Fuel lines inside the diesel tank. Return line vs vent. Which is which?

[advlars]

Hey guys,

Dropped my tank today to check the condition inside and have a question about the lines. 85 pickup/hilux but Id imagine the configuration/concept is the same on a diesel cruiser.

On my tank there are two hardlines that go all the way to the bottom of the tank, through the removable cap and one that enters seperately though a welded on nipple and doesnt extend any lower than the top of the tank.

I labled my lines when I removed them but Im thinking the PO might have had them mixed up to begin with. My return line appears to connect to the welded on nipple (and therefore dumps fuel from the tippy top of the tank) and my breather vent extends all the way to the bottom of the tank next to my suction line. Is this correct? Cause it seems to me it should be the other way around.

fwiw I sometimes get a hiss when I open the fill neck, and Ive had a persistent problem sucking air from the tank. Im wondering if this configuration is making 1) the tank not vent properly and 2) the extra height of the return squirting in is "aerating" my diesel like the little waterfall aerators in a fish tank.

Cheers,
Lars

 

[roscoFJ73]

and my breather vent extends all the way to the bottom of the tank next to my suction line. Is this correct? Cause it seems to me it should be the other way around.

I think so, breathers are only there to vent gas. A little pressure in the tank is normal. All 5 Landcruisers and Dynas that Ive owned have hissed .

Pics would help. Follow the lines back from the injector pump. Check the manual.
I don't think the aeration is a problem. It would aerate much more when driving and even more offroad. Ive seen fuel in see through tanks on some engines and the fuel is like a milk shake, even at idle.

 

[advlars]

Hey rosco, just to clarify when you say "I think so" you mean you agree they should be switched the other way around? i.e. return line goes to the bottom and breather only goes to the top of the tank?

I tried the manual but couldnt find what im looking for. My 85 pickup manual only has stuff for the 22re gasser and my supplemental diesel manual for the 2lt engine doesnt have anything about the diesel tank. Perhaps tonight I can find a copy of an aussie service manual or something...

you might be right about aeration not being a thing. Ive vacuum tested EVERYTHING and I cant find the source of the leak for the life of me.

 

[roscoFJ73]

just to clarify when you say "I think so" you mean you agree they should be switched the other way around? i.e. return line goes to the bottom and breather only goes to the top of the tank?

I'm not there to see it so I can only guess, but it does sound like it needs to be switched around. A vent tube doesn't need to be a the bottom as its there to vent vapour.

my supplemental diesel manual for the 2lt engine doesnt have anything about the diesel tank. Perhaps tonight I can find a copy of an aussie service manual or something...

It shouldn't be too much different to any other Toyota diesel.
I would post up some pics, maybe the LJ7* owners have an identical fuel system