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problem with TBI shooting gas in the air

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by solowookie, Sep 15, 2001.

  1. solowookie

    solowookie 1/2 ton status

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    ok guys...

    got everything together, and when I go to start this thing it sounds normal, and after a couple of seconds it will spew gas so hard it shoots it in the air...

    now, the TBI that is in this thing is a 454 TBI... if I throttle this at all then it will start the thing on fire... (the TBI spews into the air)

    it almost seems like no gas is coming, and it will build up and the the injectors will push real hard shooting it so hard it will bounce back up and out...

    any suggestions here???

    <font color=blue> Jeff - may the force be with you</font color=blue>
    <a target="_blank" href=http://coloradok5.com/gallery/Jeffs-Stuff>link to k5's</a>
     
  2. Twiz

    Twiz 1/2 ton status

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    Ya got me on this one.

    - Is it comeing from the fitting on the back of the TBI? They have a O-ring on the fitting that may have been pinched or is missing.
    - If it's leaking from around the injectors. I don't know about those, I've never pulled a injector out of a TBI before, but I know you can.
    - If it's shooting fom the injectors too hard and hitting closed throttle blades, then you totaly got me. I've never seen anything like that before.

    We will stand strong!
    <font color=blue>AMERICA!</font color=blue>
     
  3. solowookie

    solowookie 1/2 ton status

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    [​IMG]

    man Twiz... I'm hoping somebody has an idea on this... man I've put all this work into this stupid thing, and I go to start the thing up and I get this crap. man I just wanna see the thing run!!!

    man I'm exicted to see this thing go... turbo city recommended this 454 TBI, and it has been nothing but troubles...

    <font color=blue> Jeff - may the force be with you</font color=blue>
    <a target="_blank" href=http://coloradok5.com/gallery/Jeffs-Stuff>link to k5's</a>
     
  4. Twiz

    Twiz 1/2 ton status

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    So, have you traced it, is it shooing back-wards from the injectors?

    We will stand strong!
    <font color=blue>AMERICA!</font color=blue>
     
  5. solowookie

    solowookie 1/2 ton status

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    what do you mean traced it???

    I've traced the fuel lines several times, and verified that everything was connected correctly... I traced the fuel lines, and verified they were hooked up like Insane Ewok.

    I'm not sure exactly what to do from here. the TBI's are almost identical. (except for bore &amp; injector size obviously)

    <font color=blue> Jeff - may the force be with you</font color=blue>
    <a target="_blank" href=http://coloradok5.com/gallery/Jeffs-Stuff>link to k5's</a>
     
  6. Twiz

    Twiz 1/2 ton status

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    What I ment was, where is the fuel shooting up from? The TBI, yeah, but where on the TBI? -from the back, from the sides, right from the injectors.

    Basicly, what I'm looking for is more of a description here. If it's shooting out from somewhere, it should be easy to find out where. Just be carefull.

    Just reading this, and not being able to see it first hand, it's really tuff to picture what is going on.



    We will stand strong!
    <font color=blue>AMERICA!</font color=blue>
     
  7. solowookie

    solowookie 1/2 ton status

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    well I haven't been real anxious to stick my head over it so I can watch really well where it is coming from [​IMG]... I'll have to have my wife turn it over in the morning when it is light so I can see exactly where it is coming from... (like I said this isn't something that I've been real excited to do because this thing has caught on fire more then once today when I was trying to start it)

    <font color=blue> Jeff - may the force be with you</font color=blue>
    <a target="_blank" href=http://coloradok5.com/gallery/Jeffs-Stuff>link to k5's</a>
     
  8. Neil

    Neil 1/2 ton status

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    now who was it that posted the other day and said "Have a fire extinguisher ready?" Kinda ironic huh? I know this is not a funny situation. Make sure you wear some eye protection or a face shield of some kind and don't let the engine warm up too much. Find it, shut it off, and fix it is what you need to do. Using a 454 throttle body huh. what kind of fuel pump and pressure regulator do you have? You really need to just see where the spray is coming from for now.....Is this a new 454 unit or a donor? Do you have the 454 computer too? If it is bouncing off of the throttle body blades underneath, maybe the Throttle postion sensor is bad. Be careful whatever you do. Anyways, see where it is coming from............

