fuel pump maybe?
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fuel pump maybe?
Hey fellas, its cold where I live in the winter and my 2003 5.4 has been firing up and warming itself up perfectly all winter long. I recently went a filled the tank with premium and the very next morning my issue started. Ill hit the key, she fires right up then the idle slows down and depending on how cold, die. Fires right back up, idle kicks down and gets lopey and rough for a few seconds then idle picks up and slowly decreases with warm up as it should. On the real cold mornings it will die twice before keeping the idle up and running. ECT usually reads 30 to 40 degrees so I know that sensor is good. When warm everything is fine and no driving issues although since this started I noticed a fuel economy drop, Im running the Gryphon. Considering this started with the fuel up Im guessing a fuel problem. I promptly replaced the IAC and reprogrammed the cold start, and new fuel filter. I havent checked fuel pressure but Im thinking fuel pump maybe? I appreciate it in advance!
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Dont think its the fuel pump ..my 99 F 150 went bad this past fall....it would not even start..had to turn key off and on several time..check valve in fuel pump was bad..changed the whole pump......my truck has the 5.4 engine and couple of years ago it did something smiliar to yours and was the IAC control...i think that is what the mechanic said....also check the fuel filter as it could clog up some....and cause fuel issues....you can get a fuel pressure gauge and go to fuel rail and mine had valve stem ...and check fuel pressure to be sure..mine was on passenger side!
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Ok well I did already replace the fuel filter and IAC. Tested the fuel pressure tonight, its was at 40psi with key on, not running. 32 psi at idle and 40 psi at WOT. Fuel pressure looks good. Any ideas out there?
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So I started thinking yesterday maybe I had gotten some water with my fuel that day and it was freezing at night. I got a full tank of regular, reprogrammed the Gryphon for reg. fuel, and dumped 2 cans of HEET in the tank and ran it for a while. I just went out and started her up and its perfect! Not sure if it was water or the programmer. I just remembered that a long time ago I reprogrammed and fired her up, she died instantly. I reprogrammed the same tune again and everything was fine, so maybe thats the case here. At any rate... theres my story
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