98 w900 n14 cutting out while driving

Discussion in 'Kenworth Forum' started by irishluck09, Jul 29, 2022.

  1. irishluck09

    irishluck09 Light Load Member

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    98 w900 n14.

    So wether i'm bobtailing, loaded or unloaded my truck is majorly cutting out while driving. Also like it's not getting fuel.

    It's got a good, new fuel filter, good fuel, the cam/crank sensor is good. At this piont I'm at a loss. My mechanic thinks it could be the wire harness. Computer isn't showing any codes or anything wrong but the cutting out has goten worse.

    Any thoughts?
     
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  3. lester

    lester Road Train Member

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    Check all your battery cables first. At the battery and at the starter. Put a wrench on all of them and make sure clean and tight.
    Second I would check fuel pressure
     
  4. Big Road Skateboard

    Big Road Skateboard Road Train Member

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    Runs fine idling? My first assumption woukd be TPS. I'd watch TPS % and counts on the laptop while slowly pressing and releasing it. You can also use and ohmmeter.

    Then i woukd check fuel pressure, and don't overlook fuel return.

    Any smoke?
     
  5. xsetra

    xsetra Road Train Member

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    My first thought is electric problem caused by moving/ driving.
    Check the wires. Positive and grounds. Sounds like a loose connection or a short.
    Check the fuel pump, power and solenoid.

    2nd thought is fuel system. As driving you need more fuel and you have a restriction or air in system.
    What type of filter, spin on or davco? Air getting into fuel lines.
    Good luck
     
  6. irishluck09

    irishluck09 Light Load Member

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    So the truck idles fine, its just when I start driving. Batteries are brand new, tight and clean. No smoke except for typical small amounts of black smoke when under load. uses a spin on filter and is brand new.
     
  7. SmallPackage

    SmallPackage Road Train Member

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    Does that model N14 still have the old style fuel shutdown solenoid?
    When they get old or are going bad the 12v pt fuel shutdown solenoids are known to overheat and become intermittent while running. They can do this without any rhyme or reason. Start up fine and idle fine but as the fuel warms up coming through them they get hotter than normal and start to cut out causing them to shut off flow if only for a few split seconds at a time. It can eventually just burn out and cause a crank but no start situation.
    Turn the thumb screw in to override the solenoid and see if it fixes the problem. Just keep in mind that the key will no longer shut the engine down.
     
    mile marker 27 Thanks this.
  8. irishluck09

    irishluck09 Light Load Member

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    So im not sure if it has the old style fuel shutoff. Ive only had this truck for about 5 months now. Where is the location of that and I can check to see if there is one on this truck?
     
  9. irishluck09

    irishluck09 Light Load Member

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    Is that solenoid right next to the ECM? Has that small little screen filter next to it?
     
  10. wore out

    wore out Numbered Classic

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    Does the fuel still run through the ECM plate? That plate is before the filter and will catch debris and stop up over time. In one of the elbows between the tank and pump will be a compucheck fitting. Put a restriction on it see if it’s above 5 or so
     
    mile marker 27 and xsetra Thank this.
  11. SmallPackage

    SmallPackage Road Train Member

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    Yes. On the earlier N14’s it was on injection pump. Later it was on the bottom of the ecm.
     
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