Hi,
The idea that you need to press the throttle to the floor tells me it is flooding. By pressing the throttle to the floor, it shuts off the fuel injectors to clear a flooded engine. Additionally, the black smoke indicates the same thing, too much fuel.
Since the fuel pressure is within specification, I need you to check fuel pressure drop off when the key is turned off. This way we can determine if you have leaking fuel injectors causing the engine to flood.
I attached the directions below for testing fuel pressure drop off (leak down). Also, there is a fuel rail pressure sensor that may be causing issues. Have you scanned for diagnostic trouble codes?
Let me know.
Joe
See pic below.
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Wednesday, March 13th, 2024 AT 7:24 PM