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93 ZJ Long Crank

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

  1. Oct 22, 2019 at 1:57 PM
    #1
    TinyInkognegroT

    TinyInkognegroT [OP] Well-Known Member

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    Here recently over the last couple of weeks my cranking is getting a lot longer before startup. So far I've ran a fuel pressure test and I get 31 PSI with the vacuum line on the fuel pressure regulator connected and 36 with it disconnected. So much fuel pressure is fine meaning feel is not the problem and that maybe my spark is the problem. I just changed the spark plugs a couple of nights ago so it can't be the plugs, and I've replaced the spark plug wires within the last few months so it can't be the plug wires.... The only option is that are left, distributor and the ignition coil or maybe my wiring isn't right. I'll recheck my wiring but in the meantime can somebody tell me how to test the distributor and the ignition coil?
     
  2. Oct 22, 2019 at 3:39 PM
    #2
    Jim Beam

    Jim Beam Well-Known Member

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    Fuel Injection, Dana 44s, T18, 4.10s w/lockers
    There is a cam and crank position sensors in the also and both have to be working right.
     
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  3. Oct 22, 2019 at 3:45 PM
    #3
    TinyInkognegroT

    TinyInkognegroT [OP] Well-Known Member

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    How can I test all of those?
     
  4. Oct 23, 2019 at 4:39 AM
    #4
    Awrench

    Awrench Well-Known Member

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    You are all over the place - axles, driveshafts, drivability, transmission....

    A long crank time, lets try this,
    when you go to start first thing in AM, turn key to RUN for 3seconds then off then try to start - did cranking time decrease? This sequence will 'prime' the fuel pressure compensating for any leak down.

    How did the Vacuum leak check go? A vacuum gauge would help us assess the overall engine - timing, vacuum - valves etc

    Next look at cooling temp, not so much the gauge but what the PCM is seeing. Is there any cooling issues gauge reading ok?

    TRY the priming tip above and advise.
     
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  5. Oct 23, 2019 at 4:48 AM
    #5
    TinyInkognegroT

    TinyInkognegroT [OP] Well-Known Member

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    Yeah I know I'm all over the place with it LOL Im trying to make sure I check everything and learn as much as I can along the way.

    Okay I'll try the prime trick first thing this morning.

    I sprayed carburetor cleaner on the vacuum lines and didn't get a difference in engine performance.

    I have to wait until Friday to buy a vacuum gauge.
     
  6. Oct 23, 2019 at 5:27 AM
    #6
    Awrench

    Awrench Well-Known Member

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    OK as you saw (youtube) that 5.2 and 5.9 are known for intake gasket issues. Also this era they loved vacuum lines, HVAC , EVAP, EGR, Cruise, and Brakes - all a leak suspect. Don't be afraid of testing with spray.
     
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  7. Oct 23, 2019 at 6:12 AM
    #7
    Awrench

    Awrench Well-Known Member

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    I had access so I copied the specs - if we need them

    93 ZJ fuel spec.jpg
     
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  8. Oct 23, 2019 at 7:44 AM
    #8
    TinyInkognegroT

    TinyInkognegroT [OP] Well-Known Member

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    With vaccum line on fuel pressure regulatorPHOTO_20191022_131345.jpg

    Without vacuum line on fuel pressure regulator...
    PHOTO_20191022_131640.jpg
     
  9. Oct 23, 2019 at 12:18 PM
    #9
    Awrench

    Awrench Well-Known Member

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    thats what we want to see

    LEAK DOWN - Did you turn key to run, then check pressure at 5minutes? key on engine off!
     
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  10. Oct 24, 2019 at 4:42 AM
    #10
    TinyInkognegroT

    TinyInkognegroT [OP] Well-Known Member

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    The prime trick didn't work. And I didn't check the leak down, I'll have to wait until I'm off work today to do it.
     
  11. Oct 24, 2019 at 10:48 AM
    #11
    TinyInkognegroT

    TinyInkognegroT [OP] Well-Known Member

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    You guys don't think it would be my distributor or a my distributor rotor do you ? Is there a way that I can test these things? Or how about my ignition coil ? I replaced the original one with one from the salvage yard about 2 months ago
     
  12. Oct 24, 2019 at 11:15 AM
    #12
    Jim Beam

    Jim Beam Well-Known Member

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    Actually, now that you mention it, I had a fellow club member with one of those 4.0s find a crack in his distributor which prevented an ignition. So why not pull the cap check it for cracks along with a rotor inspection just to make sure. Although I cannot figure what would cause that. I would also check to see just what the fuel pressure is supposed to be set at for your records along with the correct way to read it.
     
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  13. Oct 26, 2019 at 9:49 AM
    #13
    TinyInkognegroT

    TinyInkognegroT [OP] Well-Known Member

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    Is this the right type of kid I should use for my vacuum test?Screenshot_20191026-111826.jpg
     
  14. Oct 26, 2019 at 2:08 PM
    #14
    Awrench

    Awrench Well-Known Member

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    its that simple - old school tool not expensive. Did you ask about loaners or rentals at part stores?
     
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  15. Oct 26, 2019 at 2:42 PM
    #15
    TinyInkognegroT

    TinyInkognegroT [OP] Well-Known Member

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    It's only $14.99 at Harbor Freight. I'm going to go ahead and buy it so I just have one... It'll go with my fuel pressure tester lol never know when I'll need it again. Thought about getting a compression kit too
     
  16. Oct 26, 2019 at 2:57 PM
    #16
    aggrex

    aggrex Well-Known Member

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    Tuffy>AEV>TTO>JW>STech>EVOcage>MagnaFlow>SpiderTrax>RockHard>TF>SpringTail>67design>Bolt>GPCA>Curt>
    Make sure to gather 20% off coupons whenever shopping at HF as well as some freebies. Maximize the jeep bucks.

    IMG_20191014_182734.jpg
    IMG_20191014_182550.jpg
     
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  17. Oct 27, 2019 at 9:52 AM
    #17
    TinyInkognegroT

    TinyInkognegroT [OP] Well-Known Member

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    I have the vacuum tester attached to the PCV hose on the passenger side of the plenum. Is this a good spot or should I attach it to another hose directly connected to the manifold or plenum?
    PHOTO_20191027_115703.jpg
    PHOTO_20191027_114542.jpg PHOTO_20191027_114603.jpg
     
    Last edited: Oct 27, 2019
  18. Oct 27, 2019 at 10:20 AM
    #18
    Awrench

    Awrench Well-Known Member

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    looks good.

    Did anyone ever discuss - bright shinny objects - with you? :)

    let it idle, check vacuum components, the spray trick, mating surfaces, heads to manifold, heads to bock, TB to manifold - any vacuum taps - HVAC, EVAP, EGR, injector O rings,

    Post the idle readings ie 20inHg.

    Its Sunday- Church gets a little long this time of year, warm enough to BBQ, The football is so so, the Bourbon is always good. ITS SUNDAY :drunk:
     
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  19. Oct 27, 2019 at 10:46 AM
    #19
    TinyInkognegroT

    TinyInkognegroT [OP] Well-Known Member

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    https://youtu.be/0nAcrKxyyxM
     
  20. Oct 27, 2019 at 10:48 AM
    #20
    TinyInkognegroT

    TinyInkognegroT [OP] Well-Known Member

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