WVO Question about system.

[Jerry32]

Why can't you have just one fuel line to WVO Tank for both directions? Why waste the heated oil back to the tank when you could just as well feed it back to the intake of the system. Then when you switch to D the purged fuel will go right back in the WVA tank until done then switch to fuel tank return line. Jerry

[wal1809]

Hello Jerry.  I was going to do a return fuel to the wvo tank.  I changed my mind for the loss of all heat as it hit the wvo tank.  So then I decided on a closed loop system, directing the return fuel to the main wvo line.  I fought it but changed my mind mainly because of air.  On a closed loop if you get air, which you probably will, then it goes through the loop over and over again.

At the direction of another busnut I decided on a small 20 gallon fuel tank near the motor and the 100 gallon wvo in the front bay.  That way I can heat the 20 gallon tank easily,  return the fuel to it as well so air would not be a problem and I could fill it from the 100 gallon tank with the flip of a switch at the driver seat.

It also stops the greater vaccum the engine fuel pump would create from pulling wvo 30 ft through the fuel line.

[Jerry32]

I would think that thee air bubbles would work there way out through the injectorss Jerry

[wal1809]

No air wil go though The rack over and over again and it will run rough, try to die or die all together.

[Jerry W Campbell]

It is my understanding that on the two strokes as the fuel passes thru the engine and reaches the return line, there is an orifice or hole or jet of a certain size to create a certain amount of back pressure that the injectors need to function properly. The return line must be free flowing for this to happen. If this is true then it seems that looping back the return line would not work. Thats why I did not attempt it.
BUT, I've been wrong before. Once, I think.
Jerry

[JackConrad]

8V71 uses a fuel restrictor fitting in the fuel return circuit with a .070 orfice. I just picked up a new one yesterday at Covington DD in Greensboro, NC. Total price with tax was $6.30.  Inline 6-71 book calls for a .080 orfice.  Jack

[wal1809]

It is my understanding that on the two strokes as the fuel passes thru the engine and reaches the return line, there is an orifice or hole or jet of a certain size to create a certain amount of back pressure that the injectors need to function properly. The return line must be free flowing for this to happen. If this is true then it seems that looping back the return line would not work. Thats why I did not attempt it.
BUT, I've been wrong before. Once, I think.
Jerry

The return fuel must Tee into the main line after the restriction.  Therefore it will worki.  Teeing into prior to that it will not work.

[luvrbus]

If I were you guys running WVO I would go with the new style DDEC fuel pump on a 2 stroke it supplies fuel to both heads at one time doesn't make a loop just a idea for you guys.
I use the pump for replacement for the old pumps.,it is higher pressure and volume both and fwiw I don't use a orifice with the new style pump

good luck

[Jerry32]

What are you guys using for the fuel pump as I am not wanting to run WVO through the diesel filters so would need an electric pump 60-80 lbs pressure to operate the system Jerry

[wal1809]

I am running diesel through the factory installed system.  Wvo through it's own primary filter then into the factory secondary.  To do the way your talking about you will need three valves. What are your reservations about using the factory secondary for both diesel and wvo? 

The way I see it The wvo is dewatered before the filters on my wvo processor.  Then through. 5 micron filter before settling for what could be months.  Drawing off the top the oil goes through  a 2 micron filter and on into the bus tank.  From there it will be pushed through a 5 micron into the surge tank.  It will drawn by engine vaccum fuel pump through another 5 micron then pushed through the secondary diesel filter.  Any number if the previous filters will plug long before the factory filter.  I intend on keeping a dozen or more filters with me at all times and switching the wvo praties quite often just for shizzles.

[Jerry W Campbell]

It is my understanding that on the two strokes as the fuel passes thru the engine and reaches the return line, there is an orifice or hole or jet of a certain size to create a certain amount of back pressure that the injectors need to function properly. The return line must be free flowing for this to happen. If this is true then it seems that looping back the return line would not work. Thats why I did not attempt it.
BUT, I've been wrong before. Once, I think.
Jerry

The return fuel must Tee into the main line after the restriction.  Therefore it will worki.  Teeing into prior to that it will not work.

You can't get to the return line until it leaves the motor which is after the restriction. The question is if you Tee into the fuel line before the pump,  the pump is going to be sucking on the return line. Is this suction going to affect the back pressure in the motor because the return line is no longer free flowing it is being sucked.
Jerry

[wal1809]

I think I see what your asking but making th system with the return fuel going straight to a tee right at the pump doesn't make sense to me.  The closest you would want to put it ( the tee) is behind your heat exchangers. 

Would doing it the way you described cause a vaccum problem?  I don't think it would.  Essentially at the tee there would be a 1 inch wvo feed.  .5 from the wvo tank and .5 from the return feed.  I don't see it causing a problem other than air in the loop.  If, actually when you get air in the loop you have to get it out.    Air will go through the rack, cause whatever problem it will cause, go to the tee and cause the same problem over and over until you get the air out.  With returning to a smaller surge tank you wipe out the need to clear the air forever.  It will bleed itself off on the first return to the surge tank.

I siad it in another post, I did not understand the need for a surge tank when first told about it.  Now it is all the rage in my book.  It solves a whole lot of problems and allows me another 20 gallons of fuel.

[Jerry32]

Seems like pretty low sucktion since there is a feed line there too. How do you hadle keeeping the surge tank full or resupplied? I am not clear on this as I see it as the vo being sucked into the surge tank and then do you need to bleed it to get it full? Jerry

[Jerry32]

I don't want to use the final diesel filter as if it becomes plugged you wouldn't be able to switch back to diesel and would be in a bad situation. I want to be able to go on without delay and find a convenient spot to stop  and change filters. Also it is not heated and is low on the bottom side of the engine area and would get cold air wqhen traveling in winter. I would be nice since it has two fuel lines out , one to each head. Jerry

[wal1809]

Hello Jerry 32.  First I need to inform you of fact.  Fact, I am like you, in th emiddle of the conversion.  I have not run the bus on wvo as of yet.  The information I am getting is from fella busnuts that visit here from time to time and other I have known for years.  Now so far as bio diesel I can say I have been to that cave and seen the critter inside.

In the last post I spoke of the final filter.  Prior to reaching that filter you should have the oil down to 2 micron and no water.  On my system it will plug 1 of 4 filters prior to entering the final filter which is usually 10 micron.  If you switch all these filters on a regular basis you should not have a problem.  Also when filters plug they are not usually an on and off situation.  When it begins to plug you will feel it lose a little power at first and gradually get down to plugged.  I have never had a filter just lock up on my vehicles.  I do routinely change the filters.