[airfooter]

I need some clarification. Do the checkvalves at the end of each fuel line, at the heads, prevent fuel from leaving heads? /ubbthreads/images/graemlins/shrug.gif

Specifically, if I introduce WVO from the opposite side of each head, will WVO be prevented from going to factory fuel filter (and beyond) because of these 'valves'? Or do I need to add a 'real' CV to the factory system?

Since these appear to be eliminated during Regulated Return modification, maybe somebodys got a couple somewhere they could check for me. Or a part # so I could try to go see one? /ubbthreads/images/graemlins/shrug.gif

 

[Richter69]

Its not a total seal deal, they are there to prevent the fuel spikes from the splits from getting into the filter housing and fuel pump.

 

[klhansen]

[ QUOTE ]
I need some clarification. Do the checkvalves at the end of each fuel line, at the heads, prevent fuel from leaving heads?

Specifically, if I introduce WVO from the opposite side of each head, will WVO be prevented from going to factory fuel filter (and beyond) because of these 'valves'? Or do I need to add a 'real' CV to the factory system?

Since these appear to be eliminated during Regulated Return modification, maybe somebodys got a couple somewhere they could check for me. Or a part # so I could try to go see one?

[/ QUOTE ]

I think they're true check valves that prevent fuel from leaving the head.

When I took mine out, I recall trying to blow thru them backward. If I remember, I'll double check this PM.

I suppose if you used the same type of system for your WVO feed, you could just shut off one or the other of the fuel supplies and flush the fuel rails in the heads out with the "active" fuel.

 

[DIESELSITE]

They "suppress" the reverse flow. They do not stop it. They allow just enough to still be able to control pressure. This helps maintain steady fuel pressure in the heads from fluctuations caused by the injectors. These were only installed on "dead headed systems".

 

[longroundtip]

They are not true check valves. I installed the return reg mod but I did not remove the "check valves" in my truck. After the truck has been sitting for several hours the fuel pressure drifts down from 70 PSI to nothing. There are no leaks, so the only way to get that kind of pressure drop is if the fuel is leaking through the "check valves" in reverse, through the filter bowl and back through the pump to the tank.

A true check valve would only let fluid flow one direction.

 

[airfooter]

[ QUOTE ]
They are not true check valves. I installed the return reg mod but I did not remove the "check valves" in my truck. After the truck has been sitting for several hours the fuel pressure drifts down from 70 PSI to nothing. There are no leaks, so the only way to get that kind of pressure drop is if the fuel is leaking through the "check valves" in reverse, through the filter bowl and back through the pump to the tank.

A true check valve would only let fluid flow one direction.

[/ QUOTE ]

Did you install the "return" lines in the rear of each head? and supply from the front? IOW, are you flowing fuel the 'wrong way' through one of the factory CV's? Or did you leave factory supplys in place and return thru oposite side of head?

My fuel pressure drops also (all stock) but I have know way to tell what is happening 'in the head'. Couldn't your press drop be thru regulator or somewhere else?

I'm having a hard time understanding a 'partial' check valve. /ubbthreads/images/graemlins/shrug.gif

Seems like the factory CV's would be there to keep fuel in the heads and prevent a 'dry' start.

I would love to hear from someone who has one of these in their hand!!

[ QUOTE ]

I suppose if you used the same type of system for your WVO feed, you could just shut off one or the other of the fuel supplies and flush the fuel rails in the heads out with the "active" fuel.

[/ QUOTE ]

Yes, there will also be a CV on the WVO side. Between that CV and heads will be a purge solenoid that will return to WVO tank allowing faster purge times. /ubbthreads/images/graemlins/smokin.gif

 

[airfooter]

Can someone with one of these 'check valves' out please check it out for me?

/ubbthreads/images/graemlins/grin.gifBIG thank you!!

 

[Minnesota]

Jason, Do you have another thread somewhere describing your WVO set-up? I was not aware that our trucks could run straight WVO. TIA.

 

[DIESELSITE]

SkySkiJason, I'm not speculating. I've had several hundred in my hands, besides all the ones I dissaembled. They are not check valves.

Secondly, you don't want pressure to stay in the heads after shutdown in the case an o-ring on the injector failed, you'd flood a cylinder.

Thirdly, upon turning on your key, you have full pressure to the injector before you even crank it. There is no such thing as a dry start, unless you personally/ purposely emptied the rails, then immediately tried to start it.

[ QUOTE ]
I'm having a hard time understanding a 'partial' check valve

[/ QUOTE ] Then don't call them check valves and it'll make more sense. Ford calls them check valves, so we do as well, but they have nothing in common with a check valve. In short, these "valves" flow more volume in one direction than in reverse. Does that make more sense?

Bob

 

[444-4D]

[ QUOTE ]
I'm having a hard time understanding a 'partial' check valve. /ubbthreads/images/graemlins/shrug.gif

[/ QUOTE ]

It's real simple. It is a check valve but it has an itty bitty hole in the center of it.

 

[TheHammer69]

[ QUOTE ]
[ QUOTE ]
I'm having a hard time understanding a 'partial' check valve. /ubbthreads/images/graemlins/shrug.gif

[/ QUOTE ]

It's real simple. It is a check valve but it has an itty bitty hole in the center of it.

[/ QUOTE ]

LOL, It's kinda funny that most think a check valve is always 100% flow in one direction and absolutley no flow in the other direction. Yes, there are some check valves that do just that, but many applications in this world, such as reactor cooling loops, where backflow through a check valve on a non-running pump section is needed to prevent cold water accidents if that pump were to be turned on. In the case of these fuel check valves on our PSDs, the orifice is there to allow pressure to bleed off at shutdown, but the valve itself prevents the high pressure "spit shot" from feeding back through when running.

Hammer

 

[Xaviar]

[ QUOTE ]
They "suppress" the reverse flow. They do not stop it. They allow just enough to still be able to control pressure. This helps maintain steady fuel pressure in the heads from fluctuations caused by the injectors. These were only installed on "dead headed systems".

[/ QUOTE ]

Some of the regulated kits sold through sponsers here sell them both ways. With check valves removed or still in place. Since the pre 97 PSD didn't have this option would it be safe to say that later 7.3 PSD's are ok in running this way? I've been running my PSD 2000 model without the check valve/screens etc... for 2 years now. No problems at all.

Thx,
Eddy

 

[GrampyJim]

The check valves in the head have orofices in them... the only reason they are there is to prevent fuel pulsations from the opposite head affecting fuel deliver to the other head.

In a properly operating fuel system, we will see fuel pressure bleed to 0 PSI but the fuel rails will remain charged. Part of the reason for the WTS lamp on a hot engine is to allow fuel pressure to build.

 

[airfooter]

Bob,

Thank you. That explains it PERFECTLY.

So can I safely replace factory cv's with 'real' check valves if I bleed the pressure off at shut down?

-Jason

 

[NYDieselDan]

Has anyone tried T-ing off of the front fitting prior to the "bleedable" check valve and running an additional fuel line to the back of the drivers side head. At the rear port, a "zero leak" check valve could be used to help even out the flow and pulsations in the "problem" head. I don't have a regulated return but after resetting my regulator to 68 psi I checked the psi at the rear drivers side head port. The gauge flutters all over the place at various RPMS. The pulsations in this head are severe, no doubt where my cackle noise comes from in the 1500-2000 rpm range.