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Discussion Starter #1
I had a sump installed on my fuel tank. The old fuel line with the blue plastic tab on it was capped since the tank was not removed for the sump installation. I ran 2 tanks of fuel through it and just topped it off for the third time. I drove about 10 highway miles, stopped for 20 min and found a big puddle of fuel when I returned to the truck. Drove it home while it was leaking, put a clamp on the line to stop the flow of fuel. The guy who installed the sump came over and put a different cap on the line and it stopped leaking. Went to drive it to work next morning, got about a mile from the house and truck sputtered and quit while driving. Got it home and pulled the fuel filter cap off and found no fuel in the filter housing. Turned the key and fuel pump pumped the bowl full, as soon as the key was turned off, the fuel started draining down to empty the bowl. But it didn’t go on the ground. Not sure where it’s going but it won’t keep the fuel in the filter housing.
 

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It's running back into the tank, likely via the return line.
I thought the upper filter was supposed to have a check valve to help prevent that.

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The check valve is located at the engine head, after both filters. There is an additional check valve located in the HFCM. The Check valves are the circles with the triangles.

I think whatever leak you saw is letting the fuel drain back into the tank. If you can find and fix that leak, I believe your problems will go away. My guess is the leak would be in the sump pump, since the work was done there, but it could be anywhere. I also am not sure the lines need to be primed with fuel to allow the pump to work.
 

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In 2004 there was a goose-neck (or trap) installed in the fuel feed tubing to the regulator on the secondary fuel filter. It was installed so that the secondary fuel bowl would not drain down.

Do you have an 03 or early 04 engine?
 
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Discussion Starter #5 (Edited)
The fuel pump is getting fuel to the secondary filter bowl and it will overflow all over the place if I leave the key on with the cap off. As soon as I turn the key off, the fuel drains out of the bowl followed by a weak hissing sound like it’s sucking air after all the fuel is out of the bowl.
My truck is a 2006.
 

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There is a duckbill type valve on the fuel return line to the tank. I wonder if it is allowing air to leak back.

I thought it was fairly low in the tank (submerged) though.
 

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I would think you would need to have a leak up top where air is getting in, for it to drain back.
Think of the straw effect.
Regardless, not too terribly hard to pull the sender and look.

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are you having issues or just noticed the fuel bowl draining ?

did the old fuel tank supply line get capped so low outside the tank that it was causing a siphon effect?

have you tried this test with the fuel filler cap off ?

and in case you have not noticed the fuel pump shuts off on it's own after key on but no start ( not that this effects you but just fyi )
 

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Discussion Starter #9
are you having issues or just noticed the fuel bowl draining ?

did the old fuel tank supply line get capped so low outside the tank that it was causing a siphon effect?

have you tried this test with the fuel filler cap off ?

and in case you have not noticed the fuel pump shuts off on it's own after key on but no start ( not that this effects you but just fyi )
The truck won’t run is the issue.

The old line is capped off just above the water separator fuel filter

Yes- that’s how I know the fuel is draining out to the point the bowl is empty. If I leave the key on with the cap off, it will pump fuel to fill the bowl and then it overflows and continues until the key is turned off

Yes I did notice the pump shuts off however that’s not the case when the cap is off. Maybe it’s because it doesn’t build any pressure with the cap off.
 

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The truck won’t run is the issue.

The old line is capped off just above the water separator fuel filter

Yes- that’s how I know the fuel is draining out to the point the bowl is empty. If I leave the key on with the cap off, it will pump fuel to fill the bowl and then it overflows and continues until the key is turned off

Yes I did notice the pump shuts off however that’s not the case when the cap is off. Maybe it’s because it doesn’t build any pressure with the cap off.
I noticed my 07 fuel bowl was empty when I changed filter, with longer crank times after sitting. I just bought the truck and was working through the to do list. I installed the blue spring kit and noticed the rubber seal on plunger was deformed looked original. No more long crank times for me, haven't pulled fuel filter though.
 

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Also have a 07 and when I started to remove the filter car off could hear air rushing in and the fuel draining and was empty when cap was removed and thought the same should have fuel there so do I have a problem as well? Have not tried to start as I also did a glow plug change on driver side and just got this done the fun just never ends. So should this filter drain and do mean the one under the hood?
 

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Something is not right. I can only recommend tracing the fuel lines back for obvious leaks. or kinks. There's supposed to be a check valve inside the fuel pump area that prevents the bowl from emptying. I would not spend $500 to switch the HFCM without further troubleshooting though.
 

