Problems with aux fuel tank

Must add too that i am currently doing a house sit near Port Augusta so if anyone knows an expert with mods to aux fuel in SA ??!!

Hi Brian,

While you are enjoying your house sit, please send more information about your vehicle.
This is so we mere plebs cans try to give sound information on you query.
Standard tanks or AM fittings would help.
Yehicle model and year, would be a BIG help.

With that, we will see where we go....................

Cheers,
Wayne & Sally.

G'day Brian

I too had this problem on my Mazda BT 50.
It's a bit hard to explain, but I will try.
In my case a vent line ran from auxiliary tank to main tank,
unfortunately this line was too long and dipped below the main tank.
Auxiliary tank is above main tank.
While driving fuel was spilled into vent line and because of it's position
it stayed there.
This line no longer acted as a vent and consequently it took forever and a day
to fill auxiliary tank.
After much frustration, when filling, I ran a separate hose from the filler into the aux. tank which then became the air vent.
This fixed the problem but I could not work out what was wrong.
Took car to garage in Alice Springs and on inspection fault was corrected.
Vent line was shortened and fuel was no longer able to stay in line.

I hope this makes sense,if not let me know and I'll try to clarify.

why on gods earth would you vent one tank into the other ,
never heard of it before , run the vent pipe from each tank up to the top an just below the cap on the filler neck ,works every time
mechpete .

Brian
The vent from the aux should be "Teed" into the hose which goes to near the highest point on the filler neck.
Around 8mm hose from memory.

That hose allows the main to vent and will also allow the aux to vent unless the neck is totally full of fuel, then it bubbles and blurts back if neck too full.
Next to the neck,

Because the two fillers are next to each other you should be able to direct the nozzle flow into the aux or the main, at will.

Next to the filler neck but forward slightly is a tank vent collector with around 5 hoses connected to it. it is black ribbed plastic, but sorts the vents lines from the main tank so air can escape to that top 8mm line but return fuel to the tank..
Possible any of your aux tank, additional vents, should be plumbed with a t's into a couple of those lines too.
That should make it all breathe correctly with minumal blowback and airlocks.Well no more than usual anyway.

I always used to rock the vehicle when near full to get the air to find it's way to the top 8mm line which vents high in the neck.

PS You have to remove the rhs inner trim to get to the vents system. It will all look like a tin of thick black worms with additional lines connected.

Brain if you have a later model cruiser the problem might be the same as those experienced by some Prado owners.

On the Prados there is a flap located in the fuel filler pipe at the inlet to one of the
tanks from memory.

The purpose of the flap is to direct fuel into the aux first I think so that it fills first, the reason being the breather pipe goes from the aux to the main and if the main fills first you can't get fuel into the aux as it keeps spitting back due to the fuel in the main tank blocking the aux tanks breather.

This is a common problem and removing the fuel filler hose at the tank and fishing around with a bit of wire generally frees the flap and cures the problem.

I would suggest you visit pradopoint and do some searching on fuel filling issues.

Cheers
Leigh