Thread: Plumbing sill tanks

The best way for sill tanks to work on an EFI system is to leave the EFI hoses to and from the engine strictly alone. Run a small pump from each sill tank's pickup connection to a spare fitting somewhere on the rear corner tank. Run a breather from each of the sill tanks to a fitting at or near the full level of the rear corner tank. (You may have to drop the tank to get at/fit suitable fittings. Some people just use the drain plug as an inlet.) That way it won't overfill it if you leave a pump running, just pass back some of the excess fuel to either sill tank.

To manage the freshness of the fuel, leave the sill tanks empty unless you need the range, and just make sure you use/replace any fuel in the whole petrol system within 2-3 months depending on the season. If all the tanks are airtight to the main filler cap there will be less chance of water vapour being sucked in and rusting the tanks or fittings.

BTW there's no such think as "LPG scuba tanks" it's sloppy language and only misleads people. They are simply small LPG tanks.

Thanks Bee Utey, does this mean that the whole system is pressurised.

Re "scuba tanks" makes sense, as a diver, i wouldn't want to confuse them.

Given that I'm starting with nothing, does anyone know where in Melbourne I can source all the plumbing bits - pipes, pumps, filters, etc...

Originally Posted by Ezeman

Thanks Bee Utey, does this mean that the whole system is pressurised.

The whole system is sealed, the pressure is controlled by the functions of the fuel cap and the evaporative emissions stuff, i.e. the charcoal canister and the purge valve. You're trying to not waste fuel by evaporation and risk water entry and rust by condensation. That's apart from the fact its a legal requirement that all auxiliary tanks function in the same manner as the original tank and ventilating system, in the sense of stopping unburnt hydrocarbon emissions.

Thanks Bee Utey. That clears up a nagging question.

Now i just need to get on with the plumbing. Any ongoing assistance would be appreciated.

I'll draw up a diagram and post it for comment.

When it comes to mounting the tanks, there should be brackets on the ends of the tanks. Mine have angle brackets bolted to these and they bolt to the outriggers near the sills. There is another bracket near the chassis that you can bolt to a bracket assembly on your chassis. This spreads the support on the tank unlike straps around the tank and chassis, like trucks have.

I haven't installed mine yet, it's still a month or two away (more important stuff to do first) so I have no pics to help

Hope that helps

Neale

My 85 Rangie was carbed but this is how i mounted the sill tanks.
I used an T/case mount bolt on one and drilled the other hole and fitted a crush tube .

Top tip before fitting the sill tanks is to install a fuel level gauge.
I used the Capacitive type dip stick sender unit and have the left & right guages above the rear view mirror.
The sender units sit flush with the top of the tanks so you don't lose any ground clearance.
I used good quality transfer pumps and put a filter in line as well.

The basic schematic is to plumb the two sill tanks into the main filler tube going into you main tank. Mine didn't come with a decent diagram but it's not hard figuring out what goes where.Be sure the inlet to the main tank sits higher than the top of the tank other wise you'll syphon full every time you fill the main tank!

I originally bought a pair of VDO senders that were the correct resistance for the LR gauge but never fitted them.