Fuel from sub-tank going into main tank

[apaul Lurker Find all posts View Profile Close apaul]

Hi All,
We have a 2000 Prado diesel. We are having a strange issue with the sub-tank.
When I use the sub-tank , the fuel is getting transferred to the maln tank.After 75-100km, the sub tank becomes empty and the level in the main tank has increased.

I have verified this multiple times. Spoke to two mechanics and they have no clue about it. One person said , it could be a sticky solinoid,

Does anyone has come across this issue?

Thanks,
Aji

[amts Ninja Poster. Find all posts View Profile Close amts]

Isn't that how they work?

[sparksy Senior Member Find all posts View Profile Close sparksy]

Isn't that how they work?

Not in the 90 series. The 1998 model I had the tanks were switchable via a switch on the dash. Could run on either tank. But for some reason the returning fuel seemed to end up in the sub tank so it did seem to rise over time if not used. opposite to what OP is observing.

https://www.pradopoint.com.au/forum/.../3741-sub-tank

https://www.pradopoint.com.au/forum/...w-do-they-work

[carco Advanced Member Find all posts View Profile Close carco]

90 series diesel has twin solenoid valves, one for fuel to engine and the other for return to tank.
When working properly, bleed back fuel will be returned to the tank you’re drawing from.
When one solenoid fails, return fuel goes to whichever tank the solenoid valve has left open, fill that tank and then flow across to the other tank as the 90 has that “Y” pipe arrangement at the fuel filler.

[Yowie_In_Oz Lurker Find all posts View Profile Close Yowie_In_Oz]

If you notice fuel transferring between tanks it will most likely be a faulty return fuel solenoid.