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Thread: Fuel Tank Sender Unit electrical connection questions

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    Registered User 7T1240's Avatar
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    Default Fuel Tank Sender Unit electrical connection questions

    I'm in the process of dropping my fuel tank, and I've hit a snag.

    1. Is there a trick to removing the electrical leads from the posts on the fuel tank sender unit? So far, I have been able to remove the black lead from the bottom post, but despite all types of manipulation I have not been able to remove the yellow upper lead (even though there is a large degree of play between the post and the connector).

    2. Is this style of boot and connector available new? And if so, where?

    3. There are two wires near the sending unit leads which are attached to nothing (see attached photo). One is green/female, one is black/male. What is their purpose?
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    Still plays with cars kenz240z's Avatar
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    The two wires mentioned in item 3 of your post are for an electric fuel pump. My '73 has an electric pump mounted back by the fuel tank, but I don't think earlier years had the electric pump, even though the wires are included in the harness.
    Kenny P.

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    Registered User seerex's Avatar
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    Look inside the lead you have off it might require a long set of needle nose but i think its a pulldown motion and it will come off.
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    Registered User wal280z's Avatar
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    Quote Originally Posted by 7T1240
    1. Is there a trick to removing the electrical leads from the posts on the fuel tank sender unit? So far, I have been able to remove the black lead from the bottom post, but despite all types of manipulation I have not been able to remove the yellow upper lead (even though there is a large degree of play between the post and the connector).
    Why not remove the sending unit from the tank to get a better look at the connection? Those style connectors IIRC, were ring terminals mounted on a stud w/ a nut.
    2. Is this style of boot and connector available new? And if so, where?
    I haven't found them new, but Nissan did use them throughout this time period. I have found them inside, at the fuse box of the 240's, and in the engine bay (ballast resistor) of the 280's.

    Good luck.
    1977 280Z "Lucy" as of 4/05

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    Registered User 7T1240's Avatar
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    Thank you for the replies.

    Ken - Did all '73's come with the electric fuel pump? And was it a supplement or replacement for the mechanical pump in the engine compartment?

    Jeff - I've tried pulling every which way, and even pinched onto it lightly with a needle nose vise-grip. I've been reluctant to get too much more agressive, as the yellow wire feels brittle near the boot.

    Wayne - The connector is a slip on of some type rather than threads and a nut (but the ring terminal is an interesting thought - see below). I believe I will try to remove the sending unit as you suggested. Maybe the proper angle for removal of the lead will present itself with the sending unit out of the tank.

    I'm wondering about the possibility of removing the heads from the posts on the two sending unit terminals, then cutting some threads and using ring connectors with nuts to affix. Anyone have thoughts or experience with this approach?

    Gary S.
    Last edited by 7T1240; 11-27-2005 at 09:11 AM.

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    Supporting Member EScanlon's Avatar
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    Quote Originally Posted by 7T1240
    ...The connector is a slip on of some type rather than threads and a nut ....
    It is a LOCKING Spade connector.

    Remove by sliding aside, the rubber boot which houses the Female Spade Connector to the Sending Unit Stud Terminal. Be careful with these as they're usually brittle. The Female Spade connector looks normal except for the "tang" at the front that locks it onto the Stud Terminal. The Stud Terminal on the sending unit looks like a broad head nail not fully inserted.

    The front of the F. Spade connector has a small "barb" which when completely slid over the Stud Terminal slides down to lock the connector to the stud's head. Lift the barb gently and slide the connector off at the same time.

    2
    Enrique

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    Still plays with cars kenz240z's Avatar
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    Hi Gary,

    From what I know, the '73 240Z's had two fuel pumps: an electric pump mounted back by the fuel tank, and a mechanical pump mounted on the cylinder head. I think the electric fuel pump was added to help with vapor lock problems on the '73.

    Perhaps someone more familiar with this can add details?
    Kenny P.

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    Fuel level sending unit connections update -Over the years, the boots for my original connectors had become rock hard. While attempting to remove them, one brittle wire weakened at the connector inception point, so I snipped off both connectors. After some searching, I found what you see pictured below to use as replacements.

    On the bottom left in the photo is the original boot and connector. Directly above the original boot is a boot I found as a replacement. It is very similiar in profile, although slightly larger in scale, than the original. The bag to the right of the boots has the part number for the replacement boot - 113971901A, and is described as a "wiring boot, shields positive terminal on generator 71-73 bug" on www.wolfsburgwest.com, a VW bug supplier. $3.35 each.

    In the upper left hand corner is a top and bottom view of the connector I used. It slips onto the fuel sending unit post, and has the "tang" previously mentioned by Enrique. The PowerPath package in the upper right corner shows the part number - 784491, described as "GM56 series female housing". I was told this connection is the OEM style connection for a GM water temp. sender. PowerPath is a line name of parts from Federal Mogul.

    Gary S.
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    the same connector covers were brittle aslo when I pulled the tank . I ended up springing the brass connecters some what out of shape . I was able to do a repair with pliers to the point that it held and made good contact. Just to be sure I used sylicone seal to make them water tight also to insure that they remained in place. Actually the rubber boots were so brittle that they cracked when I had to squeese them to remove wires . my 2
    I'd rather die while I am living than live while I am dieing. CZC 1887 IZCC 12602 Member of NorthWest Z Car Club

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