1985 Nissan 300ZX Cold starting

Tiny
ROB WEBSTER
  • MEMBER
  • 1985 NISSAN 300ZX
  • 6 CYL
  • 2WD
  • MANUAL
  • 200,000 MILES
I have a 1985 300zx. I have been having problems with starting the car when cold. It has been giving me trouble for years. I just did a motor swap last week. A newer 3L V6. Swaped the long block. Kept original intake and exhaust. Now my starting problem is worse. Once the engine is warm it runs excellent. Takes a act of god to get it to start when cold. Turns over just dosn't fire on all six.
Tuesday, August 12th, 2008 AT 11:36 AM

3 Replies

Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
Check the fuel pressure and comeback with your readings or you can try below and see what happens when it cranks and refuses to start

Get a carb cleaner and spray into the carb or the throttle body on an EFI. Did it start and die? If not disconnect a sparkplug wire or 2 and ground it to the engine -have helper crank engine over-do you have a snapping blue spark? If so-you have a fuel problem, check the fuel pressure to rule out the fuel pump/pressure regulator and listen to the injector/s are they pulsing or hook up a noid light. No snapping blue spark continue to troubleshoot the ignition system-power input to the coil/coil, distributor pick-up coil, ignition control module, cam and crank sensors-
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Tuesday, August 12th, 2008 AT 11:55 AM
Tiny
ROB WEBSTER
  • MEMBER
  • 2 POSTS
Fuel preasure is good what is a noid light? I did not see crank or cam sensors. I dont think it has them. Changed motors stripped down to the long block did not see any sensors. I will check for blue spark. Fuel preasure was over 15 psi
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Tuesday, August 12th, 2008 AT 12:47 PM
Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
Fuel pressure at idle should be 30psi and when accelerator is depressed should be 37psi

Noid light is what you use to check if the injector/s are pulsing-meaning getting power on and off

Let me know about the snapping blue spark-nonexistence it will never start
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Tuesday, August 12th, 2008 AT 4:34 PM

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