3 way valve connection

[EricN]

Got my plant drive kit the other day and finally started looking at how to connect it. I didnt get any instructions for the 3 ports so I made one up in my head that seemed to make sense. Plantdrive people then sent me a "how to" with their method of hooking it up. I am curious if anyone with any experience would know why my idea wouldn't work.
Keep in mind that port 2 is common and 2-1 are connected when the solenoid is not energized. I have the fuel looping right back to the feed rail before vegtherm. Any input is appreciated. I just think their system of doing it makes for alot of extra fuel line and cross contamination. Plus as a bonus, I get an easy bleed port for the vegie side.
p.s. Since my pic is going to be a red X when I look at it, can someone tell me if it works for them.

[josh]

It's not how i put mine together... but who knows... are you sure you wont build up to much pressure in the lines by looping it that way? i honestly am not looking at it to hard as my wife is calling for me to get my butt in bed... but I will look at it tomorrow and tell you how I plumbed mine.

And where does your return run? I am slightly confused by that.

Josh

[docsavage]

Hi Eric,

I don't think the valves will work the way you have them. The return line has to go back to the tank. As I recall on Josh's we used one valve for the fuel in and one for fuel return. I believe we did it this way, and Josh will clarify -

Fuel In Valve: Diesel in port one, veggie in port 3, and out to the injector pump from 2

Return Valve: Return from injector in port 2, diesel out port 1, veggie out port 3. Both outlets return to their respective tanks.

Good luck.

James

[EricN]

Plant drive did send me the instructions finally for the 3 port but only after I thought this one up. So I was trying to figure out why my way would not work. There has to be a reason because it is too simple and yet it is not used. I dont have any return to the tanks, just a loop back to the supply line. I will probably end up hooking it up normally (1 valve supply, 1 valve return) but I would like to know why. As for pressure building up, I dont know much about diesels but I suspect that the return line would not have too much pressure, 10 lbs maybe? Which is what you would find if there was an electric lift pump before the injection pump. Any opinions welcome.

[docsavage]

I'm guessing here, but I think that with the return looped under higher pressure than the suction side, there would not be enough suction to draw fuel from the tank and would just drive fuel back to the tank and result in no fuel to the engine. Otherwise the factory would loop the return line into the intake line not to the tank.

James

[EricN]

I just got an email from Ed at plantdrive. He said send the SVO as a loop back to the intake and send the diesl back to the tank. The only issue I can see with a constant loop is maybe air getting trapped may have a hard time getting out of the system. Switch to diesel and the air is sent to the tank.

[josh]

I believe we did it this way, and Josh will clarify -

Fuel In Valve: Diesel in port one, veggie in port 3, and out to the injector pump from 2

Return Valve: Return from injector in port 2, diesel out port 1, veggie out port 3. Both outlets return to their respective tanks.

James,

I do believe you are right, I am just not sure about the numbering... which valve was the open and closed and so forth... but your way is right assuming the valves were numbered in that order. (I dont want to try to pull mine out and cram it back in to take a look at the numbers... it takes a solid hour at least).

Eric,

I have nothing looped... everything is run back to the tanks... veg to veg, dino to dino... although I do get a light bit of cross contamination when switching fuels. That can be switched easily by getting a three way switch though so that one of the solenoids (the one controlling the returning fuel) is delayed from switching... and that way the only cross contamination happens in the veg tank (a bit of dino in the veg only helps thin it out).

Switch to diesel and the air is sent to the tank.

It wouldn't just be the air, it would be whatever veg is still in the lines... wouldnt that be right? I mean all the fuel is not used up. But then again what do i know.

Good luck.
Josh

[EricN]

James' numbering is right (for my valves). I know the proper way now, I am just wondering why not the way I have shown.
As for my air to the tank comment, I mean that if air is in the system from changing a fuel filter etc., if there is a loop to the feed instead of a return to the tank, the air might have a hard time purging itself from the system?????? So if you run veggie on the loop and diesel to the tank, then I guess you could purge the air out through the diesel side and still use the veggie in a loop so it gets warmer.
This is just me trying to figure out the negatives of it. I have no idea if I am right. For simplicity sake, I am going to hook it up the same as everyone else.

[josh]

Eric,

Talk to a Diesel mechanic if you think it will work. I mean you never know, it might be a brilliant idea. I wish I could be more help, but I just have this nagging thought like it would build pressure... if you do ask keep us posted, I would be curious to know. It would help with heat, and cut down on hose.

Josh