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Thread: Fuel Pump Question

  1. #1

    Post Fuel Pump Question

    My fuel pump finally died. I bought a new one to keep my truck running but I can't find one with the top vacuum pump. There is a place in California who will rebuild mine for $175 bucks. I think that is a little steep. I also have seen a few people here mention that the rebuild kits aren't very friendly with modern fuel. All the parts guys say the kits have new neoprene diaphrams that are OK.

    How do you rebuild a stock fuel pump with a basic kit? I am a little unsure how to get the main diaphram out after it is disassembled. Do I have to take out the lever?

    I have plenty of time to do it because I have the new basic fuel pump. So any pointers?
    1969 M715 WO/W

  2. #2

    Default

    Get you a new kit from here, or if you are lazy, they can rebuild it for you:

    http://www.then-now.com/services.htm
    -What We Have, We Hold-

  3. #3
    Join Date
    Sep 1998
    Location
    North Central Wisconsin
    Posts
    11,520

    Default

    Heres the manual section about the fuel pump:

    Fuel and Vacuum Pump Assembly. (Fig 4-9)

    1 Vacuum outlet
    2 Vent plug connection
    3 Fuel outlet
    4 Fuel inlet
    5 Vacuum inlet

    (1) Fuel pump. (Fig 4-10)

    1 Screw
    2 Spring (vacuum)
    3 Valve
    4 Nut
    5 Lock washer
    6 Flat washer
    7 Piston plate (upper)
    8 Piston 0-ring
    9 Piston plate (lower)
    10 Screen
    11 Gasket
    12 Main pump body
    13 Diaphragm assembly
    14 Valve seat
    15 Spring
    16 Valve
    17 Gasket
    18 Cover (fuel)
    19 Screw
    20 Filter screen
    21 Pump valve body
    22 Cam lever return spring
    23 Cam lever
    24 Cam lever retainer pin plug
    25 Cam lever retainer pin
    26 Rod
    27 Spacer
    28 Cover (vacuum)

    NOTE: Thoroughly clean outside of pump assembly with mineral spirits paint thinner and dry with compressed air.

    (a) Mark main pump body (12 fit 4-10) and pump valve body (21) with a file or hacksaw for reassembly in the same position.
    (b) Remove cam lever return spring (22), cam lever pin plug (24), cam lever retainer pin (25) and remove the cam lever (23).
    (c) Remove screws (1) securing pump valve body (21) to main pump body (12). Separate pump bodies. Remove diaphragm assembly (13) from main pump body.
    (d) Remove two screws (19) and washers attaching the pump valve body (21) to the cover (18). Separate pump valve body assembly from pump valve cover. Remove gasket (17), valve seat (14), spring (15), valve (16), and filter screen (20) from valve housing.
    (2) Vacuum Pump.
    (a) Mark castings at vacuum cover (28) and main pump body (12) with a file or hacksaw.
    (b) Remove four screws (1) attaching vacuum cover (28) to the main pump body
    (12).
    (c) Separate vacuum cover (28) gasket (11) and spring (2) from main pump body (12).
    (d) Remove vacuum pump piston assembly from pump body.
    (e) Remove nut (4) and washers (5, 6) securing pump piston plates (7, 9), spacer (27) and piston 0-ring (8) to the pump piston rod (26). Discard piston 0-ring (8).
    --------------------------------------------------------------
    4-5. Inspection.
    Fuel Pump. (Fig 4-10)
    (1) Clean and rinse all metal parts in solvent. Blow out all passages with air hose.
    (2) Inspect main pump body (12), fuel cover (18) and vacuum cover (28) for cracks, breakage and distorted flanges. Examine all screw holes for stripped or crossed threads. Replacement of pump assembly is advisable if one of the three main castings is not serviceable.
    (3) Inspect cam lever (23) for wear
    or scores at point of contact with push rod.
    (4) Discard diaphragm (13) and piston O-ring (18).
    (5) Discard valves (3, 16), and assemblies as these parts cannot be visually checked for wear.
    (6) Discard cam lever (23), pistons (7, 9) and diaphragm springs (2, 13), as removed because old springs may be distorted, weak or corroded.
    ----------------------------------------------------------------
    4-7. Reassembly.
    (1) Fuel Pump. (Fig 4-10)
    (a) Install filter screen and valve assembly (14, 15, 16) into pump valve body assembly (20). Install gasket (17) and cover (18) and secure with the two housing cover screws and lock washers (19). Refer to figure 4-10.
    (b) Install diaphragm assembly (13) in main pump body (12).
    (c) Install pump valve body assembly (21) on main pump body with marks alined. Start screws (1) but do not tighten.
    (d) Install cam lever (23), cam lever retaining pin (25) and cam lever pin plug (24).
    (e) Flex diaphragm assembly (13) to the full up position. Hold in place, and secure valve housing retaining screws (1). Install cam lever return spring (22).
    (2) Vacuum pump.
    (a) Assemble vacuum pump piston lever spacer (27), lower piston plate (9), 0-ring (8), upper piston plate (7), upper washer (6), to the pump piston rod (26) and secure with nut (4) and lock washer (5).
    (b) Install vacuum pump piston in the main pump body bore (12).

    NOTE: Coat O-ring (8) with lubricant or vaseline for ease of assembly and to eliminate piston sticking in main pump body bore (12).

    (c) Install vacuum valve piston spring (2), gasket (11) and vacuum cover (28) in the main pump body (12).
    (d) Secure vacuum cover (28) to main pump body with four retaining screws (1).

    NOTE: Tighten retaining screws evenly to avoid vacuum leaks.
    Lord send your Holy Ghost into our hearts and make the desire of our hearts Your Will.

    Pro-choice, that's a LIE, babies don't choose to die!!

  4. #4

    Default

    Wow what a Post. I have bebuilt two of my pumps. Not to bad. follow the above posts and should be fine. Thats whats great about this site a huge amount of stuff.
    John

  5. #5

    Default

    I just started dissassembly and my pump is missing everything for the vacuum side. A bunch of engine oil made it's way into the chamber. Who ever had it before me rebuilt it but left all those parts out. I thought it was the vacuum diaphram was bad, but it didn't exhist. I volume tested the fuel side and barely managed to get 3 ounces after the engine ran for the 15 seconds (8 ounces or above is needed). The fuel diaphram is not punctured, but streched out pretty good.



    I think I will spend the extra cash and send it to the place Elwenil suggested. They said they would replace everything for a reasonable price. I'm not lazy, Just MECO, Vintage PW, Saturn Surplus and Jeep City don't have the vacuum parts. However the diaphram kits they do have are safe for modern fuel. So, I'll be lazy and get it all done right. Thanks for the help everyone.
    1969 M715 WO/W

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