Air intrusian question????

[dyoungen]

Does anybody know if there is a one way valve made for our trucks fuel system to stop air intrusion? It seems to me it would be a good idea to be able to stop the fuel from draining back to the fuel tank.

 

[BDCarrillo]

Some folks have used one on the return run back to the tank. I have one between the filter head and lift pump. A 1 psi cracking pressure ought to be fine.

 

[OLDBULL8]

Just fix the fuel leak/air intrusion.

You could try drain back with two electrically operated solenoids. The lift pump side would have to have an 3/8" orfice, the drain back side would have to have an 5'16" orfice. Those solenoids are pretty expensive.

 

[franklin2]

I believe there are already factory check valves in the incoming fuel lines correct? The return line running down the backbone of the engine is the problem though. I thought about the solenoid valve solution myself.

Here's one for $55.00.

http://www.surpluscenter.com/Hydrau...FORCE-12-VDC-N-C-SOLENOID-VALVE-9-5112-NC.axd

 

[dyoungen]

I was thinking something like a water line one way valve. I can't find any wet spots but it seems I"m looseing my prime somewhere. REplaced the return lines, all of them including the clamps. I'm wondering if these clamps might be a problem. I could understand if the hose was old and hard but the hose is plyable.

 

[BDCarrillo]

No factory check valve on the supply side. The pump should act as one.

I'm all for fixing the issue, but I've been in the same boat as the OP where a check valve was the only thing that worked. I pressurized and applied a vacuum to the supply and return side of things, even pumped up the tanks with air. New tygon return lines, new o rings, new rubber lines to pump, new one piece filter, plugged heater connector, etc etc. Sometimes the intrusion source is damn near impossible to locate... in those cases a check valve or electric pump should be acceptable fixes.

Fuel rated check valves can be found online. I'd be worried about the material in one meant for water.

 

[IDIoit]

seems like an expensive way to fix a problem.
most of the time its a busted nylon line, in this case, it cost about 6 dollars to fix, with the right adapter.
even cheaper to replace every rubber line with hose clamps on your rig.
lift pump, o-rings, olives, if any of these are leaking, i dont think this solution will help any.
JM2CW

has anyone ever disconnected the lines and ran a smoke tester through them to find leaks?

 

[BDCarrillo]

I didn't use a smoke tester, but pressurized them with just air and checked every imaginable spot with a soap/water mix.

 

[IDIoit]

every leak ive had, minus my GD WFS was very visable.
nothing say "leaking" like a nice puddle of diesel on the frame rail.

 

[dyoungen]

I have an electric pump under the cab but still I'm looseing the fuel and can only guess it's going back to the tank. None leaking onto the floor and the fittings all seem dry. I like Franklins link. If I can't figure out something pretty soon I'm tempted to get those selnoids.

 

[OLDBULL8]

Just ran into what your looking for in check valves, you have to scroll down to see the different sizes, there across the bottom of the page. I don't mean the Navistar one. There is both 3/8" and 5/16"

http://www.ebay.com/itm/1813248C1-C...Parts_Accessories&vxp=mtr&hash=item2ecfded1b2

E$ven better price

http://www.ebay.com/itm/10mm-3-8-Fu...420&rk=4&rkt=6&mehot=ag&sd=201055982002&rt=nc

 

[franklin2]

Just ran into what your looking for in check valves, you have to scroll down to see the different sizes, there across the bottom of the page. I don't mean the Navistar one. There is both 3/8" and 5/16"

http://www.ebay.com/itm/1813248C1-C...Parts_Accessories&vxp=mtr&hash=item2ecfded1b2

E$ven better price

http://www.ebay.com/itm/10mm-3-8-Fu...420&rk=4&rkt=6&mehot=ag&sd=201055982002&rt=nc

I can't see where they say if it has a spring in it and what pressure the spring puts on the check ball or whatever is in there.

You really can't put a "check valve" in the return line and expect it to work properly as it was designed. You want the fuel to flow back to the tank when the engine is running, but you don't want it to flow when the engine is stopped. There is really no way to do this in the return line unless you do what the other poster mentioned, and had a check valve that had a spring pushing the check closed, and the spring was weak enough to be overcome when the engine was running, and strong enough to hold the fuel at the engine when the engine is off.

 

[franklin2]

Another question I have is about the injection pump and what role it plays in the air getting in. When the air is let into the system, am I right in saying fuel leaves the IP as well as the return lines? I also get the impression the injection pump actually stores a little bit of fuel inside it?

What I am leading up to, is if we had a solenoid that was hooked to a fitting on the injection pump, and this solenoid opened when the glowplugs were active, along with a electric fuel pump we could quickly prime the fuel filter and the injection pump, and get it ready to start. I am thinking the electric fuel pumps help, but do not totally get rid of the problem because the IP has lost fuel and is now airlocked. The electric fuel pump can't fill the injection pump if the air can't be bled out of it.

Is there a way to help the air get out of the injection pump when the fuel leaks out of the system? That would be the way to go. We could just let the system leak as long as we can fully prime it before we try to start the engine.

 

[TahoeTom]

Have you replaced the olives yet? I had air intrusion with no visible leaks. I replaced the olives in the line from filter to IP and the problem went away. There is an olive at the filter inlet, and on 6.9 IPs one where the return line comes out of the top of the IP, and another at the copper "T" where the return lines come together at the rear of the engine.

 

[BDCarrillo]

I can't see where they say if it has a spring in it and what pressure the spring puts on the check ball or whatever is in there.

You really can't put a "check valve" in the return line and expect it to work properly as it was designed. You want the fuel to flow back to the tank when the engine is running, but you don't want it to flow when the engine is stopped. There is really no way to do this in the return line unless you do what the other poster mentioned, and had a check valve that had a spring pushing the check closed, and the spring was weak enough to be overcome when the engine was running, and strong enough to hold the fuel at the engine when the engine is off.

A spring loaded check with a .33 or 1 psi pop pressure would work properly while running and stopped. It's what I use on my truck.