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Fuel pump wiring query

EFI Wiring Fundamentals

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Hoping someone could assist with a few queries regarding fuel pump wiring:

I am replacing a low pressure in tank / high pressure chassis pump setup with a high pressure in tank pump in the rear tank of a 1989 F150. I will need to upgrade the rear tank wiring to handle the voltage drop from the higher amp draw.

a) If the fuel pump relay is grounded to the chassis close to the relay, do I need to only size the wire to account for the distance from the fuel pump relay to the fuel pump and then to the fuel pump ground?

b) Excuse my ignorance but with regards to connectors, if I want to run 10/12 awg wire for the fuel pump power/ground alongside say 16/18 awg wire for the fuel sender / rear tail lights, would I have to use two connectors instead of the factory one, as the Deutch DT connectors I see are only suited to 14-20 awg and the DTP are 10-14 awg?

c) The factory circuit has the low and high pressure pumps spliced into the same chassis ground near the tail lights. If I was increasing the power wire size to account for the in tank high pressure fuel pump, would it be best practice to just run a larger ground wire for the fuel pump seperate from the existing ground wiring and just ground it on the same point as the tail lights.

Appreciate any help




A) Yes if you have a short run from the pump to chassis ground point, you can size the wiring based on that portion of the run being short.

B) Fuel sending unit wiring can likely be much smaller than that, perhaps 22-24 gauge, and yes I'd go with DTM for the little stuff and DT for the heavier wires. That also allows you to service the circuits separately.

C) Yes, that sounds great.

Thanks Mike, appreciate the help

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