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Fuel Injection

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by 73/75 k5, Jun 13, 2000.

  1. 73/75 k5

    73/75 k5 Registered Member

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    Question for all you fuel injection users out there or anybody with some knowledge or opinion. I plan on doing the upgrade pretty soon and would like your opinion (if any) on what system to use. After market or look for a tbi set up off of a later model chevy. And anybody using the Holley projection stuff, i've heard mixed reviews on it. Thanks for any info.

    sean
     
  2. ken

    ken 1/2 ton status

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    Do yourself a favor and just find a TBI setup from a later model GM. Easy, reliable and great torque/power.

    ken
     
  3. Mudzer

    Mudzer 1/2 ton status Author

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    I would have to agree with Ken. The Holley system is good, I'm sure but the GM TBI system is far superior. Typical scenerio, you are in Moab and have a computer problem, Go to a local junkyard and buy one for $15. You can buy most sensors at local parts stores. You can probably even buy a new throttle body. The good thing about the GM system is If you do have computer failure, you still can drive it home. It may be less than optimal performance, but you will make it home (from what I have heard). The installation is pretty simple and much cheaper than Holley. If you do go this route and purchase the parts at a junkyard get a few things:

    Write down the VIN number from the vehicle for future reference in the service manuals.

    Wiring harness complete with sensors and connectors. Make sure to either unbolt it at the bulkhead or cut it. Get the ALDL connector (diagnostic port), wiring to Fuel pump.

    Sensors: Knock Sensor, TPS, IAC, MAP, VSS, Temp switch, Oil pressure switch, ESC, O2

    Distrbutor, cap and rotor, Module, Coil and electrical connections

    Intake manifold, Throttle Body

    Fuel Lines, Fuel pump, Fuel filter

    Check engine light from dash if possible

    Exhaust Manifold with O2 sensor

    This is a pretty complete list of parts you will need. It sounds overwhelming but it is a great system and needs this to perform well. Be sure to avoid cutting the harness or sensors off. You want a well sealed and properly spliced wiring harness. Having many splices in the wiring harness will wreak havok on troubleshooting. Usually most diagnostics will only tell you about sensors and their functions, not wiring problems. Take your time. I would be glad to help you if you have questions. I will probably do a writeup on this soon. Go to your local Library and check out a Mitchell manual or Factory service manuals for the year of vehicle you pulled the parts from. The years are '87 and newer V8 powered Trucks, K5s, Vans, Caprices, etc. I got lucky and found a wrecked K5 and I bought the fuel tank and lines from it. I had already purchased the rest of my system from an '87 Chevy Van. Get all the parts listed or if you would rather, take the numbers off them then buy new ones. You can save alot by getting the used sensors as long as they are in good working order. My entire system cost $150 then I bought the tank and fuel pump/lines for $100. It took me about a week of looking through a Mitchell manual and sorting my wiring harness. But it is worth it. Good luck.

    http://www.mudzer.coloradok5.com


    [​IMG]
    Mudzer 1978/91 K5
     
  4. 6.2Blazer

    6.2Blazer 1/2 ton status

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    I also agree that using a factory TBI system is a good idea. A friend of mine recently installed the fuel injection from an '87 Chevy van onto the 350 in his Jeep and is very happy with it during trail use. He thinks he lost a little of the higher rpm horsepower as compared to the 4 barrel Holley he had previously, but the difference in driveability and throttle response (not mention that there is no more stalling on hills) makes it well worth it.
    The one thing he did do during the installation, which made it much simpler, was buying an aftermarket wiring harness set up for this type of installation. This harness eliminates all of the extra wires the factory harness has which are not required for the engine operation and makes the wiring much simpler. I'm not sure of the specific brand of harness, but he purchased it from Jeg's.
     
  5. HarryH3

    HarryH3 1 ton status Author

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    Don't cut the wiring harness where it goes through the firewall. GM builds the harnesses so that the only connections are at the sensor and at the computer itself. There are NO connections anywhere in between to cause problems. The sensors operate at very low voltage and any extra resistance in the wire (such as from a corroded splice or connection) would wreak havoc with the readings.

    There are only about 5 wires in the injection harness that need to be spliced into your wiring harness and none of those are for sensors. The rest of the engine harness is wired directly from the engine to the computer.

    If you're really serious about doing the swap, check out the book that these guys sell. It will answer all your questions and help make the swap as easy as possible. http://www.jagsthatrun.com/Pages/Chevrolet_TPI_TBI_V-8.html

    <font color=black>HarryH3 - '75 K5</font color=black>
    http://ThunderTruck.ColoradoK5.com
     
  6. 73/75 k5

    73/75 k5 Registered Member

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    Thanks a bunch for all the great info. I plan on getting the parts and doing the swap in the next couple of months and now I have decided to go with the stock GM tbi. I'll keep ya updated and if I have any problems I know where to go. "CK5"

    later
    sean
     

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