Outer Limits 4x4 Board

Hi all

i have a unique set up that i cant get my head around.

In my engine bay on the tube between fuel filter and fuel injector pump i have a T section that had a tube coming off it that dissapears into drivers side firewall.
and on the return line from the fuel injector pump i have an valve currently in open position i have never seen this before.





as you can see it is a very strange setup has anybody seen anything like this and able to shed some light on it

also i think this might play into it somewhere



lines at top of pic go to sub tank.

as you can see with the solenoides they just loop the sub tank fuel so in fact its competely isolated.

lines from main fuel tank now completely bypass the solenoids

got the engine bay sorted out.

that T section goes to a pressure gauge that previouse owner told me was for an old compressor

and the valve surves no purpose but to blow the line off the fuel pump lol so it can all be safetly removed.

still not sure with solenoids in rear for sub tank tho