market for a nearby recycler. Report back, please. Gracias.

 

By your description its flooded after 5 sec FI starts to overfuel
best to pull the plugs carefully dry them or replace ,careful with spark ,coil discon. Crank the fuel out the sp holes ,I usually discon the injector conections start on carb spray if needed

 

Thanks for your input. I will be looking at it this weekend. I will let you know what turns out.