Improved sub tank transfer rate.

[Cuppa]

Another little win hard on the heels of my improved fuel consumption.

As long as I’ve had the car the transfer from sub tank to main tank has been quite slow, but I just accepted that this is how it was designed to be. Also whenever I have removed the sub tank filler cap it has always hissed a little, sucking in air.

Yesterday I finally investigated. I tried blowing compressed air through the breather tube into the tank & wasn’t too surprised when it became obvious there was a blockage. Having discovered this I started pulling secions of pipe off one by one, expecting to find a mud wasp nest or similar. The blockage turned out to be right at the end of the pipe right against the spigot on the top of the tank. Unable to push it out I had to cut off the end of the pipe. Finally exposing the cause, it turned out to be one of those little plastic protectors which come on the end of ockie strap hooks! it had a tiny hole in it, which is probably why the tank hadn’t collapsed from a vacuum. How on earth it got there is anyone’s guess! I know when I first looked at the car the sub tank had a leak, & the tank was replaced by the car yard before I bought it.

Now when transferring fuel from sub tank to main tank, the fuel gauge rises probably twice as quickly.

[BigRAWesty]

Nice one.
I too have noticed hissing when taking the cap off. I may have a did too see what I can find

[mudski]

Something i have to investigate too. Both my tanks hiss when I open them up. I checked the breather that sits up in the rear guard and it was good. I didn't really go any further with it TBH. So there another small pipe I need to look for....

[threedogs]

Mine does as well I think its normal as my other 4x4 did it as well,
surely not all have a blockage lol
Mine also transfer fuel very quickly.IMO

[clubbyr8]

Both my tanks hiss as well and it seems it takes forever to transfer the fuel, well over 30 minutes....

[jff45]

I was pretty sure mine always hissed when unscrewing the caps so I went out to the shed just now to try it.
My car hasn't been running for 3 days but they both still hissed anyway so I have no idea what it is..

[Robo]

Has someone forgot to remove the protective caps off the tanks before install ??.
Not you cuppa,
But you have given me another thing to look at.
Pat also seems to take 30 mins to take a leak!

[Cuppa]

Has someone forgot to remove the protective caps off the tanks before install ??.

Don’t think so, the replacement tank was removed from another ex Telstra Patrol, besides which the open end of the little cap thingy causing the blockage was faced away from the tank.

[the evil twin]

snip...
it turned out to be one of those little plastic protectors which come on the end of ockie strap hooks! it had a tiny hole in it,

Perhaps some numpty decided that he only wanted a pin hole breather and deliberately put the "bung" in the breather.
They can get a fair bit of pressure differential so maybe the tank breather sucked in the bung till it jammed.
Maybe he was having condensate issues or whatever
It's a longshot but I have seen people do really stupid shit over the years... especially a really ugly bloke I often spot in the mirror

P.S. the factory pump should transfer at 1 & 1/2 LPM.
To work out if the pump etc is OK empty then fill the sub, note the Litres and do the following
Litres added times 1
Divide that by 2 and remember for later
Litres added divided by 10
Multiply by 5 and remember for later
If it is a Diesel set your watch forward 7 minutes unless you disconnect the battery
If it is Petrol leave watch as is but deduct 172 seconds if it is a 4.8
Turn ignition on then off 3 times quickly then once slowly (do not start engine)
Forget what you remembered and if the tank transfers 30 litres in 20 minutes give or take or 70 litres in 45 minutes give or take it is probably OK

[Cuppa]

Do you have a pommy or Scots hetitage ET? Numpty?