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That is what I thought and no leaks in lines and truck ran very well before I did filter change. So next is just were is this check for sure so I can check it out?
 

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On post #3, there's a block diagram of the fuel system. These check valves are the circles with three triangles on them. They are located inside the HFCM (fuel pump housing). This check valve sits at a low point in the fuel system preventing the fuel above it from draining back into the tank, kind of like a finger over a hose when siphoning fuel.

I've been told by one of my previous mechanic that unit is non-serviceable and needs to be replaced as one unit. Short of buying a new one, or swapping a spare, I'm not sure how to check it. That is a lot of cash and effort if my educated guess is wrong.

In my signature block is 6.0 good reading, otherwise known as the 6.0 bible. That's the best document I've found about the overall engine in out trucks. There's a section on the fuel system to read up on.
 

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Two places that fuel can leak back to the tank, the first is the check valve on the fuel pump outlet(in the HFCM), the other is the fuel pressure regulator in the secondary filter housing(there is an air vent, but it will only partially empty the bowl). Either the valves are damaged or they have junk in them.
 

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I will get back to this after I fix my explorer this weekend and will see if I can get it running but did drain all fuel out of canister and was full or or mostly full as it did take time to get cap off and did hear draining a long period of time. Truck always started up well not a lot of cranking so am guessing it had fuel in canister even with 2 bad glow plugs and that is from codes I got. Also were is the egr valve is that on front top of intake? Hope I do not have to replace the pump as I did try to get lines off to reseal the drain cap as this one looks to have weeped but not drips on floor and have kit for it and wanted to do when I replaced filter but that did not happen. If I had the drain plug out at the time I took off upper cap would that do it? Have to finish this and look at diagram again to see.
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Look on page 18/13, bottom pic, item 3 of the document in my signature block, 6.0 good reading. The EGR valve is at the front of the intake, behind the intake elbow, where it forms a U, is black on the top, and is held by two bolts. If its been deleted, there may be some sort of cap there.
 

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In looking at diagram again it could be going through the fuel regulator valve as in drawing it looks to be out of the bottom if drawn correctly this be correct? I looked and the fuel filter housing is were the regulator is is this were the blue spring update goes? Do not want to play to much and get into more problems or spend money fixing things that do not have to be done. But should get running again and check pressure of system and is the 60 psi number correct for a stock setup? Also how low is to low? Have seen were the egr is and that is what I though have to pull that to see if wet as am loosing coolant as well but no white smoke when I had running so not sure just were it is going so checking all spots but nothing leaking on floor. Have to many projects and after work sometimes hard to go out to garage to work and not as young as I once was but will get it done sometime.
 

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The blue spring mod is in the front of the upper fuel bowl. The line towards the front is the fuel return line. Somehow the blue spring sets the 60 PSI by opening the spring to let it flow back to the fuel tank. Although it says the range should be 55-65 PSI, as long as pressure stays above 45 PSI at all times including wide open throttle, the injectors are not being starved of fuel. Mine will dip to 52 PSI at WOT, and is usually around 58 PSI.

As far as not opening up the fuel regulator, it can be wise. If you lose one O-Ring when you open it, Ford does not sell the O-Rings individually, but as a set either Blue Spring or Fuel Bowl Rebuild. I found out when I lost an O-Ring during the Blue Spring rebuild and could not find a replacement O-Ring, and purchased the kit. Not many stores have a set of O-Rings lying around to match shapes. I'm told some NAPA stores do.

As I read the air bleed in the diagram, it is separate than the fuel regulator. I don't know how that second valve Hydro mentioned works in the upper fuel bowl to get the air out. I see the air goes to the return line to the tank, but don't see how it is it keeps from draining back.

I seem to remember someone posting the Blue Spring kit was installed incorrectly and never seated shut, and fuel was draining out of there through the return line to the tank. Unfortunately, I the Blue Spring kit is about $75 and would be expensive to test that.
 

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Well in reading these answers I am thinking this all air is out of canister and holds fuel with check when I broke seal and air could get in it drained not correct but this is my thought. Have a 95 7.3 and you had to take fuel out or insert filter slowly or use drain so you did not have fuel all over. So I do know that it should hold furl and this was until breaking the seal. So will have it running this 4 day weekend as I will bring in explorer saturday morning after I go to breakfast to dry out if needed like last weekend we had snow. So will hook up exhaust fan and see what happens as it tends to stink up the garage badly. OH can you get egr valve out without the puller tool? Will it come out with twisting it and pulling by hand? Or do I need to find one to rent?
 
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