    Neil H. Alabama.. "It's a full size thang, Jeep owners don't understand!!" '78 K5 400ci 4x4 AT,AC,PW Cheyenne., '74 C10 4x2
     
  9. solowookie

    solowookie 1/2 ton status

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    well I haven't even gotten the engine started yet so I don't think there is much worry about doing it when it is cold(<font color=red>***and just for the record I had an exstiguisher handy***</font color=red>... used it once, the biggest fire about a 2 feet in the air and steady - sure it would have burned out from loosing fuel -, then the other times I was aware so I just used the air compressor to blow it out)

    anyway this is a new / rebuilt from Turbo City... I do not know if this is a reconditioned unit, or a new unit. the fuel pump etc. are all stock on this k5. (I'm not sure where to find the regulator, or how to trouble shoot it)

    I'll find out for sure where it is coming from...

    <font color=blue> Jeff - may the force be with you</font color=blue>
    <a target="_blank" href=http://coloradok5.com/gallery/Jeffs-Stuff>link to k5's</a>
     
  10. K5RON

    K5RON 1/2 ton status

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    The regulator, I believe sits right between the injectors. Also isn't pump pressure controlled by the ECM.

    I'm just guessing, fuel injection is not my expertice.

    Ron
     
  11. Neil

    Neil 1/2 ton status

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    On the units I have worked with (mostly LT1 and LS1) the pump fuel Volume is controlled by ECM and pressure by a fuel pressure regulator/&amp; pump. That is why there is usually a small delay between punching the gas and the kick of power. The ECM when idling is in a closed loop mode and relies more on the Fuel pressure regulator,EGR, and throttle position sensor for idle control as far as ECM readings go.Didn't you say you bypassed the EGR? or capped it? I can't really say any more until you see where the fuel is coming from.

    Neil H. Alabama.. "It's a full size thang, Jeep owners don't understand!!" '78 K5 400ci 4x4 AT,AC,PW Cheyenne., '74 C10 4x2<P ID="edit"><FONT class="small">Edited by Neil on 09/15/01 09:57 PM.</FONT></P>
     
  12. Neil

    Neil 1/2 ton status

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    more important questions. does it do this fuel spraying steadily or in shots spraying upward? Did you unhook the battery and let the computer reset? just based on what you've described it could be a couple of things. ECM fuel management problem, pressure regulator, incorrect timing (some intake valves may be closing at wrong time causing blow back), throttle position sensor......see any leaks though? maybe that will be only a leak.

    Neil H. Alabama.. "It's a full size thang, Jeep owners don't understand!!" '78 K5 400ci 4x4 AT,AC,PW Cheyenne., '74 C10 4x2
     
  13. solowookie

    solowookie 1/2 ton status

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    ok...

    I looked at this, and it is shooting down so hard it is bouncing straight back up... this also sprays in shots at least 3 seconds apart, and comes outta both sides when it happens.

    now I got a custom burn chip from fastchip.com specifically for this app. the EGR is hooked up, but I don't have any smog pumps / air injection etc...

    so the fuel regulator is directly on the TBI... I was wondering if there would be a difference between the 350 regulator and the 454, but if this is on the TBI then the regulator has got to be for the TBI...

    <font color=blue> Jeff - may the force be with you</font color=blue>
    <a target="_blank" href=http://coloradok5.com/gallery/Jeffs-Stuff>link to k5's</a>
     
  14. solowookie

    solowookie 1/2 ton status

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    and p.s. I do not see any leaks in the fuel system...

    <font color=blue> Jeff - may the force be with you</font color=blue>
    <a target="_blank" href=http://coloradok5.com/gallery/Jeffs-Stuff>link to k5's</a>
     
  15. coopertwpk

    coopertwpk 1/2 ton status

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    have you checked your line pressure?you might also take the injectors out of their housing and check the screens they may be clogged ,the spray should be a cone spray not a jet spray.

