Question on fuel pump wiring

[R0162]

Hi all hopefully an easy one, i have the swirl pot system installed but the mechanic took power for the lifter pump direct from the Bosch 044, is that ok?

[Rob_W]

If the fuse and wiring feeding the 044 is sufficient for the extra load it would be OK I would have thought.

[R0162]

Well it is a big thick wire from starter to relay with 20 amp fuse, and then not so thick from relay to 044, then he has put another ring connector from 044 to the lifter pump...should he have gone from relay?....

p.s the original 044 wiring upgrade was done by NM so i'm not sure if that will give you an idea of what thickness wires have been used...

Edited by R0162 on Saturday 31st March 20:24

[TuxMan]

Chris , safer to run another supply from starter with another relay , if your lifter pump pulls more than 5 amps your 20 amp fuse is not going to be big enough , also if the relay is rated at 30 amp it's going to be working pretty hard to feed both !!!! Tux

[XLRONYX]

You definitely want to run a separate wire for the lifter pump. Wire resistance causes the voltage to drop from the source end of a wire to the destination end. More current means a bigger drop in voltage. Here's a made-up example: Suppose your supply is 12 volts, both pumps draw 10 amps, and the wire to the 044 causes a 1 volt drop at 10 amps. Your circuit will now pull 20 amps through the wire, so instead of seeing 11 volts, your 044 will see only 10 volts. The lifter pump will see even less than 10 volts. With separate wires, both pumps would see 11 volts.

I'd run them from the same fuse, though, to make sure that if one goes out, they both go out.

Jeff

[R0162]

thanks for that info...i will run a separate wire from the relay.....i have been doing a bit of reading and the facet red top only has a average 1.6 amp draw....whereas the 044 can pull 18 amps max?...so i think the relay is ok..but should i upgrade fusen from 20 amp?..in theory it should still be ok...