^^
Good question
I did end up using a very large capacity fuse on a trunk batt relocation on my Subaru.
I didn't run one for a few months (using a Longacre 0ga wire kit http://www.hrpworld.com/index.cfm?tpc=Batt...&action=product )

I just made sure wire was routed where it wouldn't get cut/damaged

Then I thought I would try a fuse, so I got a 150A fuse at Autozone. It was only like $4 and I just wired it in together with a batt cut-off switch.

I tested it many times at full load, cranking the car with high beams, stereo, A/C, and fan on (though most accessories get cut off during crank) So far after more than 6 months, the fuse is holding up. I'll see if I can find the exact part number, or take a picture of it and post it.

Just peace of mind, though I never seen any posts of cars with massive shorts from batt relocation wires.

 

You want the fuse to match the ampacity of the smallest cable of the branch circuit. You can always go smaller for more protection, but never go larger.

 

Mine still whined having it wired this way.

Seems like some Walbros are just noisy. I've had some that were silent, I've had some that were whiney. Regardless of wiring.

 

Touching on the question I asked earlier about the fuse for the battery cable.

I went down to Advanced or Auto Zone, whichever it was, and picked up a 150amp breaker.

It's pretty cool, just like a breaker for your home, has a simple red reset button.

It's also very handy if you park your car for an extended period of time, you can also "trip" or open the circuit and it will help keep your battery from slowly draining.

It cost me $27.00 bucks I do believe.

 

Bumping this thread because of the awesome information!

Question: Is it always recommended to "upgrade" the power cable to the fuel pump?
I'm replacing my walbro with a HRC 255LPH this week and i'm wondering if should also do this mod.

 

It doesn't hurt to do it, but depends on your goals I would say. If you want to start pushing the pump or fuel pressure, I would definitely do it. If you're shooting for mid 300whp, I don't think its necessary.

 

Well it seems like the walbros can get bad with the 12v in stead of 14.x v... So i would do this mod to have better pump reliability..

 

I'm also going to do it at the same time I install an amp (different wires, of course). I have a slight lean spike at 6000-6500 and think this upgrade will help that. My fuel pressure lags behind the boost a split second, so I'm thinking the pump isn't pumping fast enough, although it catches up the demand by 6500

 

I'm a little bit confused about connecting the relay..

there are 2 yellow/black wires going to the pump as well as 2 black wires...

in the picture above it seems like that one yellow/black wire is cut and split to the relay.. which of the 2 wires do i need to split?

 

the way i understood it is this.

stock power wire to fuel pump now activates the relay.
one wire goes from relay to chassis to ground the relay.
one wire goes from battery to relay to power the relay.
one wire goes from relay to fuel pump to power fuel pump when stock power wire turns on relay.


this picture is awesome and worked for me props to the artist!!!!! . i didnt use crazy guage wire either. my battery is in back of car, i ran a 30 amp fuse with i think 12 guage wire, now that i think about it might be 10 to the relay, and then 12 guage wire to the pump stock wiring. remember, the pump was fine on the stock thin shit. we are just making sure the pump gets the full 12-14volts as oopposed to the 10-12 it gets on stock wiring. this will make the pump louder FYI.