big_birdf150

Hey guys I have a 2004 f150 NBS with the 5.4 3V motor in it. On the driver-side of the fuel rail near the front there is an electrical black box that has a harness connected to it and it is bolted directly to the fuel rail itself. My question is mine has a vacuum line fitting coming out towards the front I believe and im wondering where that vacuum line connects to. I am still wiring and connecting all my vacuum lines so I want to make sure I'm connecting it to the right ports. I have searched forums and Haynes manuals to no avail, even to find out what that black box is for would be a tremendous help. Thank you all in advance.

F150Torqued

I have a 2004 F150 w/ 5.4L 3v engine also. That black box on the driver's side fuel rail is the "Fuel Rail Pressure Sensor". Mine also has an orange vacuum line that runs around the rear of the intake manifold and forward about half way up the bank 1 fuel rail - where it is terminated with a "plug". It connects to nothing.


My OBDII Torque App has a PID (Parameter ID) designated "Fuel Rail Pressure (relative to manifold vacuum)" that BTW produces no data on my vehicle. I wonder if that vacuum line were connected to a vacuum port....... if it wouldn't "shift" the Fuel Rail Pressure reading it is producing to the PCM based upon vacuum applied? But, I would think if the PCM wasn't expecting such a "relative" or "shifted" reading (based upon manifold vacuum) as opposed to a "fixed" reading, it might confuse the program into mal-adjusting fuel trim or some other bizzare effect. IMHO, yours, like mine, should go nowhere (just be plugged).


**** Big_birdF150, I TOLD YOU WRONG!!!!!. My apologies. It so happens I changed out the intake manifold on my 04 F150 TODAY seeking to find and remove a vacuum leak.......... Now, I now A LOT more (first hand) than I did when I posted the above response. Perhaps sorta typical for many wannabe mechanics you find on these forums.


----------- The RIGHT ANSWER-----
My 04 F150 is a Lariat 7500 GVW version. I find it best often to ask for parts for a F250 to get the right parts. Such was the case with the replacement manifold (plastic seemed to have a crack) - because spraying starting fluid UNDER the plastic manifold - above the valley - would make the O2 sensor graph readings on my Torque OBDII APP go crazy.


My original answer was partly correct. There is an orange plastic vacuum line that runs from the Fuel Rail Pressure Sensor on the Bank 2 fuel rail around the rear of the intake manifold -- behind the TB on the passenger side, --- WHERE it goes DOWN to a dual vacuum line female connector that connects to a vacuum port on the bottom of the intake manifold's "vacuum resonance chamber" *1. The port is below the "IMRC" actuator (Intake Manifold Runner Control actuator)*2. The other line comes back up and forward along bank one about 1/2 way where it is "plugged" - I suppose for instances where there might be a separate fuel rail pressure sensor for Bank 1.


*1 - The plastic intake manifold on this engine is rather bizzare. It has a huge resonance chamber that fills the entire valley between the heads. The intake tubes are about 12 - 14 inches long running from the bottom of the vacuum resonance chamber up and over to each cylinder head intake port. (IMHO, this it to create sort of a RAM induction effect!).


*2 - Right above each (of the 8) intake ports - immediately below the fuel injectors - is a butterfly (similar to the one in the TB). These butterflies function as what I used to be familiar with from old days as a "constant velocity" carburetor, and are connected by a shaft running all the way to the back of each side of the manifold. This is called the "Intake Manifold Runner Control", and the "electrical actuator" IMRC actuator is mounted on the rear of the intake manifold - literally right against the firewall!!!!! . The electrically actuated IMRC valve (0-5v from the PCM) opens and closes these butterflies to better maintain a constant velocity of airflow into the intake valve chamber and better atomize the fuel injector spray.


Hope mine all works after changing it out ---- and I hope this first hand description helps.

F150Torqued

@ Big_birdf150,


I wish I had found the following link before I tried to answer your question on this link the first time. I wish MORE that I had found this link before I changed the intake manifold out on my truck. Both would have turned out better.


http://www.ford-trucks.com/forums/10...any-ideas.html


Best of luck.

Katness

I am desperately needing guidance...just bought this truck used. It had been needing a coil pack and new plugs for sometime it seemed. I changed them out and luckily my small hands were able to reach into the tight areas without having to really move or remove anything. Unfortunately though, as just a mechanically inclined not mechanic - this little lady is stuck...I don't know what the parts are called to look up the new issue.
I can tell you that I DID NOT reset the adaptive memory before I decided to hop my *** in and try to start it. DUMB! The good girl tried to start but stalled after about 3 seconds of chugg a lugging. Noticed immediately a strong gas smell - looked under hood again, then tried to start once more. Saw that the area on driver side of engine where the "throttle body" (I believe) is, and what I think to be one of the "fuel rails" is located...gas spraying EVERYWHERE!
There was an O-Ring in this area that I removed and cleaned - put back in - maybe upside down...not sure. Now, I am scared to do much more without guidance. I am about to go back down to her and try resetting the memory first...then I will check back for responses. I am a single chicka who needs her truck to haul lumber and materials for a remodeling career I have been training for the last few years. This truck is make it or break it status for me....please help.

techrep

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Katness

It's turned out to be what I believe to be the fuel pressure sensor....?