Hi newbie here, Have a 1999 f250 5.4 liter, was sitting for about a month as I don"t use it much, Started stumbling on accelration and missing, had this problem before and a new tank of gas corrected it. This time no so, spark plug blew out of head, did fix with heli coil and decided to tune up, new plugs, coils , fuel injectors. Did the passenger side where plug blew out, changed plugs coils and fuel injectors and test ran it all was fine. Did drivers side but installed fuel rail missing last injector close to fire wall. Tried to start and noticed gas leaking , corrected problem and restarted. Now truck idles fairly good when cold but runs way too rich with black smoke coming out of tailpipe. Also it stallls after a while,seems to be loading up with too much fuel, raising rpms clears it up a bit then it stalls.No check engine light either,sort of stumped, thinking of reinstalling old injectors on driver side of engine as this is when problem started, other than that I'm at a loss as to how to proceed. Any suggestions??????????

 

Have you tested fuel pressure? Could be pump or filter. You can rent a pressure tester at Auto Zone if you don’t have one. Some of the 5.4s need an adapter for the tester.

 

Suspect this, but not sure without seeing data stream info and fuel trim on scan tool.

The injector down at the end many times get all the junk and can clog up. If this happens, the oxygen sensor tells PCM system is lean and PCM tries to correct by adding fuel and result is over rich condition..

 

It sounds like the problem is caused by the new fuel injectors on the driver’s side. Black smoke, rich running, and stalling usually indicate too much fuel. Reinstalling the old injectors on that side is a good first step—if the engine runs properly afterward, the new injectors may be faulty, installed incorrectly, or incompatible. Also double-check that all injectors are fully seated, the fuel rail is secured, and there are no leaks or vacuum issues. Checking fuel pressure to ensure it’s within spec is important as well. Fixing these should resolve the rich running and stalling.