long travel Outbacks or making Subarus faster and more reliable offroad

[pontoontodd]

B and I worked on the secondary fuel tank for the Impreza.  I pressure tested it and flushed it out, seems like it doesn't have any leaks even at 30psi.  I got the mounting flaps carved up so it fits and matched up the bumper mount holes. 

We had to do a little more hammering in the spare tire well. 

We came up with a plan on how we want to mount the fuel pumps and run the hoses.  I need to get another pump, some hoses and fittings.  Going to try to get wire connectors for the ABS wires so we can use those for the fuel pumps since they're already running front to back and will never be used for ABS again.

B replaced the cabin air filter and cleaned out the airbox and blower fan, they were all loaded with debris.

He also traced the brake lines under the hood and we came up with a plan on eliminating the ABS module and plumbing the left/right steering brake from the black Outback.

[slammo]

You think those ABS signal wires are heavy enough to run a fuel pump, or are you just using them to trigger a relay?

Good thing you have a cabin air filter.

[pontoontodd]

5 minutes ago, slammo said:

You think those ABS signal wires are heavy enough to run a fuel pump, or are you just using them to trigger a relay?

Good thing you have a cabin air filter.

Good point I'll take a look at the gauge of those wires.  Won't be under much pressure so according to the internet it'll draw 4-5 amps and even 22 gauge wire should be adequate.  Definitely not getting any relays involved.

Thanks again for the cabin air filter tip.  We were discussing how full of junk the evaporator would be without it.  Like the one on the black Outback was.

[slammo]

If you're planning on using a full-pressure fuel pump to deliver to the engine bay, the ABS wiring definitely won't be adequate. Plenty of people say the stock fuel pump wiring isn't adequate lol. But if you're just using a transfer pump to move from aux to main tank, maybe the current draw will be low enough.

[el_freddo]

I’d set it up as an aux Fawcett pump to transfer fuel from the aux tank to the main tank. Far simpler than trying to run a second high pressure pump and work out valves/relays to switch fuel lines to avoid back feeding and sort out the redirection of the returning fuel (unless you run a deadhead setup with zero fuel return). 

This sort of thing is something I want to do with my brumby under the tray behind the cab where there’s a decent cavity. 

[Numbchux]

Personally, I don't think I would trust ABS wires. Small gauge, and twisted pairs. Maybe use all 4 rear ABS sensor wires as positives, and then ground to the body

Using this calculator, default voltage drop and temperature, 14v, 5a, 12ft run, they recommend 14g. Alternatively, 22 g wire has about a 20% voltage drop.

[pontoontodd]

19 hours ago, slammo said:

If you're planning on using a full-pressure fuel pump to deliver to the engine bay, the ABS wiring definitely won't be adequate. Plenty of people say the stock fuel pump wiring isn't adequate lol. But if you're just using a transfer pump to move from aux to main tank, maybe the current draw will be low enough.

 

12 hours ago, el_freddo said:

I’d set it up as an aux Fawcett pump to transfer fuel from the aux tank to the main tank. Far simpler than trying to run a second high pressure pump and work out valves/relays to switch fuel lines to avoid back feeding and sort out the redirection of the returning fuel (unless you run a deadhead setup with zero fuel return). 

This sort of thing is something I want to do with my brumby under the tray behind the cab where there’s a decent cavity. 

 

1 hour ago, Numbchux said:

Personally, I don't think I would trust ABS wires. Small gauge, and twisted pairs. Maybe use all 4 rear ABS sensor wires as positives, and then ground to the body

Using this calculator, default voltage drop and temperature, 14v, 5a, 12ft run, they recommend 14g. Alternatively, 22 g wire has about a 20% voltage drop.

Thanks for all the advice on this.  Good to have someone else looking over my shoulder making sure to at least warn me when I'm doing something I shouldn't.

Yes, we're just using these as transfer pumps.  One for each direction since they all seem to have a check valve built in, the only reversible ones I can find are pretty expensive.

