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1989 Jeep Wrangler 2.5l Runs good until up to temperature, then sputters and dies

Discussion in 'Wrangler YJ (1986-1995)' started by 525JoeyYJ, Dec 27, 2016.

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  1. Dec 27, 2016 at 6:39 AM
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    525JoeyYJ

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    525JoeyYJ [OP] Well-Known Member

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    Hello everyone, recently my 1989Jeep Wrangler YJ 2.5l started giving me trouble... It will start and run great until up to temperature... Once it gets up to temp... It starts to sputter and surge between 300 and 800 RPM or so... Then if I don't keep tapping the gas every second it will eventually die... Restarts up almost right after and runs good for 30 seconds to a minute. Then the same thing happens.

    I've already put in a different EGR Valve with new gaskets, checked the CPS sensor, replaced the Coolant Temperature sensor, replaced the single injector... (Only the one injector because it's the TBI)... I was thinking maybe checking the O2 Sensor... Other than that, I'm stumped!!! I'm sure it's not the fuel pump because it wouldn't run great when it's cold for 5-10 minutes if that was the case.

    Any help would be greatly appreciated!!!!! Thanks in advance!!!!!
     
    525JoeyYJ, Dec 27, 2016
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  2. Dec 27, 2016 at 2:29 PM
    #2
    chris4x4

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    chris4x4 With sufficient thrust, pigs fly just fine Moderator

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    Welcome! Subscribed to see if anyone has any idea
     
    chris4x4, Dec 27, 2016
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  3. Dec 27, 2016 at 8:17 PM
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    C2T

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    C2T Well-Known Member

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    look for vacuum leaks. also, double check your coil for cracks. both get worse with heat.
     
    C2T, Dec 27, 2016
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  4. Dec 27, 2016 at 9:33 PM
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    525JoeyYJ

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    525JoeyYJ [OP] Well-Known Member

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    I will check that tomorrow, thank you.
     
    525JoeyYJ, Dec 27, 2016
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  5. Dec 28, 2016 at 10:34 AM
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    525JoeyYJ

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    525JoeyYJ [OP] Well-Known Member

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    I checked all vacuum lines, replaced one with a big hole in it, no change... Replaced the coil, no change either. Any other advice would be great!!!!! Thanks!
     
    525JoeyYJ, Dec 28, 2016
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  6. Jan 8, 2017 at 1:26 PM
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    JeepGeeks

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    Check your automatic choke, remove the air filter housing and start the engine and watch to see the choke plate adjust as the engine warms up, it is possible it is opening to soon and that is why you have to tap the accelerator to keep it running. Unfortunately if this is the problem there is no recommend fix except to replace the carburetor/throttle body.
     
    JeepGeeks, Jan 8, 2017
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  7. Jan 8, 2017 at 3:43 PM
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    Yj mike

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    Yj mike New Member

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    Check distributor cap. Had one that acted similar and the cap had a crack in it. Replaced and solve the issue
     
    Yj mike, Jan 8, 2017
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  8. Jan 8, 2017 at 4:22 PM
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    C2T

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    C2T Well-Known Member

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    A bad TPS (Throttle Position Sensor) can cause all of this.
     
    C2T, Jan 8, 2017
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    Justanotherjeeper likes this.
  9. Jan 9, 2017 at 7:48 AM
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    OFFGRID

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    OFFGRID Well-Known Member

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    Sounds like it runs fine, until the choke is off and the idle drops. Are you able to increase your idle at running temp to hold 800rpms. Did you ever check your O2 sensor? I agree with Richard on the TPS. My experience with a bad TPS has been a lot of motor hopping when I press on the gas. I love the days when it was just fuel, air, spark. Now it is sensors, computers (ECMs, PCMs) etc.
     
    OFFGRID, Jan 9, 2017
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  10. Jan 9, 2017 at 1:46 PM
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    525JoeyYJ

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    525JoeyYJ [OP] Well-Known Member

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    Thanks for all of the responses!! I changed out the TPS awhile ago, made no difference. I am not able to hold the idle, once running long enough, no matter what I do with the accelerator it dies, but when I step on the gas, it'll rev up a little, but sputter and big back down either until I let off of the gas, or it will bog until it dies if I hold the Accelerater. There is no choke, it is TBI, not carbureted. Replaced the distributed cap, no change... Checked and replaced the o2 sensor. Still no change!!!
     
