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No Fuel From Injectors (TBI)

This is a discussion on No Fuel From Injectors (TBI) within the Technical / Maintenance forums, part of the General Discussion category; today i decided to try and fire up the SS and no fuel was spraing out of the injectors. checked ...

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    Registered User KodiakBlack's Avatar
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    No Fuel From Injectors (TBI)


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    today i decided to try and fire up the SS and no fuel was spraing out of the injectors. checked the fuse everything is ok. the fuel pump is working because we took the fuel line off going into the TBI and it poored fuel out. i wiggled some wires or something (idk what i did) and it sprayed for a little bit and started to fire up. turned it off and now nothing. cant get any fuel out of the injectors. does anyone know?? i checked the injectors resistance and they seem to be alright. ???????? im lost. all help is appreciated!! thanks!
    1994 2Door Blazer - 285/70-17, 2" PA BL, 2" Blocks, Trainhorns, Tints, 55w 6K HIDs
    1990 454SS - build

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    Resident Dick Quyonmob's Avatar
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    Re: No Fuel From Injectors (TBI)

    Show any oil pressure during cranking?

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    Registered User 98crewcab's Avatar
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    Re: No Fuel From Injectors (TBI)

    what year ? do you have spark?, if you poor gas in the throttle body will it run?

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    Registered User KodiakBlack's Avatar
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    Re: No Fuel From Injectors (TBI)

    Quote Originally Posted by Quyonmob
    Show any oil pressure during cranking?
    i havnt done an oil pressure check. what would that matter?
    Quote Originally Posted by 98crewcab
    what year ? do you have spark?, if you poor gas in the throttle body will it run?
    i think so, it started to run when the injectors worked for a second. and it fired off starting fluid
    1994 2Door Blazer - 285/70-17, 2" PA BL, 2" Blocks, Trainhorns, Tints, 55w 6K HIDs
    1990 454SS - build

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    Registered User KodiakBlack's Avatar
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    Re: No Fuel From Injectors (TBI)

    Quote Originally Posted by 98crewcab
    what year ? do you have spark?, if you poor gas in the throttle body will it run?
    its a 1990 454SS TBI, yes i think it is getting spark because it fired a bit
    1994 2Door Blazer - 285/70-17, 2" PA BL, 2" Blocks, Trainhorns, Tints, 55w 6K HIDs
    1990 454SS - build

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    Re: No Fuel From Injectors (TBI)

    Fuel pressure regulator go bad maybe?

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    TEE
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    Re: No Fuel From Injectors (TBI)

    Check the dizzy...mine had a crack in the magnet that wouldn't let the injectors fire.

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    Loves GMT400 haters someotherguy's Avatar
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    Re: No Fuel From Injectors (TBI)

    #1 suspect is the ignition module; you can have one that will still spark but not signal the ECM to fire the injectors.

    The pickup coil can be an issue too, but I'd suspect the module first.

    The one thing that caught my attention though is that you said you wiggled some wires and it worked briefly. Take off your air cleaner and the spacer ring under it. Do you see any chafing of the injector wires where the spacer ring sits? This is a somewhat common area for the injector harness to get damaged and short, and it will definitely keep the injectors from firing.

    Richard

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    Registered User KodiakBlack's Avatar
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    Re: No Fuel From Injectors (TBI)

    Quote Originally Posted by TEE
    Check the dizzy...mine had a crack in the magnet that wouldn't let the injectors fire.
    i had the distributor off earlier to fix a snapped screw, so ill take a look at that. thanks!
    Quote Originally Posted by someotherguy
    #1 suspect is the ignition module; you can have one that will still spark but not signal the ECM to fire the injectors.

    The pickup coil can be an issue too, but I'd suspect the module first.

    The one thing that caught my attention though is that you said you wiggled some wires and it worked briefly. Take off your air cleaner and the spacer ring under it. Do you see any chafing of the injector wires where the spacer ring sits? This is a somewhat common area for the injector harness to get damaged and short, and it will definitely keep the injectors from firing.

    Richard
    ill make sure to take a look at that!
    1994 2Door Blazer - 285/70-17, 2" PA BL, 2" Blocks, Trainhorns, Tints, 55w 6K HIDs
    1990 454SS - build

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    Registered User KodiakBlack's Avatar
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    Re: No Fuel From Injectors (TBI)

    bump for help! ps. i replaced the whole ignition coil, nothing! its not getting any spark at all out of the coil!
    1994 2Door Blazer - 285/70-17, 2" PA BL, 2" Blocks, Trainhorns, Tints, 55w 6K HIDs
    1990 454SS - build

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    Re: No Fuel From Injectors (TBI)

    I'm def going with the ICM on this one. Had the same problem last summer and damn if it didn't happen right as I was getting ready to put the boat in the water. Cake fix, and realitively cheap. Just be careful with the harness and plug that go to the ICM, it's very prone to be weak and break... plastic is fail.
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    Re: No Fuel From Injectors (TBI)

    yea man, i'm pretty sure your ignition module is to blame. the only reason i'm not totally sure is you said you "wiggled wires and it started working briefly", that leads me to believe either the injector wires might have chafed on the spacer ring as mentioned above or maybe a rat got into the wiring on its hiatus and chewed one partially. where did you wiggle the wire? if it was around the injectors, check the connectors to the injectors (to include the injector pins themselves) and then check the wiring. also check your grounds.

    but, about the ignition module, it is under the distributor cap, toward the firewall...has two plugs coming out of it. it controls spark AND injector pulse. pretty sure replacing that will fix your problem...even if the parts store tests it and it tests good...replace it. it's cheap to replace (about $30) and i'm pretty sure it's original on that truck...REPLACE IT.

