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Fuel Pump Wiring  Rating:  Rating
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 Posted: 10-29-2014 05:52 am
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Perhaps somebody in the society could help me with a wiring issue I'm facing.
I'm sorting out the wiring on a late '74 model - #19451. The car hasn't run in years and the PO disconnected many of the wires though it's not butchered by any means. Most of the wiring, including the rear and side marker lights are identical to my early '74 (that car follows the wiring diagrams perfectly). This other car, however, has extra wires stubbed off (lavender colored), a ridiculously long pair of wires for the fuel sending unit, and doesn't have the pos/neg wires for the SU fuel pump. Can anybody help?

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 Posted: 10-29-2014 05:54 am
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PS: I'm only working ion the trunk of this car at the moment (#19451).

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 Posted: 10-30-2014 01:55 am
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Art DeKneef
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Could those long wires go to the trunk lid?
I have 19658 and the wires I remember in the trunk are fuel pump, sending unit, side markers, rear lights and trunk. I would have to pull the wiring harness out to double check but that's what I remember and show on a couple of pictures.

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 Posted: 10-30-2014 01:42 pm
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Brett Gibson JH5 20497
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Don't forget that they also put wires in the trunk for the hard top defroster.

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 Posted: 10-31-2014 05:41 am
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answerman
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Art DeKneef wrote: Could those long wires go to the trunk lid?That's my guess.... check and see if they are connected to the rest of the lights.  I'll bet they are for the license plate lights, which are located right near the latch on the trunk lid.  I just put Ms. J in storage for the winter, otherwise I'd go look and see what color they are.

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 Posted: 10-31-2014 05:56 am
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Thanks for all the replies. I just received the latest JHPS issue and there is a reference in one of the features about subtle wiring differences in these cars. Tomorrow I'll have time to investigate further and will follow your leads to figure this thing out. I'll include some photos as well.

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 Posted: 10-31-2014 11:56 pm
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This may be coming together; I've sorted out all of the rear lights and trunk mounted license plate lights, as well as the fuel sending unit wires but there are some questions.

Photo #1 shows the trunk wires for tangerine #18059. This car was picked up completely intact with all wires connected and seems to follow perfectly the wiring diagrams for the basic JH in color and proper length for their intended usage

Photo #2 is of my blue #19451. As can be seen there are multiple unused wires (The lavender/white that go into nothing and a stub of ground wires under those-almost certainly done at the factory). I've found an additional ground that could be used for the fuel pump, as well as an unused connector that runs power to the window defrost-looking at the tangerine one it is clear that the pump/defrost both work off of the same circuit-on with the ignition.

Now to the front to ground the car properly with a battery-it's a another job under the hood as well-and see if this works. I'm wondering if this is one of late models that got a GT wiring harness. I thought that was only the JH5 but perhaps?

Attachment: IMG_0596.jpg (Downloaded 74 times)

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 Posted: 10-31-2014 11:56 pm
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2nd Photo

Attachment: IMG_0600.jpg (Downloaded 72 times)

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 Posted: 11-01-2014 01:07 am
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Art DeKneef
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If memory serves me the GT harness had the fuel pump wires go down the center of the car and then run along the passenger side of the trunk. The fuel pump was located on the passenger side under the floor on the GT I parted out.

I checked my wiring diagrams for the JH and the GT and neither shows any loose white wires for that area. The only way I know to check those wires would be to trace them back and see where they connect further up the harness.

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 Posted: 11-01-2014 07:22 pm
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gmgiltd
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Ther is also a rear window wiper and washer on the GT - if it is a GT loom which could explain the extra connectors.
Gordon

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 Posted: 11-01-2014 07:52 pm
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The GT loom would certainly help explain some of the extra wires as well as the extra long wires to the fuel tank sending unit (I'm assuming these tanks were mounted under the car). There is still the issue, however, of the colors of these wires not corresponding to the wire chart I found online for the GT. After I sort out the ground wires for the car and install a battery I'll see what works and does't work. I'll post the results and thanks to all for your input.

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 Posted: 11-18-2014 10:18 pm
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Well, the fuel pump is now operating. I guessed that the white wire (the one with the junction connected to the rear window defrost) was pos and ran a new wire to pos fuel pump. I then ran a wire from the pump ground to the black wire that disappears into the loom. It's good to get this stuff working but it would be even better if these wire colors actually matched some of the wiring diagrams out there.

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