Auxiliary tank use question (1 Viewer)

[axel64]

Hi all,

I just purchased a 1999 HZJ75 with an 140L auxiliary tank. I just don't understand how it works and seek some help.

The seller told me that there is a transfer pump with which I can transfer fuel from the 140L auxiliary tank to the 90L main tank. The switch sits under the dash and I have to manually engage it to pump fuel from aux to main tank - or so I was told. The pump worked when I purchased the car, but the 2. tank was empty when I tested the function of the pump. Later I filled up the main tank and used it. A couple days after that I filled up both tanks and the vehicle used the fuel from the auxiliary tank only - without me engaging the transfer pump at all. So I am wondering what kind of setup this is and what happens when the auxiliary tank gets empty. Will the main tank automatically be used and if so, how? As I said in the beginning: the main tank was used when the auxiliary was still empty after the purchase. But how can it be that only the auxiliary tank is now used when both tanks are full? I don't understand this. Can anyone give me their two cents worth, please?

 

[Tennessee Jed]

I don't know but it sounds like you have one of the several different after market aux fuel tanks like those sold by Long Ranger etc.

Assume that it works. Don't expect it to be broken. With both tanks full it's going to be hard to judge the pumping action. Fuel pumps are mature technology and should be pretty dependable.

But pumping fuel into a main tank from a secondary tank is not unusual. Same with water.

 

[tmarx]

Sounds more like you have a "switch over" solenoid type system than a transfer pump system.

Pics would help