My truck has always stumbled after sustained low throttle situations and died if it idles for too long. Today was the first nice day we've had since I bought the truck so I traced all the fuel routing (the guy who converted it did some hack work here and there). Long story short, the main tank (ie diesel tank) has no return.

It looks like he took two pollack 6 port valves and routed up everything right except having the return go to the second valve (?) and one return going to the aux. tank and one return deadheading on the vavle (?!!?). BTW, this is with the assumption that the line on the back of the injection pump is the return (forgive me, I'm a newb).

 

Yes, the line behind the inj pump is the return.

It should be set up so the pick up and return are both working off the same tank together.

I.E. Swith in tank A position= pick up from tank A and return to tank A.

Switch in tank B position= pick up from tank B and return to tank B.

If the tanks are plumbed with no crossover line or the crossover valve is closed, you run the risk of overflowing the tank that has the return in it if you start working off the other one first after a fill up.

 

The aux. tank has a return to it, just not the main. It's just a matter of unhooking the return for the aux. from the second valve to the aux. return on the first valve, then plumbing the return for the main tank.....But my main question is still unanswered (which is my fault for not asking it), where does the stock tank return go? From the back of the inj. pump to where on the main tank?

 

top, right at the connections on the fuel module.

You can leave it like that as long as after you fill both tanks you always start with the aux tank.

If you were to start with the main tank, all your return fuel would be going into an already full tank. Get it?

 

I've seen quite a few diesel engines with the return plumbed back into the lift pump inlet.
This works fine except that in cold climates you don't have the return heating the tank fuel and in hot climates you don't have the tank fuel cooling the return.

 

No, I think we're misunderstanding each other. I start the truck then when warm I switch to the second tank. I need to keep the wvo seperate from the diesel, and vice versa

It dosen't make sense to me for the main tank return to just hit a "wall".

I'll have to do some searching for this fuel module.

 

I didn't know you were running a WVO system...

The module it at the top of the tank. Squeeze between the fender and the frame just ahead of the drivers side rear tire. look over the top of the chassis with a flashlight, you'll see it.