Cummins 12 valve-bleed fuel system

Discussion in 'Trucks and Trailers' started by Travis Followell, Nov 30, 2005.

  1. Travis Followell

    Travis Followell LawnSite Silver Member
    from KY
    Messages: 2,206

    A friend of mine ran his out of fuel and he don't know how to bleed the air out the lines and I don't really know either because i'm not familiar with those engines. So is their a hand pump and a bleed screw on top of the fuel filter like most diesel engines have or do you bleed they system another way?
  2. Grassmechanic

    Grassmechanic LawnSite Silver Member
    Messages: 2,697

    Depends on the year if it has a manual pump on it. The owners manual will tell exactly how to do it.
  3. Travis Followell

    Travis Followell LawnSite Silver Member
    from KY
    Messages: 2,206

    It's a 96. He says the owners manual just says if you run it out of fuel to take it to a dodge dealer. He claims that no where in that book does it tell you how to bleed the system.
  4. Restrorob

    Restrorob LawnSite Fanatic
    Messages: 11,029

    I don't know if this is the proper way or not but on our Fords and Dodges all I done is crack all the injector lines on the head 1/4 to 1/2 turn and crank the engine over until fuel started to pump out, Then snug them back up and they would start up and run a little rough at first until all air worked it's self out (couple mins.).
    On the Dodge stright 6 there were two I couldn't get a wrench on easily so I left them and it did go ahead and bleed it's self out with only 4 loosened.
  5. Grassmechanic

    Grassmechanic LawnSite Silver Member
    Messages: 2,697

    Ok. he has a manual pump on it. Mines a 97' and this is from the book:

    1)add 5-10 gallons of fuel to tank.

    2)open hood. Locate lift pump primer button (black rubber plunger underneath brake fluid reservoir). Push down on button until resistance is felt 9approx. 30 times).

    3)start engine.

    Now, I had a problem starting mine using that proceedure after changing the fuel filter. I followed the above AND had to crack the fuel lines, like RestroRob said. It started right away.
  6. Eclipse

    Eclipse LawnSite Bronze Member
    Messages: 1,149

    I would crack the fuel lines at the injector, push the primer botton a ton of times, maybe 50-100. It helps to use a wooden dowel or socket extension or something so you can push it easier going though the wheel well. Leave the injection lines cracked and crank the starter a bit (15 seconds) or until fuel is starts coming out of the line (be careful not to stand too close to the cracked fuel lines when doing this). Tighten the fuel lines and there you go.

    Or crack the lines, hold the pedal to the floor, and crack the starter until you see fuel at the lines. Personally I would prime it a little bit because it is easier on the starter.
  7. rtyus

    rtyus LawnSite Member
    Messages: 104

    Mine ran out of fuel at a turn lane on a four lane highway not too long ago(fuel gauge doesn't work). I just put some fuel in from a jug, and cracked two of the injectors open while an officer turned the ignition over. I was back up and running in about five minutes, although extremely embarrased.Mine is a 90' model, so i'm not sure if this helps or not

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