Outer Limits 4x4 Board

is there any way of stopping the sub tank from pumping fuel into the main tank everytime the car starts?
i would prefer to just use the main tank and when that goes empty then use the sub tank.

j-top paj wrote:is there any way of stopping the sub tank from pumping fuel into the main tank everytime the car starts?
i would prefer to just use the main tank and when that goes empty then use the sub tank.

fuel pump in the sub with a switch, GUs are gravity fed to the main feed tank

it wont confuse the computers or sensors etc???

j-top paj wrote:it wont confuse the computers or sensors etc???

Havn't done it personally but have seen it. Dont know of any implication with computors, but if you are switching between I couldnt think of any

I've got a 1998 GU and dont have that problem of the tank automatically filling into the main tank when i start the car. I've got a button on the dash which was standard so i can stop or start emptying the sub into the main.

in the manual it states that the sub tank will automatically pump fuel into the main tank each time it starts the engine.
if you listen when you turn the reds on, listen to under the sterio and after 5 seconds you will hear a click. this is the module for the sub tank control.
i have the switch too.

ive heard that clicking noise and thought my dual battery system was playin up but yeh on my 98gu everytime i star the engine a little bit of fuel goes from sub tank to main but i also have the on dash button that allows me to pump the whole from the subtank to the main in one hit!

i noticed it when i was putting in extra power sockets. its a little module that says sub tank or something.

would be good if we could switch from tank to tank instead of having to pump from one into the other.
makes it easier to know exactly how much fuel is used for the amount of Ks.

Tiny wrote:

j-top paj wrote:is there any way of stopping the sub tank from pumping fuel into the main tank everytime the car starts?
i would prefer to just use the main tank and when that goes empty then use the sub tank.

fuel pump in the sub with a switch, GUs are gravity fed to the main feed tank

you must park on big hills, my tanks are the same height.

I thought the reason the pump turns on for the first few seconds was to help keep the pump in good condition Ie. the seals and such...

GUJohnno wrote:I thought the reason the pump turns on for the first few seconds was to help keep the pump in good condition Ie. the seals and such...

good point,
maybe i should just leave it.

Makes no difference. Fill both tanks. Drive, refil both tanks. Calculate fuel consumption.

Would imagine as above it is to keep the pump in good nick.

(Sort of thing a lot of after market gear forgets to do!) LOL

old thread i know.
but it would also stop the fuel in the sub tank going stale if never used and stops any chance of the lines gumming up etc

i was looking into it a while ago for mt old mans GU, you can get a switchable "unit" to switch between tanks, ive lost the link over time but you do have options,

factory sub tank runs for 5 seconds evry time to start the truck, if youve noted how long it takes to pump the sub over 5 seconds isnt moving much fuel at all,

at a guess id also say its not ery good to leave the sub tank empty, as the pump will run dry,

the sub tank uses a low level indicater to shut down when empty. and a full indicater in the main to also switch off (when full). this system suffers from the lack of a earth strap from the body to the chassis, this is easly over come by fitting a winch. or just fit a strap from the chassis to the body, a good spot is near the steering box, from the battrey lead body point to the 6mm threded hole in the chassis. this over comes the lack off earth return wiring on spot lights, etc. as they will earth back through the sub tank wiring and shut down the module. (if not earthed) hope this helps, cherrs Phill.

Unless the subtank has a high pressure pump (for petrol) i think it needs to pump to the main so it will feed the engine - ie no direct feed from sub to engine ?

GUHohno has got it right along with patrol man. The pump simply runs for a short while to keep the seals wet and lines clear(ish). It won't run itself dry due to low level sensor (which switches pump off if you transfer all of the fuel).
If ain't broke...

I would agree of this "lubrication" principal, and not alter anything, or you might be up for a new pump in the future.
Slightly off topic, but......
I have also wired up my air conditioning compressor to come on ( without the idle up) when I put my patrol in reverse, to keep the seals and lubrication system in good condition, using the same principal, because a/c is hardly used in Vic, and the compressor eventually will fail if unused.
I got the idea from an early pulsar, they are set up this way as standard.