Don't nix up starting and running.  If it runs well, with no weak cylinders, that's a sign that the injectors are fine.

The cold start valve and the ECU are involved in starting, along with residual fuel pressure in the fuel rail.  Leaking FPR's are a common cause of hard starting.  Today's aftermarket FPR's are of poor quality and tend to bleed off pressure pretty quickly.  Have you watched the pressure bleed down after shut-down?  Generally, the rail should maintain about 15 psi for hours.  If pressure leaks down to zero within an hour you'll have hard starting, since the rail will be empty of fuel when you restart.

13 minutes ago, Zed Head said:

Don't nix up starting and running.  If it runs well, with no weak cylinders, that's a sign that the injectors are fine.

The cold start valve and the ECU are involved in starting, along with residual fuel pressure in the fuel rail.  Leaking FPR's are a common cause of hard starting.  Today's aftermarket FPR's are of poor quality and tend to bleed off pressure pretty quickly.  Have you watched the pressure bleed down after shut-down?  Generally, the rail should maintain about 15 psi for hours.  If pressure leaks down to zero within an hour you'll have hard starting, since the rail will be empty of fuel when you restart.

Regarding residual fuel pressure, it takes all night to get down to 15 or 20 and another day(ish) to get down to full zero.  I tested the empty rail possibility when I still had the pressure gauge still on.  I pulled the oil pressure switch connector, put the car in on, and once the fuel pressure said ~40ish I tried to start the car and there was no change to how it starts if I wait for a few days then crank it.

Regarding the cold start valve, I jury-rigged a switch in the car so I can manually trigger it during cranking - when I turn that switch on, the car starts immediately (like it used to).  But if that isn't used, it's a real struggle.  I'm not sure if that information helps, but I figured it couldn't hurt to pass it along.

I'm not sure what real struggle means.  But I did remove the CSV from my engine when I switched to a 280ZX fuel rail (the 280ZX CSV is in a different location) and it was harder to start in the cold weather.  My remedy was to hit Start for a few engine revolutions, then wait about 15 seconds for the liquid fuel that had been squirted to vaporize.

Nissan put the CSV on for a reason.  Hard cold starting.  Maybe you should just reconnect it.

Absolutely no expert but I can’t imagine it would unless your luck is bad and got water in the fuel from the gas station. That’s why I recommended SeaFoam.

5 hours ago, Zed Head said:

I'm not sure what real struggle means.  But I did remove the CSV from my engine when I switched to a 280ZX fuel rail (the 280ZX CSV is in a different location) and it was harder to start in the cold weather.  My remedy was to hit Start for a few engine revolutions, then wait about 15 seconds for the liquid fuel that had been squirted to vaporize.

Nissan put the CSV on for a reason.  Hard cold starting.  Maybe you should just reconnect it.

Gotcha, I'll keep using the switch to trigger it then.  We'll see in the spring when it warms up if it's still feisty haha.

3 hours ago, Yarb said:

Absolutely no expert but I can’t imagine it would unless your luck is bad and got water in the fuel from the gas station. That’s why I recommended SeaFoam.

gotcha, fair enough

19 hours ago, Zed Head said:

I'm not sure what real struggle means.  But I did remove the CSV from my engine when I switched to a 280ZX fuel rail (the 280ZX CSV is in a different location) and it was harder to start in the cold weather.  My remedy was to hit Start for a few engine revolutions, then wait about 15 seconds for the liquid fuel that had been squirted to vaporize.

Nissan put the CSV on for a reason.  Hard cold starting.  Maybe you should just reconnect it.

I made a video of the hard start here which should help.  It did start quicker yesterday (this video) but usually the skip at 0:16 lasts a lot longer.  This is without manually triggering the CSV.

Edited February 17Feb 17 by chaseincats
added extra information

"Cold" is only cold in engine operating temperature terms.  A nice day will still use the CSV.

 

 

 

Edited February 17Feb 17 by Zed Head

13 minutes ago, Zed Head said:

"Cold" is only cold in engine operating temperature terms.  A nice day will still use the CSV.

In the past when not using the CSV it hasn't done that skip/stumble noise it does now in the video at 0:16

Edited February 17Feb 17 by chaseincats

Maybe you had a leaking fuel injector.  An inadvertent cold start enrichment.

3 minutes ago, Zed Head said:

Maybe you had a leaking fuel injector.  An inadvertent cold start enrichment.

It's the opposite where if I manually trigger the CSV it starts right up, but if I don't use it, it stumbles like it's not getting enough fuel

Sounds like normal behavior.  Right?