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My trucks fuel psi and injector q's

This is a discussion on My trucks fuel psi and injector q's within the Technical / Maintenance forums, part of the General Discussion category; 88 k1500 350ci Since the temps got cold again about two weeks ago, truck has had a bad hiccup upon ...

  1. #1
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    My trucks fuel psi and injector q's


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    88 k1500 350ci

    Since the temps got cold again about two weeks ago, truck has had a bad hiccup upon acceleration when cold, acts like it's going to die, sometimes backfires thru the tb. Acts like it's out of gas.

    I hooked up the fuel pressure gauge, got about 8 psi in start position, psi drops rapidy tho

    Got 11psi idling, turn key off and psi drops quickly.

    Going to find a rubber return line and clamp it tomorrow and see what happens.

    I've check the lines for any kind of fuel leak, none found.

    Haynes is a little confusing, says that if the psi drops fast, there's either a:
    leak in the main line
    faulty fuel pump modulator check valve
    leaky injector

    q's:
    What's the mod check valve, part of the fuel pump? I just replaced the pump, and had this condition at times before then.

    Will the injector leak back into the fuel lines, rather than the tb? I wonder if I can check them out visually.

    Does this sound like an injector problem?

    I've read up on the fuel pressure and fuel injector threads on this site, and am suspecting its the injectors.

    Can I use an injector cleaner bottle to try and clean them?

    After this started again this last time, I used seafoam in the tb and tank, and some premium fuel, no improvement.

    Has anyone bought the 87-95 350ci injector pod off ebay and tried it out?

    The backfiring and poor performance usually clears up a bit after a few blocks, but there is always a noticable dead spot on the throttle, about 1/4 way, and throttle response is not good.

    Thanks all :)

    BTW, truck has unknown miles, had 116k when I bought it, but the odo didn't work.
    Last edited by MXHaloFan; 01-24-2009 at 08:19 PM.
    89' K2500 SLE 350/700R4 ECLB 270K 4:10 gears Dual Efans
    Rebuilt tranny, all new AC parts. 95 mirrors, 6.5's in the doors.
    Soon: 94' instrument cluster and power window/locks

  2. #2
    JUGS Racing SuperStepside's Avatar
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    Re: My trucks fuel psi and injector q's

    Do the injectors leak with the key on, engine off?
    Last edited by SuperStepside; 01-24-2009 at 08:36 PM.

    1995 350 "Tool Box Injection"
    Going 4/6 with 20" Billet Specialties

  3. #3
    Registered User Bowtie00's Avatar
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    Re: My trucks fuel psi and injector q's

    sounds like fuel pump
    2000 Chevy Silverado 1500 4.3L 5 Speed

  4. #4
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    Re: My trucks fuel psi and injector q's

    update:

    Installed a new fuel filter, and now I can get 11psi with the key,

    clamped the return line, and I can get 25 psi and holding fine

    but the psi will drop fast with no return line clamp

    Does that mean my FPR is leaking into the return? Hate to ask, but my haynes is a little confusing.

    Also, if it's the fpr, which one should I get? Borg Warner at Oreilly's for $48
    89' K2500 SLE 350/700R4 ECLB 270K 4:10 gears Dual Efans
    Rebuilt tranny, all new AC parts. 95 mirrors, 6.5's in the doors.
    Soon: 94' instrument cluster and power window/locks

 

 

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