Welcome to the GMTC - Chevy Truck Forum.
Chevy Truck Forum

GM Truck Club is the premier Chevy Truck Forum & GMC Truck Forum online ~ Since 2004.
Registered Users do not see the above ads. Register Today ~ It's Free and gives access to the whole website.

+ Reply to Thread
Results 1 to 4 of 4
  1. #1
    Sr. Mechanic Big6ft6 is a glorious beacon of light
    Join Date
    Jul 2007
    Posts
    189
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)

    Default what are all these fuel lines coming out of my sending unit?

    It appears that I have 4 different "fuel" lines coming out of the sending unit on my 89 burb (TBI). 2 appear to be pressurized hard lines...

    1) hard line w/filter = main supply
    2) soft line to rear end = rear end breather?
    3) other hard line no filter = ????
    4) other soft line = ????

    Obviously one of the pressurized lines is the main supply (it has the fuel filter on it) one of the soft lines is a breather line coming out of the rear end pumkin.

    That leaves one soft line and one hard line unaccounted for. Both run up to the engine compartment along the passenger side frame rail. What are they? One must be the return line, but which one, the hard or soft?

    And if one is the return line, what is the other one?

  2. #2
    Legend tbplus10 has a reputation beyond repute
    Join Date
    Mar 2007
    Location
    -97.0482020 N, 32.6625890 W
    Posts
    3,395
    Mentioned
    1 Post(s)
    Tagged
    1 Thread(s)
    Blog Entries
    9

    Default

    One should be a vapor line running to the evap canister.
    Tim

    2011 Silverado 1500 LT
    2008 HHR LT
    1999 Tacoma SR5 TRD 4X4
    1993 Jeep Wrangler
    1991 Toyota Rock Crawler
    2009 Harley Davidson Nightrain
    2004 Harley Davidson FLHT "Bagger"
    2003 Glastron GXL Bowrider

  3. #3
    Sr. Mechanic Big6ft6 is a glorious beacon of light
    Join Date
    Jul 2007
    Posts
    189
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)

    Default

    Quote Originally Posted by tbplus10 View Post
    One should be a vapor line running to the evap canister.
    thanks TB...that must be it, the remaining soft line is the evap canister return. The remaining hardline must be the main fuel return. Not sure why the main return needs to be hard line with threaded fittings...return line should not be pressurized?

  4. #4
    Legend tbplus10 has a reputation beyond repute
    Join Date
    Mar 2007
    Location
    -97.0482020 N, 32.6625890 W
    Posts
    3,395
    Mentioned
    1 Post(s)
    Tagged
    1 Thread(s)
    Blog Entries
    9

    Default

    On an injected system the return line is still pressurized, not sure how much pressure. There isnt any pressure reducer on the return line tho.
    Tim

    2011 Silverado 1500 LT
    2008 HHR LT
    1999 Tacoma SR5 TRD 4X4
    1993 Jeep Wrangler
    1991 Toyota Rock Crawler
    2009 Harley Davidson Nightrain
    2004 Harley Davidson FLHT "Bagger"
    2003 Glastron GXL Bowrider


 

Similar Threads

  1. Fuel sending unit
    By jayfire in forum General Chevy Tech Q&A
    Replies: 15
    Last Post: 09-22-2009, 10:27 AM
  2. fuel sending unit help-81 K20
    By bart6180 in forum Chevy C/K Truck Forum
    Replies: 7
    Last Post: 05-17-2009, 11:54 AM
  3. Fuel gage is acting up - sending unit?
    By trailblazer58 in forum General Chevy Tech Q&A
    Replies: 4
    Last Post: 10-30-2008, 12:24 PM
  4. '99 Silverado: Sending Unit? Fuel Pump?
    By Jed in forum Powertrain
    Replies: 5
    Last Post: 07-22-2008, 01:29 PM
  5. Fuel Pump test wire/oil sending unit/ignition mod
    By odb138 in forum Performance & Fuel
    Replies: 3
    Last Post: 01-29-2008, 01:16 PM

Tags for this Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts