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88 454 TBI wiring question

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by desertrat67, Jun 27, 2003.

  1. desertrat67

    desertrat67 Hawk Driver

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    OK, i went through yesterday and got my wiring almost completely repaired. I have 2 wires left that were cut when i got it and am trying to figure out where they go. This is an 88 V30(crewcab)

    1. The first is the red wire comming off the fuel pump relay plug. It is supposed to go the the fuel pump prime connector. I have never seen it hooked up, and the wiring diagram shows the prime connector as haveing nothing else hooked up to it.

    2. There is a group of wires running along the backside of the engine directly behind the distributer. I think from the computer. There is one orange wire sticking out that has been cut and i see no matching end for it.

    I will try to get pictures tonight and post them for clarification.

    Pictures showing the routing or connection points would help as well.
     
  2. fortcollinsram

    fortcollinsram 1/2 ton status

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    on My 87 K5, I reused my esisting wiring harness when I swapped in a 92 454...The wiring harnesses are the same (with the exception of length on some connectors)

    For the Red wire coming out of the pump relay, that is the fuel pump test terminal. On older TBI truck, it can be either connected to NOTHING and just have a connectore hanging in the engine bay, or it can be connected to the ALDL connector in the cab. On newer trucks, most of them had the red wire going to the ALDL connector in the cab.

    The orange wire *should* be the connector for the oil pressure GAUGE...These motors has 2 oil press. senders...One for the ECM and one for the gauge. Newer engines have a single sender for both the ECM and the gauge...I believe the 88 has 2 senders...So just hook that up to an oil pressure sender on the block and a gauge on the other end...

    That how it was on my 87 harness which is identical to your 88 BBC harness...

    Chris
     
  3. desertrat67

    desertrat67 Hawk Driver

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    Thakns Chris. Now, i know where one oil pressure sending unit is(left front lower section of block), do you by chance know where the other is? I have owned this for 5 years and have yet to see a second sending unit. Will it be shaped like the other one?
     
  4. Grim-Reaper

    Grim-Reaper 3/4 ton status Author

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    [ QUOTE ]
    Thakns Chris. Now, i know where one oil pressure sending unit is(left front lower section of block), do you by chance know where the other is? I have owned this for 5 years and have yet to see a second sending unit. Will it be shaped like the other one?

    [/ QUOTE ]

    On my 88 454 burb both senders are into the same port on a T at the driverside front of the block down low.
     
  5. desertrat67

    desertrat67 Hawk Driver

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    thanks. I will need to have a look at this stuff tomorrow and find out how it is supossed to be routed.
     
  6. dyeager535

    dyeager535 1 ton status Premium Member

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    Ones a sender, ones a switch. Big difference. The sender is the large bell shaped piece with one wire, the switch is typically a smaller piece that is more like the temp sending unit, but with a two wire plug.

    Switch tells the fuel pump the engine is running, and closes at approx. 5PSI to tell the fuel pump to start pumping. Or, if the fuel pump relay fails, to make sure the fuel pump starts pumping when the engine has cranked long enough to get to 5PSI.
     
  7. fortcollinsram

    fortcollinsram 1/2 ton status

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    ON my 1992 454, there was only ONE oil pressure "thingy" it was BOTH the sender and the switch...I swapped it out for an older switch (it is at the front, lower part of the drivers side of the block)...Then I put the autometer sender just above the oil filter boss on the block for my gauge(there is like a 3/8 NPT port
     

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