GU Sub-Tank on a diesel.

[terreyhills9]

Hi,

I have only had my GU for about a month and the the Sub-tank has never been used. The previous owner advised that he never had any need to fill the tank.

Is anyone aware if I need to do anything prior to filling it up as it has not been used since the truck was new which is approx 6 years?

Thanks to any one that can help.

[threedogs]

You should never drain them and leave them empty as seals dry out,
I'd put 20 litres in it for a day or so then see if it will transfer over to the main tank.
Hopefully your fuel lines wont be perished from lack of use

[Bigcol]

mate, I would suggest next time your at the servo - put $5 or $10 in........................... DONT fill it yet
thee GU's have a peculiar thing with their factory sub tank
when you start the car - if there is fuel in the sub rank - the system "self primes" it will pump a small amount - 200 to 300ml into the main tank, to make sure it is working
if it dont work - a light on the dash for the sub tank will turn on
NOT the light on the button for the sub tank - but close to where you seat belt / Air Bag warning lights are
if that lights up, you know there is a problem with the sub tank.

its always handy to have - and better to make sure its working, than to fill it one day, and find you have no way of moving the fuel out of it to fix a problem if there is one

always handy just to put $5 in every time you fill it, as sooner or later you will fill it

cheers

[threedogs]

Totally agree always have some fuel sloshing around, I have 95 main and 75 Aux tanks
and once every month and a half I fill both then as main gets to 1/4 I'll pump from aux to top up main.
Its never empty the aux always at least 5ltr in it. plus if inside of tank dries out flakey bits from inside
of tank may clog pump or filters

[terreyhills9]

Thanks threedogs & Bigcol that really helps.

I will be filling up later today and will fill it with $5 worth and see what happens.

I will let you know how I go.

Cheers.

[the evil twin]

Totally agree always have some fuel sloshing around, I have 95 main and 75 Aux tanks
and once every month and a half I fill both then as main gets to 1/4 I'll pump from aux to top up main.
Its never empty the aux always at least 5ltr in it. plus if inside of tank dries out flakey bits from inside
of tank may clog pump or filters

Great minds, matey...

I do exactly the same only diff is I have a 145 main and 30 aux, I always fill both, run the main down to 1/2 ish, pump the aux across, run some more, fillup both and start the cycle again.

Even if I am filling early because of price or a trip I'll usually empty the aux into the main or as much as will go and top up both

[terreyhills9]

Great minds, matey...

I do exactly the same only diff is I have a 145 main and 30 aux, I always fill both, run the main down to 1/2 ish, pump the aux across, run some more, fillup both and start the cycle again.

Even if I am filling early because of price or a trip I'll usually empty the aux into the main or as much as will go and top up both

Thanks 'the evil twin' sounds like everyone has the same opinion.

Thanks for your help.

[Morton]

yes I do the same, mine are standard but fill both, drive main till half empty & pump across from aux tank, keeps everything working nicely, haven't had an issue in 8 yrs

[macca]

Terry on the ute I have this is what happens.... if you have a look in the main tank filler tube there is a flow of fuel from the sub when "self priming", doesn't flow for long.

If you can see that it is a good start, then try turning the transfer pump on and the flow should be seen in the same pipes.

My transfer runs at about 1 litre per minute, it is slow.

Hope you find it is all good on yours