    88k5 silverado w4"lift <font color=orange>d44 and corp14ff</font color=orange> with 4.11
     
  16. Twiz

    Twiz 1/2 ton status

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    O.K., now that I can work with.
    Possibly; -but not positive-
    - ECM or chip problem: call Fastchip and Turbo city for some kind of daignostic procedure. (yeah, I'm passing the buck, drivabilitys not my thang') Sounds kinda like the ECM is seeing Wide Open Throttle for some resson, but that would be a steady stream of fuel, not pulsed "every three seconds". Which brings up the point, the injectors are pulsed every millisecond, not every second.
    - Sticking injectors, I don't really think that could be the cause. But maybe, somehow..
    - High fuel pressure, The fuel pressure should be between 9 and 14 psi at idle. The fuel pump should deliver much higher pressure (like 30 psi) and the regulator will cut this down to the above specs and return the remaining fuel back to the tank. So, if the regulator is bad, or there is a restricked fuel return line, the the pressure at the injectors would be much higher than the 9-14 psi spec. (maybe high enuff to bounce it off the blades)

    So, I'd check fuel pressure with a gage. and go from there.
    Also, cycling the ign key will "prime" the fuel sys, so the engine does not need to running, inorder to test fuel pressure. And it's not a bad idea to have a gage handy, so any-further fuel delivery problems can be sorted out (fuel pumps) Maybe even "hard" wiering a fuel pressure gaage into the cluster or something.

    We will stand strong!
    <font color=blue>AMERICA!</font color=blue>
     
  17. Twiz

    Twiz 1/2 ton status

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    I have never seen fuel bounce off the blades before, that sounds fishy to me. Sure the timeings on? Cam timeing too. I'd probably check that out too,

    Deffinetly an odd problem you have there...

    We will stand strong!
    <font color=blue>AMERICA!</font color=blue>
     
  18. 502Burban

    502Burban 1/2 ton status

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    Jeff,

    I don't have a lot of experience with the TBI systems, but have spent some time with fuel injection, though. However, it seems to me that Twiztid is on the right track with the fuel pressure issue.

    Just a shot in the dark, but I've had problems before with injectors hosing down the intake when there is a bad ground at one of the sensors. What happens is that the bad ground will cause the ECM to read an rpm signal and believe that the engine is running, even though it isn't. This causes the injectors to fire as if the engine is showing a demand for fuel.

    If the fuel pressure checks out, double-check all of your ground wires, especially the ones for your ECM and distributor. As I said, this happened to me and once everything was grounded properly, the problem went away. When it wasn't grounded properly, just turning the ignition key to the "Run" position would start the injectors firing like crazy and would hose down the whole intake system. When it cranked it would backfire through the throttle body and catch fire.

    Hang in there, and be careful. I know a guy who is semi-bald now due to a backfire through a carb. [​IMG]

    Robb
    '73 GMC Suburban - 502DFI
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  19. CaptCrunch

    CaptCrunch 1/2 ton status

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    Thank you.. thank you [​IMG] [​IMG] ... I'm the one who said had the fire extinguisher ready LOL. Makes sense, but anyways...

    Jeff... sounds like you have either a injector pulse, injector, or regulator problem. You can hookup a test light or buy a noid type test light for the injector plug in to see the pulse. I agree w/ Twiz ... call up Turbo city and see what they think. Ask if the regulator on their's is adjustable? From there call fast chips. This is why we all want good venders to buy from... once w/ customer service and support bother before and after the sale.

    -Mikey
    1987 Chevy K5 Blazer- 350 TBI
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  20. Wheeljack

    Wheeljack Registered Member

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    My first guess is that it is a problem with the chip because the ecm tells the injectors when and how long to open but the injectors should spray fuel seemingly constantly. Also the fuel pressure regulator may be bad or there is a restiction in the fuel return line. because the fuel pump runs constantly and should provide about 15psi of pressure @ all times.
     

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