The engine is shooting too much fuel and runs rough until warmed up

Hi,

Have you checked fuel pressure? There could be an issue with the fuel pressure regulator.

Do me a favor. On top of the fuel rail is the regulator (see pic 1 below). There is a vacuum hose running to it. Remove the vacuum hose and check to see if there is any evidence of gas in the hose. Also, have a helper start the engine and confirm there is a vacuum to the hose.

If there is, if you have a vacuum pump, see if it holds a vacuum.

If that checks good, then I do recommend checking the fuel pressure. Here is a link that explains how it's done:

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

Also, if you have a live data scan tool, check the signal from the ECT (engine coolant temperature) sensor. The ECM uses this signal to determine the air/fuel mixture needed to run the engine at a certain temperature. If it indicates it is -40 F and the outside temperature is 60F, the fuel mixture will be extremely rich.

Do these things and let me know what you find. Also, if you have already done this or retrieved diagnostic trouble codes, let me know that as well.

Take care,

Joe

See pic below.