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efi 101

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by k5redneck, Dec 21, 2004.

  1. k5redneck

    k5redneck 1/2 ton status

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    well there is good news in my world, i just picked up a complete tbi motor with computer and every thing for 550 bucks out of an 89 blazer. now my problem is that i have never done a efi swap before. and im unshure what im geting my self into. what problems do u think i will have? its geting swaped into a 74 k5 with a 350 auto. i need to have it done in a week because its my dd, so post up any problem that u ran into.
     
  2. Hossbaby50

    Hossbaby50 3/4 ton status

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    Your problem areas will be fuel delivery. You will need an electric fuel pump to supply the TBI setup and you will need a fuel return line to the gas tank.

    If you have the money buy a painless wiring kit for the truck. It will make life alot easier.

    Are you going to swap the whole motor or just swap the injection?

    I would recommend swapping the whole motor if it ran fine when pulled.

    Harley
     
  3. k5redneck

    k5redneck 1/2 ton status

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    im swaping the whole motor in. the motor i have right now has a dead hole and burns oil like gas. i dont have the cash for the painless wireing kit but the stock wireing is still in good shape and uncut. the new motor i got has just been rebuilt about 15k ago and runs strong. i drove the blazer before the motor was pulled. should i get a tbi fuel tank and pump, or use an aftermarket pump and run a return line? if im right i should have a return line allready ran to my fuel pump on the block. can i still use that line?
     
  4. Hossbaby50

    Hossbaby50 3/4 ton status

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    The best way is to get the fuel tank, fuel sender, and fuel pump from an 87+ K5. That will take care of your fuel pump, have the provision for the return line, and take care of the baffle problem.

    Intank fuel pumps are more reliable then external pumps so that makes them better. You can also get spare pumps easier that way since it is a direct part.

    If you don't use the tank from an 87+ the tank will not have baffles in it to help keep the fuel near the pickup when you are offcamber, climbing, or decending. You don't have to have the 87+ stuff, but if you are going wheeling you must keep at least 1/4 tank of gas at ALL times otherwise you can starve the motor for gas on angles.

    You only need 2 lines running to and from the gas tank. 1 sending and 1 return. You can delete the vapor line if you have one.

    When you do the fuel system you will want to run the sending line threw as much Hard (metal) line as possible, and any other areas that need to be softlines should use the MPFI rated line. Normal fuel line is at its upper limit with TBI fuel pressures so be safe and run MPFI line where you have to run softline.

    The return line should also be run threw as much hard line as possible but you don't have to use MPFI softline, you can use standard soft fuel hose. It is only about 5 psi on the return side.

    *********************************************************

    Another problem you will have is no VSS. You will need to splice together 2 of the wires in your wiring harness to make the motor think that your truck is in Park all the time. It is not a terrible thing. My truck has thought it was in Park for 10 months. Its no biggy, but you must do this otherwise the motor won't run right at all.

    *********************************************************

    Another problem will be the 02 sensor. you must get and 02 sensor bung welded into your exhaust (either side and you only need 1) close to the exhaust manifold. Most exhaust shops can do this with ease for you for not alot of money.

    *********************************************************

    Word of advice. Get spare parts and carry them. Also get a troubleshooting manual and carry it also. The spare parts you will want to carry in your truck for the trail are as follows:

    Fuel Pump Relay
    MAP sensor
    Ignition Module
    Pickup Coil
    Ignition Coil
    ECM
    Dielectric Grease
    maybe more I am forgetting

    Harley
     
  5. dyeager535

    dyeager535 1 ton status Premium Member

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    I can't think of one thing that won't swap into your truck that is in the donor. Take every single piece of equipment that is tied into the wiring harness (to include instrument cluster, fuel sender wires, etc) and take every hard piece tied into the system to include evap, EGR, AIR, etc. Don't cut anything, and be careful removing it. Get in a hurry, you will pay for it later.

    If the system works when pulled, if you put it back together EXACTLY like it came apart, then you know it will run fine, right? That means all wiring and hardware, period.

    If you want to work with it after you get it up and running, THAT'S the time to play around with a daily driver. If you start hacking and trying to cut corners before it runs, guaranteed, it will NOT start when you first try. It may be tempting to try and cut corners, but that just leads to weird problems you can't easily trace and people are less likely to know exactly what the problem is or be less likely to be interested in helping you with.

    Yes, the systems will work with less than what is there. Do you want to try and sort that out in a week, or leave it intact, and give yourself more time to figure out what exactly you want/need, and have a vehicle that runs like the donor?
     
  6. pauly383

    pauly383 Daddy383 Staff Member Moderator

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    Well ( Dave standing here ) , he can't get everything , the donors owner is keeping everything to make a big block truck . At least Dave has another truck to drive :xmas:
     
  7. Hossbaby50

    Hossbaby50 3/4 ton status

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    What can you get?
     
  8. dyeager535

    dyeager535 1 ton status Premium Member

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    Umm, $550 isn't sounding like such a great deal unless you get some other stuff with it.

    If he's not going TBI, then he's not going to be able to use most of the fuel system stuff anyways.

    Figure out what he is going to give you, and let us know. $550 sounds high to me without fuel system, etc.
     
  9. pauly383

    pauly383 Daddy383 Staff Member Moderator

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    From what Dave told last night , he can get the tank and anything else from a Suburban the same vintage also sitting in the yard :xmas:
     
  10. Hossbaby50

    Hossbaby50 3/4 ton status

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    It might work if it is the 31 gallon tank. I don't know if you can make the 40 gallon tanks work. It has to be from an FI truck though, 87+ otherwise it is a waste of time.

    Harley
     
  11. dyeager535

    dyeager535 1 ton status Premium Member

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    Yeah but now the fuel lines aren't going to be right, and since the fittings are special, you can't cheaply or easily splice into them, unless you like running rubber fuel line, which I suspect isn't super cheap either. It may sound like a small issue, but last I calculated, to "convert" EFI stuff over to AN was something like $40 just in adapter fittings.

    If the guy isn't running an injection setup on the truck the TBI came from, there is no reason for him not to give you what was there, especially for that kind of money. A Suburban is similar, but still not the same as a Blazer.
     
  12. k5redneck

    k5redneck 1/2 ton status

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    thanks for the input. the guy is working with me to get everything that i need.
     

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