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Tahoe Fuel Injector Replacement

This is a discussion on Tahoe Fuel Injector Replacement within the Technical / Maintenance forums, part of the General Discussion category; Hello! I have a '99 Tahoe, 4X4, 4-door with the 5.7L Vortec. Truck has just about 130K miles on it. ...

  1. #1
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    Tahoe Fuel Injector Replacement


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    Hello!

    I have a '99 Tahoe, 4X4, 4-door with the 5.7L Vortec. Truck has just about 130K miles on it.

    Replacing the entire fuel injection "spider" as I keep getting a cylinder misfire on number three. I've replaced the cap, rotor, wires, cam sensor, plugs and most anything else I can think of to lick this problem. Nothing seems to work and since RockAuto has a great deal on the full injector set, thought I'd go ahead do the whole thing.

    So, before I embark on this, thought I'd reach out to anyone here, see if someone can point out any "gotchas" that may be out there.

    In addition to the injector set themselves, what else will I need (gaskets, sealant, etc.)?

    Are there any tips/tricks to removing the upper intake manifold to get to these things?

    Are there any specialty tools I need to be aware of to perform this?

    Any estimates as to how long this type of work takes?

    Any other advice or guidance?

    Much appreciated, everyone!

  2. #2
    Registered User 78mc-bbc's Avatar
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    Re: Tahoe Fuel Injector Replacement

    You can get a better price on the spider if you look on Amazon, they have the upgrade mpfi spider for $227.35 shipped.
    From what I've read you also want gasket kit Fel-Pro MS98000T $57.12 shipped from Amazon, and a replacement set of bolts Fel-Pro ES72856 $22.35 also from amazon.
    Probably going to want to get a tube of black RTV.

    That's pretty much what I've read you need and you can probably find a write up on here on doing it

  3. #3
    Registered User masintenn's Avatar
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    Re: Tahoe Fuel Injector Replacement

    I would suggest pulling the distributor and checking the gear for wear before replacing the spider. It is a common part to go bad and cause misfires.


    '96 Tahoe...5.7 Vortec...4wd...~205,000...Stock

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    Re: Tahoe Fuel Injector Replacement

    Thanks for the tips! I am planning on replacing the gear while I'm in there. Been sitting on it for awhile, just not sure how to get the engine to BDC.

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    Re: Tahoe Fuel Injector Replacement

    Good Evening-

    First, thanks a bunch for the tips and for the suggestion of going to Amazon, 78mc-bbc! Really do appreciate it!

    Second, I pulled the plenum off this evening to begin the project while I wait on the parts. One aspect I could sure use advice off is pulling three poppet valves out. When I went to squeeze the ears to pull them out, the ears literally crumbled and snapped. I tried wiggling them out gently with a pair of pliers but no joy. Any advice on removing these three valves without causing any additional problems? I also made the following observations on the spider and the area underneath the plenum:

    1. The area around cylinders 5,7,6 & 8 (area closest to the distributor) appears exceptionally oily/greasy and wet. My mechanic has told me the main seal is leaking a bit, but is this related?
    2. The tip of the poppet valve on cylinder 4 seems to have melted or broken away. It came out relatively easy, so I'm not sure if it broke off or what. Any ideas what that may signify?
    3. The fuel pressure regulator that is attached to the end of the fuel meter body appears to have a nipple for a tube to attach to, yet none was. Should there be something attached? I see nothing in my Haynes manual (but there's a lot of seen that wasn't in the Haynes manual).
    4. How thoroughly should I clean this area? Are there methods to effectively cleaning this area (solvents, etc.)?

    If there are any other items anyone can think of that I should address while I have this area open, I'd sure appreciate it. I plan on replacing the distributor gear while I have this open, but I will begin a new thread to that project.

    Thanks in advance! Much appreciated!

  6. #6
    loose nut behind da wheel JeremyB's Avatar
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    Re: Tahoe Fuel Injector Replacement

    Quote Originally Posted by PhoneMan17 View Post
    Good Evening-

    First, thanks a bunch for the tips and for the suggestion of going to Amazon, 78mc-bbc! Really do appreciate it!

    Second, I pulled the plenum off this evening to begin the project while I wait on the parts. One aspect I could sure use advice off is pulling three poppet valves out. When I went to squeeze the ears to pull them out, the ears literally crumbled and snapped. I tried wiggling them out gently with a pair of pliers but no joy. Any advice on removing these three valves without causing any additional problems? I also made the following observations on the spider and the area underneath the plenum:

    1. The area around cylinders 5,7,6 & 8 (area closest to the distributor) appears exceptionally oily/greasy and wet. My mechanic has told me the main seal is leaking a bit, but is this related?
    2. The tip of the poppet valve on cylinder 4 seems to have melted or broken away. It came out relatively easy, so I'm not sure if it broke off or what. Any ideas what that may signify?
    3. The fuel pressure regulator that is attached to the end of the fuel meter body appears to have a nipple for a tube to attach to, yet none was. Should there be something attached? I see nothing in my Haynes manual (but there's a lot of seen that wasn't in the Haynes manual).
    4. How thoroughly should I clean this area? Are there methods to effectively cleaning this area (solvents, etc.)?

    If there are any other items anyone can think of that I should address while I have this area open, I'd sure appreciate it. I plan on replacing the distributor gear while I have this open, but I will begin a new thread to that project.

    Thanks in advance! Much appreciated!
    #1, your FPR may have been leaking causing this area to be wet

    #2, the heat from the engine makes the plastic brittle and some tabs for removing the poppets may be missing, you can use a small screwdriver to help removing the poppets

    #3 the FPR tube needs nothing attached to it, its inside the intake and senses the vacuum there to adjust the fuel pressure, an external FPR would need a hose attached to sense intake vacuum

    #4 seafoam seems to help clean the upper intake area pretty well

    Good luck with your project

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    Re: Tahoe Fuel Injector Replacement

    Well, gaskets came in yesterday and the injector assembly comes in today. I've removed the plenum and cleaned the area really good, but noticed that the bracket for the fuel module assembly is loose. At first I thought it might be as a result of the vibrations, but before I go cranking this sucker down, is it loose by design to allow the fuel module to fit into the plenum easier? Basically, is it supposed to be loose? Any advice appreciated!

  8. #8
    loose nut behind da wheel JeremyB's Avatar
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    Re: Tahoe Fuel Injector Replacement

    I dont remember mine being loose, but I did have to put a washer under the bracket so the assembly was at the correct height when I reinstalled the upper intake manifold. THe first time it was too low and I couldn't get the wiring harness to fully seat

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    Registered User Alty's Avatar
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    Re: Tahoe Fuel Injector Replacement

    The injector pod bracket is supposed to be loose. The bolt that secures it in place has a special washer attached to it so you can not tighten it solid to the manifold. Make sure to clean around area where the injectors lock into place. This will help the new injectors lock tight into place. Be sure to use some motor oil on the injector pod oring which will help the oring from rolling when you reinstall the upper intake manifold.

 

 

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