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Ford F-Series Fuel Pump/Fuel System



  • have you got any codes ? could be pick up coil .
  • greg7764greg7764 Posts: 1
    I've seen a lot of talk about fuel pump relay chatter but very few answers from people that found their problems. I've checked grounds, inertia switch and connections and wiring. One thing that I did find is when I can catch the relay chattering, I can pull the relay and insert a noid light across the control connections and the noid light continues to flash,(a regular test light would only stay lit) My question is, is the relay controlled only by the ECM or are there other moduals to consider? This is an intermittent problem. Sometimes runs fine but can act up while you're driving or after it's been shut off and won't re start. Thinking I'm headed for a new ECM, but first i'm pulling the bed so that I can check the electrical connections at the tanks. Thanks for any comments.
  • fiver8fiver8 Posts: 1
    edited July 2012
    Hi, I have a 2006 ford f-150 4.6L with hard-starting issues. The truck often cranks longer than usual, which tends to happen after it's been shut off for at least 15 minutes. When the hard-start happens the engine also often "stumbles" into a start and then has a rough idle for 10-30 seconds. After that, it runs and drives fine. I've noticed the truck tends to start better right after it's been shut off and also after it has been sitting overnight (though not always), but usually *not* after it's been shut off for 15-120 minutes (still warm)- in fact this seems to be when the issues are most frequent, at least 15 minutes after vehicle has been shut off.
    I have had the code checked and always says "number 6 cylinder missfire" I have replaced the plug, replaced the coil twice as I evidently broke the first one, replaced the fuel pump, replaced the fuel filter and replaced the fuel rail pressure/temperature regulator. STILL no solution. I am going broke here.
    I have seen where others have had the same problems but I can never seem to see their solutions if any.
    Could someone help me PLEASE?
  • I have a 96 F150. My question is, do the fuel tanks run off each other? In other words, do they empty at the same time?
  • mike9408mike9408 Posts: 74
    No, the tanks do not run at the same time. There is a "fuel switching valve" in the drivers side frame rail right behind the cab. You should be running off of one tank at a time, if your not, there is probably a problem with the valve. Locate the valve then check to be sure power is getting to the valve. If you are getting power to the valve then you probably need a new valve. If you are not getting power to the valve then you may have a blown fuse.
    Good Luck...
  • don't believe so.............isn't that why there's selector switch?
  • z28man1z28man1 Posts: 3
    my 1994 ford f150 has gas trying to come out the front tanks gas cap. i'm using the rear tank because the front tank pump quit working. why is it trying to come oui the front tank cap and how can i stop this from happening?
  • It sounds like your front tank is siphoning fuel from the rear tank. And if the truck is then parked on an incline facing forward or it's an unusually hot day the fuel will force it's way out of the front tank.
    The selector valve is supposed to prevent that siphoning action from occurring.

    just sayin', IMO
  • cheifcheif Posts: 1
    edited September 2012
    My 1993 did the same thing, after replacing a bunch of parts I finally figured out it was the main computer (pcm) that was bad. A rebuilt one from auto zone was $215. It was not hard to change out, had to loosen some screws on the driver's side fender well to get to the computer which is mounted in the firewall. After installing the new computer it ran kind of rough for about 15 minutes but it evened out and now runs great. This is in regards to the message about the fuel pump continueing to run and only shuts off with ignition.
  • mine did the same thing. I thought my front fuel pump was failing so I was just ran on the back tank
    the problem is in the valve that switches the fuel RETURNING from the injectors.
    fuel pumps constantly from the tank to the injectors. the injectors use only what the injector pulse control computer tells it and the rest goes back to the tank. If the valve fails to switch like mine,running on the back tank will cause the returned unused fuel to returning to the FRONT tank. eventually the front tank will over fill. a new switching valve cured it
  • 6 e250 4.6 has 117k miles and is doing exactly same thing, you ever find a fix? I have changed my fuel pump and no trouble codes tripping :( hellllppppp taken to ford dealer and also private shop and both are trying to get me to parts change with no gaurantee. Ford dealer said fuel pump so i paid them $125 for to tell me that and they where wrong after i installed new pump....
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