300 problem
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Freshman User
Joined: Feb 2003
Posts: 41
Likes: 0
300 problem
Well i have a f-150 with an efi 300. the problem is it runs rich when it throttles down. It shoots black smoke and unburned fuel from the tailpipe, it gets horrid gas milage, and runs like crap overall. I just replaced the o2 sensor, and it still shoots unburned fuell and black smoke out the tailpipe, it runs better i think,but its my uncles truck and i need to get it fixed for him. What else could cause the engine to run like this? I was thnking the injecters are bad and just dumping fuel in when i let off the gas. But other than that im drawing a blank.
all alone in the world
Joined: Feb 2002
Posts: 2,038
Likes: 1
From: oklahoma
sounds like a bad fuel pressure regulator. the stinking thing is vacumn operated, so you can guess what happens when it goes bad. i would also check all the vacumn lines, a cracked line or one that has fallen off will make them run rich sometimes.
Senior User
Joined: Jul 2003
Posts: 166
Likes: 1
From: Aviano AB, Italy
it should be right on the fuel rail little round thing with a vacuum line running to it. usually an easy way to tell if it is bad is to pull the vacuum line off of it and see if any fuel dumps out when you do it if so then definitely replace it. if not then I dunno
