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.

Suck fuel through a TBI fuel pump?

Discussion in 'The Garage' started by Russell, May 7, 2006.

  1. Russell

    Russell LB7 Tahoe Status Premium Member GMOTM Winner

    Joined:
    Jun 23, 2000
    Posts:
    7,922
    Likes Received:
    333
    Location:
    Fort McMurray, Alberta
    Hey guys!

    I'm slowly converting my 77 to TBI from carb. However, since the truck is my daily driver, I'm trying to install one system at a time on the weekends, and still have it run carbed, right up until I do the intake swap, and start using the TBI.

    I've got access to a 91 Crewcab that had a 454 TBI in it. While the harness that went to the engine went with the engine, the rest of the cab harness is still there. The owner of the 92 simply unhooked the under dash connector, and unplugged everything, so there are no cut wires to worry about. To make up for the the lack of the engine harness, I have the TBI harness from 89.

    Now, since I am converting my 89 to carb, and my 77 to TBI, I need to know if I am able to draw enough fuel through the fuel pump to feed the carbs on either engine (permenantly on the 89, until I am ready to run the whole TBI on the 77)

    Has anyone got any first hand experience with as much?

    Thanks!

    Russ
     
  2. 87GMC

    87GMC 1/2 ton status

    Joined:
    Nov 5, 2001
    Posts:
    653
    Likes Received:
    0
    Location:
    Olathe, KS 66061
    I converted my TBI truck to carb. I still use the factory pump. I bought a Mallory pressure regulator with a return. It works fine. I'll try to find the part number.
     
  3. Cricket

    Cricket 3/4 ton status

    Joined:
    Nov 29, 2004
    Posts:
    8,224
    Likes Received:
    0
    Location:
    Colorado
    I'm in the middle of diagnosing fuel gremlins on my 77 carb to TBI swap.

    You'll need a carter 5001 Gerotor pump or something similar for the TBI set-up. I'm having some current issues with the return line. The 77 saddle tanks have a 1/4" return pipe at the pick-up that is restricting the fuel return. I'll have to modify the return or go with a fuel cell.

    Lots of fun, good luck on your swap.
     
  4. 87GMC

    87GMC 1/2 ton status

    Joined:
    Nov 5, 2001
    Posts:
    653
    Likes Received:
    0
    Location:
    Olathe, KS 66061
  5. Russell

    Russell LB7 Tahoe Status Premium Member GMOTM Winner

    Joined:
    Jun 23, 2000
    Posts:
    7,922
    Likes Received:
    333
    Location:
    Fort McMurray, Alberta
    I've got the sending / fuel pump unit from the 91 saddle tank. Pump is already installed, and I'll have all the piping needed.

    I've already done two other EFI swaps, so I know exactly what I am getting into already, just never tried sucking fuel through the in-tank fuel pump with the stock engine mounted carb pump. I'd rather not have to spend a bunch of money on regulators and stuff, lol
     
  6. 87GMC

    87GMC 1/2 ton status

    Joined:
    Nov 5, 2001
    Posts:
    653
    Likes Received:
    0
    Location:
    Olathe, KS 66061
    I don't think you will be able to pull trough the pump, but could you pull through the return line. I haven't had my tank apart, but on other cars I've worked on the return line also goes to the bottom of the tank. It should work as a temporary supply also.
     
  7. Cricket

    Cricket 3/4 ton status

    Joined:
    Nov 29, 2004
    Posts:
    8,224
    Likes Received:
    0
    Location:
    Colorado
    Is it possible to eliminate the factory pump and extend the line by brazing or a quick tack weld?
     
  8. Russell

    Russell LB7 Tahoe Status Premium Member GMOTM Winner

    Joined:
    Jun 23, 2000
    Posts:
    7,922
    Likes Received:
    333
    Location:
    Fort McMurray, Alberta
    I'd just extend the line once the truck runs out of fuel. Its just a temporary thing to draw through the fuel pump. We'll see how my 77 does in about a week :)
     
  9. dyeager535

    dyeager535 1 ton status Premium Member

    Joined:
    Dec 13, 2000
    Posts:
    26,979
    Likes Received:
    189
    Location:
    Roy WA
    Return doesn't dump to the tank bottom on the TBI senders, at least. No reason it needs to on any of the senders I can think of.
     
  10. 83ZZ502_Jimmy

    83ZZ502_Jimmy 1/2 ton status

    Joined:
    Feb 7, 2001
    Posts:
    3,103
    Likes Received:
    0
    Location:
    Richmond, VA
    Short answer is yes. Yes you can draw through the in-tank pump. I've done it on several occasions. Works fine.

    To do it correctly, is well, another thing entirely.

    John
     

Share This Page