Primary fuel filter valve question

[MarioG]

I have this amazingly stupid question that I need answered. What exactly is this valve and pipe for? Where does it come from? It's on the suction side, downstream of the Dhal filter. Line above this valve goes to the secondary filter on the engine. Is the valve supposed to be open or closed? I don't get it and can't find it in the factory schematics

I gave myself a brain fart. Please help clear this up so my OCD won't keep me up all night.

Thanks

Mario

 

[Avenger]

"Suction side" is a little ambiguous. But usually a valve like that is closed while you are changing a filter element so the fuel system doesn't bleed down when you open it.

 

[MarioG]

"Suction side" is a little ambiguous. But usually a valve like that is closed while you are changing a filter element so the fuel system doesn't bleed down when you open it.

If that's the case wouldn't the valve be on the supply side (the other tube on the right side of the filter).?

 

[johnjen50]

Is it the cross over line between the engines? My YF set up is different than yours but I bet that's what it is, so you could draw directly from that tank to the other engine secondary. Where does that line go that looks like it leads to the manifold? Does it or does it just go through that box and down under the floor to the other engine room. Mine does that only its a line connecting the two secondaries.

 

[Avenger]

If that's the case wouldn't the valve be on the supply side (the other tube on the right side of the filter).?

One would think. But it could depend on height and the position of filter in relation to the engine and tanks too. Johnjen50 may be on the right track but it seems on odd way to do tank selection.

 

[Glory]

Follow the line, see where it goes!

 

[MikeP]

Follow the line, see where it goes!

There you go!

But FWIW, I'm wondering if it might be a feed to the Genny, though that's commonly a separate tube from the tank itself.

 

[MarioG]

Mystery solved! !!

After stepping away from this thing for a day to relax, I returned and hunted down the fuel lines. The result is that the tee in line I am pointing to in the picture is directing fuel up and over to the priming pump and from there to the secondary filter. The line going down from the tee past the valve pictured is going directly to the engine fuel pump.

I don't understand why but that's what's there. Either way, it's all coming out of there and being replaced with racor 1000's with it's own priming pumps and all new fuel valves.

Thank you all for the help.
Mario

 

[Avenger]

I'd suggest keeping the Dahls. They work just as well, but they don't trap air like Racors.