Cold sputter, hard start once warm???

[Ac12992]

Hello My car is a 1991 240sx s13 ka24de automatic(yes its coming out soon), when i start it up it sputters until it warms up the idle still goes up like normal on start but the exhaust put puts until you take off and get warm. Once warm if you shut it off and wait ten minutes it doesnt wanna start back up i gotta hold pedal to the floor and after 7-10 cranks it fires, where cold its one. ive probed these forums for a year now and learned soooo much you guys are awesome. First time 240 owner and so far i love the car. it made me like to drive, its sooo damn fast. Fresh Build i did with a friend all lightweight cnc Felpro gaskets topto bottom ready for boost after tranns swap.


Things changed/new parts
New o2 sensor-old one did the same thing
new made in usa fuel pump - old one did the same(old was a 255 i put in, new is a 340)
new coolant temp sensor- old one did the same
adjusted tps sensor with multimeter
cleaned maf
300zx fuel filter
New plugs and 8mm wires
timing checked
no vaccume leaks it holds pressure
regrounded(added two), and cleaned every electrical connector in the bay and the fuel pump housing


Thoughts suggestions? Frustration is setting in haha

[PapaSmurf2k3]

Welcome NICO you lurking creeper!
It sounds like you've replaced all the usual suspects so far. How did your plugs look when you removed them? Was one all black and carboned up? Holding the pedal to the floor during cranking should cut the fuel during cranking (and assists with clearing the cylinders). It almost sounds like you either have leaky fuel injectors, or a bad/sticking idle air control valve, not giving enough air.

[PapaSmurf2k3]

Also, if you pull the fuel pump fuse before you start cranking (after shutdown when hot), does it eventually start?

[Ac12992]

The plugs looked kinda lean..but not fried dry haha..and i suspected a leaking injector but my buddy doesnt think so...they are definately used but didnt appear damaged when i had the rail off fixing the rubber boots. And im glad to see your name helping me, thanks brother.

[PapaSmurf2k3]

Ok. We need to determine if you're getting too much fuel, not enough fuel, or if fuel isn't a factor in this problem. I'd proceed with the easiest thing first and pulling the fuel pump fuse prior to cranking (and then plugging it back in once the car dies or doesn't start). If that doesn't help, pull a vacuum line and pour some fuel down there. If you're too lean for starting, this should help it to fire right up.
Of course, if it isn't a fuel problem, neither of these will help and we will go back to the drawing board.

[Ac12992]

ok so i again changed the fuel filter, the one i put it in before was installed prior to the rebuild and the car had been sitting when i got it. so im guessing it became clogged up after maybe seafoam cleaned stuff from the tank??...who knows. anyway the problem seems to be fixed now. true test will be after i drive it tomorrow. sorry for the delay. ill keep you informed.

the car was filthy dirty when i got it, factory white paint looked black from sitting under a tree..no rust(indiana car owned by 75 year old man ), clearcoat is there, and the transmission had always been factory serviced with receipts, new tires, 200kmiles 1000$. three washes rubbing compound and several coats of wax the white will blind you in the sun....simple tuneup anyone should do to sitting car, back to burnin rubber. anyway it wouldnt suprise me if the tank had dirty stuff in it.

[Ac12992]

hatch rear sunroof :]