I have a 2003 Nissan Xterra, and have been having starting issues for while. Everybody who does a starting diagnostic test says everything is ok and working. Over the past 18 months, I have gotten new battery (charge is fine), replaced starter ( fine), distributor cap (wires, sparkplugs, cap, also fine.) Alternator has tested fine also, have not replaced this yet. The delay seems to be getting slightly longer, but once kicks in car starts fine. I have put too much money into this already to fix problem that has not gone away. Something is wrong and nobody has a clue, anybody have any suggestions or help would be very helpful. Side note, no problems with engine, just takes a few seconds to start.
I would have the fuel pump pressure tested and have the fuel filter changed if you haven’t done so already. Sounds like a fuel related problem to me.
Sounds like the fuel pump is struggling on the initial key turn. Or a clogged fuel filter, restricting fuel flow on startup. Or a bad fuel pressure regulator. See if you can get a fuel pressure gauge and test fuel flow.