Dismiss Notice

Welcome To CK5!

Registering is free and easy! Hope to see you on the forums soon.

Score a FREE t-shirt and membership sticker when you sign up for a Premium Membership and choose the recurring plan.

Fuel pump suggestions

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by CK5, Jul 12, 2000.

  1. CK5

    CK5 In my underwear Administrator Premium Member GMOTM Winner Author

    Joined:
    May 19, 1999
    Posts:
    21,625
    Likes Received:
    702
    Location:
    CO
    I will be doing a shackle flip soon and want to replace the in tank fuel pump while I'm there. I have a bored out TBI (50 mm I think) with adjustable fuel pressure regulator, my question is - Is there a certain brand or model that I should be looking at? Should I go for one with more PSI? talk to me.

    Steve
     
  2. Mudzer

    Mudzer 1/2 ton status Author

    Joined:
    Feb 17, 2000
    Posts:
    3,639
    Likes Received:
    0
    Location:
    Missouri
    Check your pressure at the carb with a gauge. I am sure you have sufficient pressure, but you can adjust your regulator to output more fuel. Only go higher pressure on the pump after you have set the regulator to its fullest and cannot gain any more. Then, I believe you would need a high pressure pump. You should wait and get more advice about this, I am new to the TBI scene. I am just saying what I think is right.

    [​IMG]
    Mudzer 1978/91 K5
     
  3. Shawn

    Shawn 1/2 ton status Premium Member Author

    Joined:
    Feb 17, 2000
    Posts:
    1,753
    Likes Received:
    5
    Location:
    5280'
  4. dumbfounded

    dumbfounded 1/2 ton status

    Joined:
    May 20, 2000
    Posts:
    176
    Likes Received:
    0
    Location:
    Castalia, NC
    I don't believe you'd need higher pressures. With fuel injection pumps are regulated below the highest pressure. A regulator will change pressure at the injectors and it doesn't take much. The problem is with the flow lph (liters per hour) if your engine is needing more fuel then a higher flow pump is needed. A higher pressure can give more fuel per injector cyle but the computer will compensate if it is too high by changing the duty cycle (amount of time injector is energized) So by bumping up the pressure it will decrease the duty and you still end up with the same amount of fuel. You can change this with a custom chip or a programmable ECM.

    Love, Peace, and Hair Grease...........
     
  5. Shawn

    Shawn 1/2 ton status Premium Member Author

    Joined:
    Feb 17, 2000
    Posts:
    1,753
    Likes Received:
    5
    Location:
    5280'
    If you remove the tank, you might as well change the pump with a high flow unit. I think Steves pump is the original with over 160000 miles on it and he was thinking about replacing it anyway. If you start performing serious mods to the stock engine, the stock fuel pump can not keep up. This is the case with all modified Syclones/Typhoon trucks. I know my stock 87 K5 in tank pump is not capable of supplying enough fuel for my 454 so I purchased one at the site above. If your fuel pressure at WOT falls off, that is a good indication that your current fuel pump can not provide the required amount of fuel. Either the voltage to your pump is weak, or your pump isn't manly enough. If you plan on driving your vehicle in its stock configuration for the rest of its days, a high flow pump should is not required. Steve has an adjustable regulator so he can bump the pressure down which results in more fuel going through the lines keeping the lines a little cooler and will not affect the injectors. A 255 ltr/hr pump is good up to 500hp.

    Shawn
    87 K5
     
  6. Steve_87K5

    Steve_87K5 1/2 ton status

    Joined:
    May 26, 2000
    Posts:
    521
    Likes Received:
    0
    Location:
    central NC
    Steve, I took the pump out of the tank because I wanted a fuel system that was field servicable. I have used a Mallory 4060FI for 3+ years and I really like it. It is rugged, and rebuildable, right down to the motor brushes and the stainless gear rotors. I run my stock TBI without any other modifications, and I noticed faster starts and stronger accel right away. If you ever take an in-tank apart: The pump rotors themselves are white plastic and have a D shaped hole on center. These slip over the 1/8" (or less) dia motor shaft which has a small flat spot. These holes eventually get rounded out and pump is dead. Not to mention that the pump/resistor/tubing assy is too weak for off road. I worked for a pipe line co. and our pumps fell off inside the tank regularly. Here is a photo of my 4060FI setup.

    SteveB
     
  7. Steve_87K5

    Steve_87K5 1/2 ton status

    Joined:
    May 26, 2000
    Posts:
    521
    Likes Received:
    0
    Location:
    central NC
    here it is on the truck (Mallory 4060FI)

    SteveB
     
  8. CK5

    CK5 In my underwear Administrator Premium Member GMOTM Winner Author

    Joined:
    May 19, 1999
    Posts:
    21,625
    Likes Received:
    702
    Location:
    CO
    Would the inline cut out (due to elec connections) if I had the Blazer submerged in water or mud? At the why to k5 run I was in a mud bog with the mud over my 36" tires.

    Steve
     
  9. Steve_87K5

    Steve_87K5 1/2 ton status

    Joined:
    May 26, 2000
    Posts:
    521
    Likes Received:
    0
    Location:
    central NC
    I have never had this pump under water. Call Mallory at
    Carson City and ask them, I have called them a few times and have reached people who knew the product well.
    702-882-6600 Mallory. Another thing, the pump makes a very
    pleasing whirring noise and when I turn on the ignition I know I am pumping fuel.

    SteveB
     

Share This Page