Fuel Pump Wiring Upgrade

[Rusty]

Hi all, just wondering if there was a how to on this? I'm sure I could work it out pretty quickly; just wanting to get the parts up together.

I guess I'll need a standard relay with spade connectors to suit and some wire to run from the battery to the relay and relay to fuel pump, as well as an earthing lead for the fuel pump feed from the wiring harness. Anything else?

[QuattroFever]

a bucket of patients as always.

[S2central.net]

You could do it nice and neatly with a spare relay block under the rear seat if you wanted to be very fussy, but what you describe is sound enough...

Simply intercept the green/yellow wire going to the pump and use that as the trigger into a relay which gets fed much closer by the battery sitting nearby... you could of course splice back into the green/yellow wire in the loom going to the pump if you get my drift.

Might be an idea to measure pump volts 'before mod' then see what a partially wired in relay is going to provide before you commit to hunting and cutting wires.

Only advice to you is be sure to insulate spade terminals nicely under the rear seat... I know someone who had a short circuit caused by metal frame under the rear seat - bit of a freak accident but hey !

[S2central.net]

The factory cable is fairly skimpy 1.5mm2 - you could reduce voltage drop further by running heavier cable from relay to pump (and its earth strap)

[Rusty]

Nice. I like the idea of using the relay holder under the rear seat.

What sort of current does the pump draw? I was thining of 30A wire as a bit of overkill.

Don't suppose it matters where I earth the original feed... does it? Next to the relay seems sensible but I can earth it at the OE point, if there's a specific requirement to do so.

[S2central.net]

Pump fuse is only 15A so its fair to assume approx 10-12A consumption but I have never measured... Beefing up cable is probably a bit OTT here - given the short distance of the new run.

Tricky bit for tidy job under the seat is finding the right flavour of relay block that caters for the normal 4-pin relay footprint. I'll have a look on that.

[Rusty]

I'll look into wire prices but there's little harm in going OTT if it doesn't cost much extra. Seems to be fairly simple, just the matter of the live not being switched in the fusebox.

[S2central.net]

I would say that 443 937 527 or 528 are the best bets... only niggle with these is some trial and error to get the right pin types for them....

Suppliers like polevolt will have a standard 4-pin relay block with a bracket to screw onto chassis that works with the standard blade inserts - the tagged ones that lock when inserted. That is probably the path of least stress here.

[S2central.net]

Just remembered I bought some of them recently... yes i have a few spare... send me a PM if you want me to post it ya.

[S2central.net]

One of these I mean - http://www.polevolt.co.uk/acatalog/info_RBS1UKIT.html

Cost a whopping £1.20

[Rusty]

Cheers. I'll have a look under the seat and what I can get locally to make it all fit

[terrybullwon]

Any one checked the specs for a standard pump or is this 044?

[Rusty]

Stock; I don't need anything bigger at the moment. Just want to make sure that what I have is running to its best potential, rather than being choked a little

[terrybullwon]

I am pretty sure stock wirring will be just fine

[S2central.net]

I'd agree on that.... a lil wee daisy chain thru a relay under the rear seat might save you half a volt though !