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What do I need? TBI SWAP HELP!!!!!!!!

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Redfrog, Apr 17, 2002.

  1. Redfrog

    Redfrog 1/2 ton status

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    I did a search and could not find some Info so are my questions

    I need to know everything I am going to need off of a 87 tbi
    system to get it to work in my 79' here is What I know
    intake,harness,throttle body,dist set up,and computer

    What sensors will I need?
    do I need the fuel lines, or can I make them up?
    any brackets?
    will the heads that I have now work or will I need a different intake or a different set of heads?* the heads I have now are
    69-80 castings*
    Do I need any of the emissions stuff like egr or can I dump that stuff?

    If There is anything that I don't have down here PLEASE LET ME KNOW...

    Thanks In Advance
     
  2. azblazor

    azblazor 1/2 ton status Premium Member

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    <a target="_blank" href=http://coloradok5.com/forums/showflat.php?Cat=&amp;Board=blazer4x4&amp;Number=316705&amp;fpart=1&amp;PHPSESSID=>http://coloradok5.com/forums/showflat.php?Cat=&amp;Board=blazer4x4&amp;Number=316705&amp;fpart=1&amp;PHPSESSID=</a>
     
  3. Redfrog

    Redfrog 1/2 ton status

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    That was the post I was looking for Thanks /forums/images/icons/smile.gif
     
  4. Mudzer

    Mudzer 1/2 ton status Author

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    Basically, you will need the following components from the Donor Vehicle. Then you will do the normal 40 hours of wire tracing and sorting (it takes a little while!).

    You will need:

    TBI Throttle Body with all sensors and injectors intact (do not cut any wires, disconnect them at the wiring plug ins)

    Intake Manifold

    MAP sensor

    Fuel lines to the flex line - at least

    Vacuum Lines

    Distributor, Coil

    Exhaust Manifold with O2 Sensor

    Wiring Harness - Disconnect from bulkhead on the Firewall - Be sure to get the wiring inside the vehicle going to the VSS Buffer and the ALDL Connector (Orange, White, Brown and Black wires in a cluster going to a plug-in under dash)
    VSS Buffer and VSS - I found mine on an 87-91 Suburban. I was able to just remove the whole speedometer with the VSS intact, the Buffer is attached to the VSS. I also got the wiring harness all the way back to the Fuel Pump.

    Knock Sensor on the side of the block

    ESC and Computer

    There are typically two switches needed too - Oil Pressure switch (not to be confused with a sending unit, thats a separate system) and a temperature switch (not a sending unit either)

    There are a couple of relays - Fuel Pump Relay and Auto Trans stuff (not real sure about this - didn't care, I have a TH400 no electronic stuff needed).

    Lastly, you will need a fuel pump from a TBI system or a Holley (or any brand with correct pressure and GPH) universal pump, plus a fuel pump return line and a fuel filter for a TBI system (high flow). The best bet for a K5 is to install either a complete tank from an 87-91 K5 or just drop in the sending unit/pump system complete with return line.

    I think this sums it up. As far as the sensors go, you can either obtain a manual with information about the resistance on the sensors described above, then test your junkyard unit to see if it works properly, or just grab them for cores and go to your local parts store and buy all new sensors.

    The wiring harness can be simplified somewhat. GM typically packaged the wiring into one unit - meaning, when you get the wiring from the bulkhead, you will also get some things not needed for this application. These are: Altenator wiring, Oil pressure sending unit wiring, Temperature sending unit wiring and possibly the wiring going to the Windshield washer motor and A/C compressor. If you plan to do a "Stand Alone" TBI system which is recommended, you will want to simplify your harness by removing the above circuits. These affect the system in no way! They do not connect to the computer at all. You can keep your alternator, oil pressure sending unit, and temp sending unit wiring from your existing wiring setup - just route your TBI harness differently, it will be better for future troubleshooting. Now, there is one circuit going from the computer which hooks into your A/C compressor wiring - this is needed if you use A/C because when you kick on the compressor, the engine may stall slightly. This could also be used for on-board air applications. Now, earlier I mentioned something about the Auto Tranny junk. I don't run a trans which requires a lock up converter or anything like that, so its not needed. I have heard talk about the Park Neutral switch situation, some have said to ground the wire - I would not recommend it. I need to ask some of the ColoradoK5 TBI Guru's about what I can do with my old 78 system and Park Neutral on a TH400.

    One thing I will stress, this is not an easy swap unless you have someone decipher the wiring or go with a Painless Wiring harness. I wouldn't go with Painless because the GM system is far better. You will literally spend hours with the wiring harness in your lap and a roll of masking tape/magic marker and marking each wire. You will need a wiring diagram from a Mitchell manual or some GM shop manual. Don't trust the simpified schematics in your Haynes Manual, these do not work. Go to your local Library and find the Mitchell manual for the year you bought the TBI kit from.

    I hope this helps.
     
  5. BadDog

    BadDog SOL Staff Member Super Moderator Author

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    You should also consider "How to Tune and Modify Chevrolet Fuel Injection". Helped me allot. Gives lots of info on what the sensors are, how they work, how to test them, what happens when the don't work, etc. Lots of TPI and TBI stuff in there.
     
  6. Redfrog

    Redfrog 1/2 ton status

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    Mudzer:
    That will help alot. Thanks

    Do I really need the VSS What does it do?
    I am assuming that VSS stands for Variable Speed Sensor.

    Baddog:
    Thanks for the heads up I will order that book in the morning
     
  7. Mudzer

    Mudzer 1/2 ton status Author

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    Yes you need the VSS. This sends the computer into Decel Inleanement and helps fuel economy. I have heard of systems running without them, but I would recommend buying a 87-91 K5 or Burban speedometer and install it in your truck - very simple.
     
  8. dyeager535

    dyeager535 1 ton status Premium Member

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    Actually VSS is in the '82-up C/K trucks, so no worries there about that. 700's (and maybe Th350C trucks) are the only ones that will have the buffer, but AFAIK, all of them have the hookup for the "eye" on the back of the speedo, and the piece that the eye "reads".

    I wouldn't be the least bit surprised if you got an '82 up speedo, that you couldn't swap the speedo head unit between the two vintages. I'm reasonably sure that the two gauges will completely interchange, but to keep matching gauge faces, I'd see if thats not possible. 'Course, if your speedo is not an '85MPH unit, the speedo head swap won't work correctly.
     

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