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Posted by: Mark Henry May 10 2022, 10:52 AM

The PO on this teen was running carbs, he relocated the pump to the front and ran a single wire from the pump black/red wire to the front and just grounded the pump.

I'm replacing the engine with a 1.7 Djet, do I need to run a 2nd wire up front for the ground? And is running the wires from the rear up to the front the preferred wiring solution?

Thanks

Posted by: Dave_Darling May 10 2022, 02:34 PM

On D-jet, the FI operates the fuel pump relay. It's not a simple "just switched power" thing. So you will want to at least run the power wire up to the new pump location.

I prefer running it along the main wiring harness, which can be ... umm, a challenge in spots, but is the cleanest way IMHO.

The other wire for the fuel pump is just a simple full-time ground. So you can ground the front-located pump anywhere, you don't have to run a specific wire for it.

--DD

Posted by: JeffBowlsby May 10 2022, 02:39 PM

Mark, recall that the power wire needs to be a heavier gage wire than the standard 16 (?) gage wires at the engine bay Fp location, due to its extra length. Go into the 14 pin plug at the relay board.

The 75-76 car schematics depict this heavier gage wire.

Posted by: GeorgeKopf May 10 2022, 06:00 PM

With my wiring harness (1973) out of the car, I moved the fuel pump wire from the engine bay to under the fuel tank. I only have the wiring diagram from a 1974 and it shows a 1.0 on the black/red wire.



I spliced the wire, with the same thickness, to get it to reach. Is the standard practice to replace the entire wire with a 1.5 thick wire?

If the schematics notation for the 1.0 is in millimeters, then:
1.0mm ~ 18 gauge
1.5mm ~ 14 gauge

Edit: I just found a pelican post where a 1975 owner states the wire to the front fuel pump is 14 gauge. I'll have to check mine and see what it is and replace if necessary.

http://forums.pelicanparts.com/porsche-914-914-6-technical-forum/943996-914-fuel-pump-current-draw-question.html


Thanks.

George

Posted by: Van B May 10 2022, 10:06 PM

I ran 14ga to the front. And I ran both wires just because it was easy. The PO for my car grounded it to the body, but I viewed it was another place for a bad ground to develop.


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Posted by: Mark Henry May 11 2022, 03:49 AM

Thanks everyone, the PO did run a heavy 12ga wire to the front and I did find a white wire (18ga) I believe he was using as a ground, but it was just grounded to the body.

The pump is relocated in the trunk and I didn't like how the wire was run, so I pulled the wires out back into the cab (over a year ago). Now the wife doesn't really want the 914 and I just want to get it up and running and ready to sell, so the easiest way is to put it back as it was.

Posted by: Spoke May 11 2022, 05:13 AM

About the ground wire for the fuel pump, running a separate wire for ground from the engine bay to the front trunk is somewhat counter productive. The fuel pump gets its power from the battery and the battery ground is the chassis.

The lowest impedance ground for any component is the chassis. Thus you will have less resistance between the battery and the fuel pump by finding a local chassis ground right by the fuel pump.

If one decides to use the local chassis for ground for the fuel pump, that connection be it a stud or some attachment bolt, must be very clean and paint-free.

Posted by: Olympic 914 May 11 2022, 06:16 AM

Also ran a 12 ga wire from the rear to the front, I periodically placed red heat shrink along its length to somewhat mimic the black/red of the original wire.

12 ga brown for ground to the ground point under the dash on the left. But as others have said any good chassis ground would work, like the point near the headlights.

Posted by: GeorgeKopf May 11 2022, 12:18 PM

Found the correct gauge and color on ebay.

eBay item number:184538340023

Posted by: ClayPerrine May 11 2022, 02:05 PM

I pulled the wire back from the original location in the harness, and ran it forward. I then extended with a same color/tracer/gauge wire, following the harness until it made it under the tank. I added a brown wire that goes back to the ground point by the fuse block.

Clean and looks stock.

Clay

Posted by: windforfun May 11 2022, 04:08 PM

QUOTE(Van B @ May 10 2022, 09:06 PM)

Posted by: Van B May 11 2022, 04:44 PM

QUOTE(windforfun @ May 11 2022, 06:08 PM)

QUOTE(Van B @ May 10 2022, 09:06 PM)

I ran 14ga to the front. And I ran both wires just because it was easy. The PO for my car grounded it to the body, but I viewed it was another place for a bad ground to develop.

One must be well grounded.

Posted by: Nogoodwithusernames Mar 21 2024, 10:41 AM

Sorry to revive an older thread, least it's only a few years old. Anywho, I replaced the old three port pump ages back it seems and put the new inline pump in the same spot behind the passenger seat but would like to finally get around to moving it up to the front of the car. Does anyone have some better details of wire routing? All of my manuals are still packed away from moving last year. Do I need to drill any holes for the wiring or is there room in a stock '74 to squeeze two extra 14ga wires through?