Fuel filter housing question

[Ryland]

I was changing my fuel injectors/IP and installed all new return lines, gaskets and what not and when I got to the circled hose there was still pressure on it when I took the hose off and it sprayed all the way across the engine bay from what I understand that is a check valve the hose is attached too and it recircs some fuel back to the tank.

When I inspected the hose it is plugged off right where it attaches to the barbed fitting so I’m assuming somebody plugged it at some point.

So I just wanted to check and make sure that I am able to throw that hose out and just put a regular hose on it.

Thanks in advance! I attached an image to this post and hopefully it works

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[gandalf]

Yes, I'd definitely replace that hose with one which is not plugged. It's part of the return system, and therefore serves a purpose.

 

[Ryland]

Okay thanks, it looks like someone literally shoved something in the hose and then put it back on, I found some posts regarding plugging it off so it seems like it’s kind of a common thing to do but it seems like it just covers up other problems and doesn’t actually fix the issue

 

[chillman88]

To each his own. I plugged mine years ago (there was actually a service bulletin from Ford that said to plug it). I haven't had any issues, even when I've run it out of fuel.

 

[Ryland]

Hmm very interesting

 

[IH-GM IDI]

What dues the TSB state the purpose of blocking the return line is?

 

[chillman88]

What dues the TSB state the purpose of blocking the return line is?

I haven't been able to pull it up to verify, as I no longer have my alldata account, but the purpose is to prevent hard starting as a result of fuel drain back from a failed check valve.

 

[Selahdoor]

I haven't been able to pull it up to verify, as I no longer have my alldata account, but the purpose is to prevent hard starting as a result of fuel drain back from a failed check valve.

And it sounds like it was worse than a bad check valve, on the OP's housing.

When he pulled it off, it shot fuel across the engine bay. That's pressure where there should be none at all. The hose was plugged, so the fuel didn't shoot out of the hose.

Near as I can tell, that system was designed to relieve excess pressure in the return lines, should the return line that leads back to the tanks become partially plugged.

The check valve was supposed to let fuel into the filter head, not out of it.

If it lets fuel out of the filter head, the system will drain down overnight.

Exactly the same as if the check system in the fuel pump feed was not working correctly, and allowed fuel to flow away from the fuel filter head overnight.

 

[IDIoit]

I delete that line completely.
the 6.9's had that hose nipple on the ip feed line fitting.
I either plug that return nipple on the caps with a bolt, or swap to a single nipple cap for #1

 

[Macrobb]

And it sounds like it was worse than a bad check valve, on the OP's housing.

When he pulled it off, it shot fuel across the engine bay. That's pressure where there should be none at all. The hose was plugged, so the fuel didn't shoot out of the hose.

Near as I can tell, that system was designed to relieve excess pressure in the return lines, should the return line that leads back to the tanks become partially plugged.

The check valve was supposed to let fuel into the filter head, not out of it.

If it lets fuel out of the filter head, the system will drain down overnight.

Exactly the same as if the check system in the fuel pump feed was not working correctly, and allowed fuel to flow away from the fuel filter head overnight.

Pretty sure this is not the case. It's intended to let air out of the top of the filter head, for priming(and air bubbles mixed into the fuel) - that's why it's a small orifice - you don't want to lose all your fuel pressure.
The check valve prevents air going back into the filter.

If it were intended to allow for return fuel back into the filter head... it wouldn't work at all. The orifice size is too small; it couldn't pass enough return fuel for the pump to have any noticable difference either way. Plus, the pressure in the return side would be higher than the supply side for it to do anything, and I don't think the pump would continue running under that condition anyway.

 

[chillman88]

The check valve was supposed to let fuel into the filter head, not out of it.

If it lets fuel out of the filter head, the system will drain down overnight.

As Macrobb said, the check valve was designed to let air out, and into the return lines. The purpose of the check valve was to stop fuel from draining! It's at the high point in the fuel system, exactly where any air would collect. When the check valve is working properly vacuum keeps the fuel filter full, as the fuel can't fight the vacuum to drain back. When the check valve STOPS working, it lets air back in from the return line system, and the fuel will drain back through the pump to the tank.

 

[Macrobb]

When the check valve STOPS working, it lets air back in from the return line system, and the fuel will drain back through the pump to the tank.

To make things more murky, this also only happens when the check valves in the lift pump stop working perfectly - otherwise, well, the fuel can't drain back as it has nowhere to go.
So, if either of these two factors work right(or you have an added check valve in the supply line somewhere), you won't have the drainback issue(related to this).

 

[chillman88]

To make things more murky, this also only happens when the check valves in the lift pump stop working perfectly - otherwise, well, the fuel can't drain back as it has nowhere to go.
So, if either of these two factors work right(or you have an added check valve in the supply line somewhere), you won't have the drainback issue(related to this).

Is fuel able to drain through the IP return at all? Assuming air coming through the filter return orifice, would fuel drain through the IP or is that closed off completely via the FSS when the truck is off?

 

[Thewespaul]

The pump has a pressure relief valve built into the lower fitting on the return outlet. Pressure has to meet a certain amount for the valve to open and fuel to flow through and unless the pump is rotating this pressure won’t be met so there’s no way for fuel to drain back through the pump return.

 

[Selahdoor]

Wes, that is correct. No matter what it is called, the flow is "checked' at the pump. Unless the pump is compromised somehow.

The rest of it. So you guys are saying that the ball goes into the filter head first, then the spring, then the fitting?

Because mine came out the opposite. Spring was in the head, first, then the ball, then the fitting. Pushing the ball against the fitting. Not against the head. This would keep anything from the head, from entering the line. But pressure from the line would make it's way in to the filter head.

And that makes sense to me. That would keep the filter head from bleeding down, through the return lines, overnight. Or from simply dumping the fuel out of the fliter head, through the return lines, when everything is in operation.

Seriously guys, think about it. The fuel pump is putting pressure on the fuel filter. If the check valve was set in there the way you say it is, fuel would be pushed out that line all the time, when the pump was running. Just push in on that schraeder valve, to see what kind of pressure is there. That tiny spring in this check valve would not hold back that kind of pressure. It would constantly be pushing fuel through the return lines. And with the slightest leak anywhere in the filter or head, it would be draining the fuel out of the filter and head, down the return lines, over night.

Regardless, I have taken the advice of Wes, and Macrobb and others here. I removed that line. Removed the fitting and ball and spring. And put a plug in it's place. Also like Macrobb, I re-routed that line, over to the top of the IP, and teed it in with the line that goes to the return lines.

I have experienced zero problems with this. (Didn't have any problems with the check valve still there, either. That I can recall. Just decided it made sense to take care of it before there was a problem.)