14ga seems overkill for 5A.  I use 16ga for almost everything.  Will take a closer look at the ABS wires for sure, I like the idea of just using them for power and then grounding the other terminal of the pumps.  Will probably see what other wires are running back there we're no longer using too.

 

On the topic of wiring, any suggestions on a relay/fuse good for 80+ amps?  Want to put both the pusher fans on the secondary fan circuit.  Figure I'll switch the big relay I add with the stock wiring/relay.  Those fans pull almost 30A each (over 30A when submerged in water apparently).

Planning on putting both the puller fans on the primary fan circuit, they are small and don't draw as much so I should be good there.  Currently have one of each on each circuit on 30A fuses.

[Numbchux]

The reason for 14g was the distance more than the amperage. I used 12 ft, it's erring on the side of caution, but probably a good idea. If 5A is peak, not continuous, 16g is probably fine. But you'll start seeing voltage drop, which can be hard on motor contacts/brushes. The cleanest and shortest path from the alternator would help that.

 

I looked up the stuff I used on my 4Runner. I'm using these in different Amperage ratings, but they're available in many variations.

Maxi Relay + connector and terminals, here's an 80a version of the relay https://www.waytekwire.com/catalog/relays/mechanical-relays-and-connectors/cit-relay-and-switch-a3k1ccq12vdc1-6-maxi-relay-spdt-80a-12vdc-max-145vdc-

Surface mount manual reset breaker https://www.waytekwire.com/catalog/circuit-breakers/high-amp-circuit-breakers/eaton-s-bussmann-series-184080f-01-1-surface-mount

 

I buy a lot from Waytek, or Mouser. 

[el_freddo]

Transfer pumpS? Why plural? Only need one.

[Numbchux]

8 hours ago, el_freddo said:

Transfer pumpS? Why plural? Only need one.

"One for each direction"

I remember him saying he doesn't want to have to separately fill the aux tank. He'd like to flip a switch while filling the main tank to transfer it up to the aux tank. And then activate the second pump to transfer it in the other direction when needed.

[el_freddo]

Yeah righto. That’s against our Australian Design Rules (ADRs) over here. Can’t pump fuel between tanks when refilling. Not saying it isn’t done, just that if you’re found out or cause a fire somehow you’ll be raked over the coals for it. 

And a Fawcett pump would be bloody slow - about 2L per minute transfer rate. Would be better off plumbing in a fill tube between the main tank and auxiliary tank with a one way valve towards the aux tank. There would need to be a vent line to the filler neck to help with the transfer. 

Or just have a secondary fill pipe off the filler neck to the aux tank so it fills after the main tank is full. 

Many ways to do it without over complicating things. Our Pajero (Shogun/Montero) sports a dual filler neck behind the filler cap so we can choose to fill the main tank or the auxiliary tank. This secondary filler pipe follows the main tank until it needs to head to the aux tank. 

Its pretty awesome the first few times being empty on the fuel gauge, then hitting the aux pump switch and watching (from time to time) the main tank gauge go from empty to full without pulling over  

[pontoontodd]

In case you hadn't noticed we have a lot more options for vehicle modifications than Australia.

These pumps are 255lph.  Assuming this extra tank is 10 gallons that would take about nine minutes.  Could have it going before you even start filling the main tank.  Worst case you fill up the main tank, pull off to the side for ten minutes, then go back to the pump.  Guess I'll find out.

I think this will be the simplest way.  One hose connecting the tops of the tanks for venting.  One hose connecting the bottom of the secondary tank going down through one of the access panels and down to the bottom of the main tank.  Have two fuel pumps side by side teed into that bottom hose one pointing each direction.  One of those pumps could run the engine in a pinch.

Definitely looking forward to the magically increased range.

[el_freddo]

19 hours ago, pontoontodd said:

 

In case you hadn't noticed we have a lot more options for vehicle modifications than Australia

 

Yeah I’m well aware of this. In some ways I’m jealous. And in other ways, seeing what dipsh!ts have made regardless of our modification laws, part of me is glad we’re not a free for all! 

Sounds like you have it licked, should be good once it’s all setup!