Injector Return Line Pressureising ang Blowing off.

[Sorro71]

I bet the solenoid was added to combat air intrusion in the system. It would keep the fuel from draining back to the tank as the air leaked into the system.

That's what I was leaning towards. I've never had air intrusion problems, even when the caps did leak a lot. Thinking back when I first bought the truck every storage compartment in the cab had those plastic caps, o'rings, clamps and bits of hose in them. My guess is the PO had a tuff time with air intrusion and came up with the solenoid idea.

 

[OLDBULL8]

I bet the solenoid was added to combat air intrusion in the system. It would keep the fuel from draining back to the tank as the air leaked into the system.

Now that I can see the return lines clearly, I agree with the above quote. That's what I first thought. The PO must of had drain back and thought the solenoid would fix it. Maybe it did. Looks to be big enough as long it has at least 1/4" flow thru, 5/16" would be best. There is usually 1 or 2 PSI thru out the return system due to line resistance to tanks. No harm keeping the solenoid as long as it don't blow a fuse or coil burns out, if either would happen then the return system would build pressure and the engine would shut down.