KaiserVision

I know there was an old thread for this issue, but I didn't think it would be ok to revive a thread from 2010. Anyways with that being said.

1985 300Zx Non Turbo

My car starts perfectly fine when cold, but after driving around and shutting the car off, within I would say about 2 minutes or longer of it sitting, the engine has a very very hard time starting. This issue has been apparent since I have bought the car, so it's not something that came up after a recent service or anything.

Recently I have installed all new parts for the cooling system, new timing belt, new battery, new starter etc.

The car will only run rough when starting hot, it will attempt to start, but chokes out after a few seconds, after revving the engine to about 3700 RPM once it finally tries to start, it sounds like it's not running on all cylinders.

It feels like it's starving for fuel, but i'm not 100% sure. it's driving me crazy.

NismoPick

Have you checked the ECU diagnostic codes?

86tcoupe

Thats called Hot soak condition
Does your ride have the blower and duct work to the injectors ? Got it full of coolant ,radiator cooling good ?

rogerz

try unplugging the O2 sensor. if the problem goes away - bad sensor. Another heat related item would be the chts being faulty. Read the fsm free download from Xenon

KaiserVision

I ordered the CHTS it should be here by the end of the week, hopefully once that is replaced this issue will be fixed. I've done a lot of research and still cannot understand why the CHTS would cause an issue like this, but apparently a lot of people claim this is the root cause.

Can anyone back that statement up? or has anyone heard of that before?

NismoPick

Did you read / heed all of the above suggestions?
CHTS = Cylinder Head Temperature Sensor. Read all about it in the free FSM: Index of /FSM/300zx/1985

It's faster and cheaper to do tests, rather than throw parts at it.

Mike Kwon

it seems like bad crank angle sensor....

tnewcamp

85 turbo no hot start after 10 min. The problem with my z was rusty gas tank the fine rust goes right through the filter and does not let injectors close lets fuel seep into engine and is flooded use of full throttle when starting will help a fix would be seal inside of tank with a ebay sold tank sealer or a quick fix would be a neodymium magnet on your fuel filter i used a 2in by 1/2in magnet. the metal fuel filter with magnet stuck on it will catch most of the rust but not all it was a big help for me.

Barneszy's Z

I bought an 85 NA that had a similar issue. It would take 4-5 turn overs to start on a cold start. Ran fine until I would shut it down and restart after a brief stop (ie, getting gas). After the restart it would have low power, almost like the engine was bogging down. Wasnt running clean. After driving down the road a for a bit it would start to clear up. I took the car to Nissan (sales manager a good friend of mine) to replace plugs and just check for any other issues since I bought the car. He recommended that I replace plugs, wires, cap etc with OEM parts and so I did. Car starts on first kick now during a cold start, has more power and runs perfect after restart.

rabidewok

Its going to be your fuel pressure regulator modulator