2004 Hyundai Elantra Hyandai Fuel delivery issue

What is the vehicle doing? Did you replace the fuel filter? Is the pressure to the engine within the manufacturer's specs?

It still seems fueled starved after sitting over night.The fuel filter is part of the pump assembly I replaced. I have not had a pressure reading done.

I assumed the pressure would be good after the pump and all were replaced.

If it seems to happen after sitting overnight, that leads me to believe the pressure is dropping off and it is taking the pump time to get things built back up.

Try this in the AM. Cycle the key from of to on 3 times. Each time, wait about 3 seconds before returning to the off position. On the 3rd time, start the engine. Is there any difference?

Also, here is a video for checking fuel pump pressure, the pressure regulator, and drop off. Let me know if it helps.

https://www.2carpros.com/articles/fuel-pump-pressure-and-regulator-test-video-all-cars

That is what I have been doing each morning. It eventually starts after listening to the fuel pump cycle over and over in the morning. Then it starts and will continue to start the rest of the day until left over night.

I did the Cycle the key from of to on 3 times. Each time, wait about 3 seconds before returning to the off position. On the 3rd time, start the engine.

Then it started...any idea on why this is happening?

Okay, if that helped it start, then there is something allowing fuel pump pressure to drop. I need you to check fuel pump pressure and then see how quickly the pressure drops off when you turn the key off.

If it drops quickly, you could have a leaking injector, a leak in the fuel system... I forgot to ask, but is the check engine light on?

No "Check Engine" light...

Okay, that tells me that it isn't an issue with a sensor. Let me know what you find with fuel pressure drop off.