1. Welcome to Jeeps.net!

    You are currently viewing as a guest! To get full-access, you need to register for a FREE account.

    As a registered member, you’ll be able to:
    • Participate in all Jeep discussion topics
    • Transfer over your build thread from a different forum to this one
    • Communicate privately with other Jeep owners from around the world
    • Post your own photos in our Members Gallery
    • Access all special features of the site

93 ZJ Long Crank

Discussion in 'Cherokee' started by TinyInkognegroT, Oct 22, 2019.

  1. Oct 27, 2019 at 10:51 AM
    #21
    TinyInkognegroT

    TinyInkognegroT [OP] Well-Known Member

    Joined:
    May 26, 2019
    Member:
    #3261
    Messages:
    532
    Gender:
    Male
    Vehicle:
    1993 Grand Cherokee Limited 5.2L AWD
    this is after the engine has been idling for 20 minutes now. I'm going to start spraying and see if it starts acting up
    PHOTO_20191027_124944.jpg
     
  2. Oct 27, 2019 at 1:22 PM
    #22
    Awrench

    Awrench Well-Known Member

    Joined:
    May 12, 2018
    Member:
    #2303
    Messages:
    889
    Gender:
    Male
    Vehicle:
    3 jeeps
    fuel pressure is going down faster than a cheerleader on prom night.

    Either the injectors are leaking- there would be trace fuel in engine oil OR the tank check valve located on the fuel pump.

    Engine Vacuum is just like the gauge colors tell us MARGINAL right on the break.
    A warmed up engine timing is computer controlled. We have done a compression test and no leakage or low readings?

    FUEL drop is place (shinny object) to work on.
     
    aggrex and TinyInkognegroT [OP] like this.
  3. Oct 27, 2019 at 2:44 PM
    #23
    TinyInkognegroT

    TinyInkognegroT [OP] Well-Known Member

    Joined:
    May 26, 2019
    Member:
    #3261
    Messages:
    532
    Gender:
    Male
    Vehicle:
    1993 Grand Cherokee Limited 5.2L AWD
    Where do I start and how do I go about it?
     
  4. Oct 27, 2019 at 2:45 PM
    #24
    TinyInkognegroT

    TinyInkognegroT [OP] Well-Known Member

    Joined:
    May 26, 2019
    Member:
    #3261
    Messages:
    532
    Gender:
    Male
    Vehicle:
    1993 Grand Cherokee Limited 5.2L AWD
    We did a compression test back in August but not a current one
     
  5. Oct 28, 2019 at 5:22 AM
    #25
    Awrench

    Awrench Well-Known Member

    Joined:
    May 12, 2018
    Member:
    #2303
    Messages:
    889
    Gender:
    Male
    Vehicle:
    3 jeeps
    OK now I see 18inHg - that is better.

    The fuel pressure drop is your long crank in AM or after a long sit time.
    As mentioned - injectors leaking we may see a puff of black at restart, evidence of fuel in engine oil, maybe wet black fouled plugs, a knock at restart (hydrolock), a code for inj circuit, a RICH code*, BUT I do not think any of those 'tells' are apparent here.
    Next suspect is Fuel pressure regulator**, remove vacuum line- look is there any fuel in the vac line?
    We can clamp off fuel return and do the test again - hopefully with return clamped the pressure stays up there.

    NOW i WILL TRY TO DETERMINE WHICH IS PRESSURE LiNE AND WHICH ONE IS RETURN line.
    And post back later. Coffee awaits,

    PS "I don't like Mondays , Tell me why"

    *IIRC you had a LEAN code.
    ** we were just F'in around here

    ZJ FPR.jpg
     
    TinyInkognegroT [OP] likes this.
  6. Oct 28, 2019 at 8:29 AM
    #26
    TinyInkognegroT

    TinyInkognegroT [OP] Well-Known Member

    Joined:
    May 26, 2019
    Member:
    #3261
    Messages:
    532
    Gender:
    Male
    Vehicle:
    1993 Grand Cherokee Limited 5.2L AWD
    I read you loud and clear and I was actually suspecting the fuel pressure regulator myself because it leaked. I'll go ahead and check out that vacuum line and clamp down return hose when I get off of work today around 5:30 p.m. Central Time.
     
  7. Oct 29, 2019 at 5:19 AM
    #27
    TinyInkognegroT

    TinyInkognegroT [OP] Well-Known Member

    Joined:
    May 26, 2019
    Member:
    #3261
    Messages:
    532
    Gender:
    Male
    Vehicle:
    1993 Grand Cherokee Limited 5.2L AWD
To Top