    525JoeyYJ, Jan 9, 2017
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  11. Jan 9, 2017 at 5:43 PM
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    C2T

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    C2T Well-Known Member

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    Well damn! I am running out of ideas. :annoyed:
     
    C2T, Jan 9, 2017
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    chris4x4 likes this.
  12. Jan 9, 2017 at 6:55 PM
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    OFFGRID

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    OFFGRID Well-Known Member

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    I thought 89s were carbureted. Thats right the 4cyl got the TBI. Next then it is not sensors, it is probably not air, and you said that you replaced everything in the ignition but the distributor. So my thoughts are that it is either the distributor or fuel related, most likely fuel. Do you have an electric pump or mechanical. Being TBI I assume it is electric. Are you getting enough fuel pressure. Have you measured it. I would think you need to be at least 7-17psi at the TBI. I understand that these pumps start failing after 7-10 years of use. I found this discussion between 2 mechanics one trying to fix his 89 2.5 YJ. It is a long read but well worth it for you I think.

    http://forums.4wdmechanix.com/topic/225-jeep-yj-wrangler-25l-tbi-troubleshooting/
     
    OFFGRID, Jan 9, 2017
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  13. Jan 10, 2017 at 8:21 AM
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    525JoeyYJ

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    525JoeyYJ [OP] Well-Known Member

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    My next guess was the pump, but I have no way to test it, I have a tester... But no port to test it!! As it has no fuel rail being TBI.
     
    525JoeyYJ, Jan 10, 2017
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  14. Jan 10, 2017 at 8:23 AM
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    525JoeyYJ

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    525JoeyYJ [OP] Well-Known Member

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    And I'm running out of ideas too!!:frusty:
     
    525JoeyYJ, Jan 10, 2017
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  15. Jan 10, 2017 at 10:25 AM
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    OFFGRID

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    OFFGRID Well-Known Member

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    [​IMG]You need something like this to test your fuel psi. An in line fuel pressure tester/gauge.
     
    OFFGRID, Jan 10, 2017
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    C2T likes this.
  16. Jan 10, 2017 at 12:54 PM
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    525JoeyYJ

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    525JoeyYJ [OP] Well-Known Member

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    Oh okay, so I just cut the line then? And put an adapter or another filter after I'm done?
     
    525JoeyYJ, Jan 10, 2017
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  17. Jan 10, 2017 at 1:08 PM
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    OFFGRID

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    OFFGRID Well-Known Member

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    I wouldn't cut the line. This is just temporary to see what your pressure is. Get an extra piece of line maybe 10 inches long and:

    1. Pull fuel line off tbi.
    2. Connect 10 in. line onto tbi
    3. Connect gauge onto 10in. line
    4. Connect fuel line to gauge
    5. Start Jeep and assess the psi
     
    OFFGRID, Jan 10, 2017
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  18. Jan 10, 2017 at 1:24 PM
    #18
    525JoeyYJ

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    525JoeyYJ [OP] Well-Known Member

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    Oh okay, I see, where can I get one of those testers? And also, if the pressure turns out okay, any other ideas to add to the list? I was kind of thinking possibly backpressure from a clogged exhaust somewhere, but unlikely because it doesn't have a catalytic converter.
     
    525JoeyYJ, Jan 10, 2017
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  19. Jan 10, 2017 at 6:51 PM
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    OFFGRID

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    OFFGRID Well-Known Member

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    This site contains affiliate links for which the site may be compensated.
    OFFGRID, Jan 10, 2017
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  20. Jan 10, 2017 at 7:21 PM
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    525JoeyYJ

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    525JoeyYJ [OP] Well-Known Member

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    Okay, thanks. I've got another thread... About my Comanche... If you wouldn't mind, I'd love to hear your thoughts on that!
     
    525JoeyYJ, Jan 10, 2017
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