    2004 GMC Sierra SLE Z71 rcsb, 5.3/4L60E/3.73/G80 time bomb...3" lift, tinted 03+ Silverado tails, plasti-dipped 16" wheels (unknown brand), 285/75/16 Thunderer M/T Extremes, Thrush Welded muffler...

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    Registered User KodiakBlack's Avatar
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    Re: No Fuel From Injectors (TBI)

    Quote Originally Posted by FordeatinZ71
    yea man, i'm pretty sure your ignition module is to blame. the only reason i'm not totally sure is you said you "wiggled wires and it started working briefly", that leads me to believe either the injector wires might have chafed on the spacer ring as mentioned above or maybe a rat got into the wiring on its hiatus and chewed one partially. where did you wiggle the wire? if it was around the injectors, check the connectors to the injectors (to include the injector pins themselves) and then check the wiring. also check your grounds.

    but, about the ignition module, it is under the distributor cap, toward the firewall...has two plugs coming out of it. it controls spark AND injector pulse. pretty sure replacing that will fix your problem...even if the parts store tests it and it tests good...replace it. it's cheap to replace (about $30) and i'm pretty sure it's original on that truck...REPLACE IT.
    yeah thats what im gonna end up doin, i cant get it to fire or do anything anymore by wiggling anything!
    1994 2Door Blazer - 285/70-17, 2" PA BL, 2" Blocks, Trainhorns, Tints, 55w 6K HIDs
    1990 454SS - build

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    hucking fates this server FordeatinZ71's Avatar
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    Re: No Fuel From Injectors (TBI)

    well, honestly, that wiggling thing might have been a coinkydink. those ignition modules can act weird when they're dying. on my '91, the first time it acted up i was on a trail. i had just kicked the truck hard sideways through a mudhole...and it died. i figured it got some water in it. tried starting it and it wouldn't do ANYTHING. just cranked over with no sign of firing. took me about 20 minutes of checking things under the hood and cranking attempts but then it fired up, ran rough...cleared up and ran GREAT. ran perfect for another week.

    fast forward a week...i'm on the same trail...same spot...it does it again! same scenario. still thought it was water...

    fast forward two weeks...i get stuck at the end of the trail...not in water at all...i'm letting the truck idle while i'm hooking stuff up...it shuts off like someone turned the key...first thought was ignition module...i was right...put it in, truck fired right up and never put a wheel wrong since...

    2004 GMC Sierra SLE Z71 rcsb, 5.3/4L60E/3.73/G80 time bomb...3" lift, tinted 03+ Silverado tails, plasti-dipped 16" wheels (unknown brand), 285/75/16 Thunderer M/T Extremes, Thrush Welded muffler...

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    Registered User KodiakBlack's Avatar
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    Re: No Fuel From Injectors (TBI)

    just bought the module, so im gonna go put that in right now!!
    1994 2Door Blazer - 285/70-17, 2" PA BL, 2" Blocks, Trainhorns, Tints, 55w 6K HIDs
    1990 454SS - build

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    Registered User 98crewcab's Avatar
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    Re: No Fuel From Injectors (TBI)

    Did the module work?

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    Registered User Cheyenne'88's Avatar
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    Re: No Fuel From Injectors (TBI)

    I guess maybe he's checking the oil pressure by now.

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    Re: No Fuel From Injectors (TBI)

    Or he's out doing burnouts and playing with his new toy...lol

    2004 GMC Sierra SLE Z71 rcsb, 5.3/4L60E/3.73/G80 time bomb...3" lift, tinted 03+ Silverado tails, plasti-dipped 16" wheels (unknown brand), 285/75/16 Thunderer M/T Extremes, Thrush Welded muffler...

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    Resident Dick Quyonmob's Avatar
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    Re: No Fuel From Injectors (TBI)

    Quote Originally Posted by KodiakBlack
    i havnt done an oil pressure check. what would that matter?
    Quote Originally Posted by Cheyenne'88
    I guess maybe he's checking the oil pressure by now.
    I'm glad someone else is aware of the oil pressure switch.

    Too low an oil pressure = no fuel delivery.

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    Re: No Fuel From Injectors (TBI)

    Old thread but I didnt get the result out of this issue... I had same prob. Cranked and sparked but no fuel out of injectors. It does run for a bit if I put a cap full of fuel down the throttle body. Im still thinking what else to look for but I will change the module and see what happens. Thanks for the tips.

 

 
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