Management of auxiliary fuel tank systems

[AnD3rew]

So I have been informed that an auxiliary tank system may increase the risk of water accumulating in the diesel fuel particularly when tanks are left part full and fuel sits for some time at times when you are just using the vehicle around town.

What do people do to manage this? I don't necessarily want to keep tanks full all the time, it is a lot of extra weight.

I am thinking I will fill the aux tank and then pump it Into into the main tank rather than filling the main tank just to keep the fuel fresh and cycling.

Should I invest in a water watch system?

I have also heard that putting half a bottle of metho in he tank ocassionally will help to dissipate the water.

[bbyer]

Here in Canada, we pour small quantities of methyl hydrate, (methanol), into our gasoline fuel tanks at the approach of winter or during the winter months. Small quantities would mean a 150ml bottle to a "tank" of gasoline. By a tank I mean from half to near empty, as in 40 to 80 litres of gasoline - it is not a science. The idea is to soak up any water in the gas tank before it becomes a problem. Ideally the whole process seems like a waste of time and money. You never really want to know that it was needed.

http://www.for.gov.bc.ca/ftp/tch/external/!publish/EMS2/Supplements/MSDS/Gas_Line_Antifreeze_MSDS.pdf

With auxiliary tanks, say located in the rear of a pickup holding maybe 200 litres, I will pour a gallon of methanol in there - again not a science - you are trying to avoid walking in the winter.

As for diesel, I do not know what is used as there are more variables. Some additives keeps the bugs from growing to large; others try to keep the diesel flowing in cold weather and then there is just plain water.

For all that, there seems to be additives that claim to solve all the problems.

http://www.bp.com/liveassets/bp_internet/retail_new/retail_new_australia/STAGING/local_assets/downloads_pdfs/0_999/Fuels_winter_Diesel_Fuel_Additives.pdf

We also have this AdBlue diesel exhaust fluid as well for emission control and that is another variable. That stuff does freeze. Maybe that is why gasoline engines remain popular here.

It seems lots of the fleet pickup purchases are reverting back to gasoline. The overall economics favor gasoline these days - first cost, maintenance costs, fuel costs and resale all tend to favor gasoline in light trucks.

[Lotz-A-Landies]

Andrew

AFAIK the extra tanks for the D3/D4/RRS are placed between the filler and the main tank, you fill the additional tank and as fuel is used by the main tank gravity runs fuel from the additional tank into the main tank. (At least that is the situation with tanks fitted by Opposite Lock.)

It also means that the trip computer stops being accurate and the fuel gauge only reads accurately after the additional tank is empty and the main tank is around half full.

Diana

[TerryO]

Bad diesel fuel is a real problem, we were in picking up our Holden the other day and were speaking to the guy in the service department. Another customer was complaining about is new diesel vehicle running badly out of the blue for no reason.
The service manager then recanted a story about a 18 month old Hyundai that they had just repaired that had got a bad tank of fuel.

The repair bill was $19,000, the car had a new RRP of $38,000.

Chances are around $19,000 was all the Hyundai would have been worth being 18 months old. Lucky or them their insurance paid for it.

He was saying they often get to do jobs on damaged diesel systems. Out here in the country bad diesel fuel contaminated by water is quite common unfortunately. That is the reason I often have said that I regret not buying the petrol V8 D3, just my luck one day I'll get a really bad tank of fuel and the D3 will grind to an expensive halt.

Cheers,
Terry

[Graeme]

Some D3/4 aux tanks are the fill point and gravity feed to the main tank but others use a 2nd filler and a transfer pump.

[Redback]

We fill both all the time, ours is gravity feed, so no pump, fuel goes through the auxiliary tank to fill the main.

Baz

[AnD3rew]

Mine uses a pump to pump the fuel from one to the other manually.

[mowog]

When I fill, I fill both. It hurts the wallet but I don't do it that often. I have the LongRanger with the electric pump. The trip computer updates distance to empty after the transfer.

[Geedublya]

Around town driving.

I run my main tank down to near empty (500km) then pump aux tank into main until it is full on the gauge. At the 1000km mark I pump the remainder of the aux tank into the main, It is obvious when the aux tank is empty as the aux pump gets very noisy. I then fill both tanks at between 1100 and 1200km about $230.

I have a filter between the aux and main tanks and change this every second service (20K). Last time it had about 5ml of water in it. I change the main fuel filter every second service as well and drain it every service.

On a trip I do the same except I use the scanguage distance to empty guide me on when I need to fill up.

[Lotz-A-Landies]

We fill both all the time, ours is gravity feed, so no pump, fuel goes through the auxiliary tank to fill the main.

BazI have been wondering if you put a fuel shut-off solenoid valve between the two tanks and fill with the valve open then shut the valve would it solve the computer errors?

You then open the solenoid to top up the main.

[Tote]

I always fill both tanks and transfer from the second tank when the fuel light comes on. The number of KM I do means that the fill up period is a bit less than fortnightly.
If I was parking the vehicle for I while I would top up both tanks as the risk of condensation in the tanks is then reduced.

Regards,
Tote

[Redback]

I have been wondering if you put a fuel shut-off solenoid valve between the two tanks and fill with the valve open then shut the valve would it solve the computer errors?

You then open the solenoid to top up the main.

What computer errors Diana:confused:

Baz.

[Lotz-A-Landies]

What computer errors Diana:confused:

Baz.The computer distance to empty and fuel usage/ecomomy readings are in error.

It's the OL gravity fill tank I'm talking about. You fill the auxillary tank which fills the main tank and keeps it topped up so the computer recognises the fill but not the extra fuel that keeps draining into it. The fuel gauge on the dash also stays full until the aux tank is empty.

Or am I very wrong?

[Redback]

The computer distance to empty and fuel usage/ecomomy readings are in error.

It's the OL gravity fill tank I'm talking about. You fill the auxillary tank which fills the main tank and keeps it topped up so the computer recognises the fill but not the extra fuel that keeps draining into it. The fuel gauge on the dash also stays full until the aux tank is empty.

Or am I very wrong?

Ours is wrong anyway, actually it's always been wrong even before we got the auxiliary tank, last time I filled it,(both tanks) distance to empty showed up as 435k, it's never showed anywhere near what it should show.

The gauge stays full until the auxiliary is empty, yes, but I always knew that would be the case and I don't mind that, this means it tells you that you have another 600 to 800ks left depending on whether your towing or offroad, great if your remote and fuel stops are not as regular, one thing I did notice, once the fuel gauge starts to drop, the distance to empty rises, then drops as you get closer to half, that tells me the computer is not very accurate, but according to Purnells that's OK and it's all the accessories that is the problem, they are causing all our fuel problems, including economy:twisted:

I know there is a problem, because we have been getting the same economy since we bought the car, before and after fitting the accessories, trouble is knowone will listen, we had one dealer in SA that said there was a problem and he even argued the point with LRA, but the dealers here reckon he's wrong and the accessories are to blame.

So the OL tank is fine, the only error is if I don't fill the car properly, it needs to be filled to allow air pockets to clear, you do this by listening for the air escaping to stop then keep filling, we didn't want a tank with a pump, just something else to fail and they do fail on a regular basis, not something you want to happen in a remote area.

Baz.