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Now that you have it running well, do yourself a favor and deal with the pick-up tube in the fuel tank. Like Mustang 309 said, usually its the check valve that falls out, but occasionally the thing just disintegrates.
My truck was having the same issue when I bought it. I ran out of fuel a couple of times before I figured it out; luckily I haven't had any injector failures.
I did the harpoon mod at the same time. Yeah, I don't worry about running out of fuel anymore.
I will definitely be looking into that fuel pickup issue. Going to research that a bit before I attempt it. Seems relatively easy, but I am going to want to assure I have all I need before getting at it.
They do have that screen at the bottom of the foot for a reason, though. If the intent is to get rid of the icing valve, a brass freeze plug could go in its place. While brass is not the best thing to have with diesel, the alternative is a zinc coated freeze plug which is worse.
I did a hybrid of the two options Ron discusses. Basically the second option without the black molded screen/valve assembly. Instead I formed a small bulb shape out of stainless screen and hose clamped it to the bottom of the pick-up tube, and flattened it like a pancake to get the bottom of the tube closer to the bottom of the tank. I also used stainless tubing instead of copper.
Like Ron's experience, it didn't make any noticeable difference in performance or mpg, but hasn't caused any problems either.
I was in the middle of all that and at the time had the ability to talk directly with Ford personnel, so I'll explain.
The big FUBAR that lead to all that was when Racor designed the heated fuel mixing chamber was they misdesigned the connection for the foot valve. The port off the bottom of the chamber was tapered, whereas that foot pickup, used since the mid 80's was designed to fit straight stainless tubing. So with the P131 launch customers were starting to experience fuel aeration at the 1/4 level in the tank. Around 2001 Job 2 the fix was implemented, which was to include a worm clamp on the foot to port connection. There was never a TSB or recall, so those prior would have an issue which resulted in the DIY modification, often eliminating the foot pickup.
Both the foot pickup and the mixing chamber included screens, as prior to early 2000's it was not so uncommon to get fuel with algea, which would damage the pumps. The double filtering was to prevent the pump damage and subsequent injector damage from low fuel pressure. And the mixing chamber was designed to recirculate warm fuel during gelling events. It had merit since there have been a number of instances where the chamber had to be removed due to debris clogging. And if the chambers port was designed properly in the first place, none of this would have been discussed or a mod developed around.
For the 2003 6.0 launch, the chamber went away and the heater was incorporated into the HFCM module. Unfortunately that causes wax drop out and later was eliminated from the HFCM.
The design of the foot pickup was done to address the issue of the plastic fuel tanks drooping at the bottom due to fuel weight well before the mixing chamber was thought up. It is slightly compressed on dry installation, and will extend down as the tank is filled. It has the bottom screen to prevent big materials from being drawn up, and now with the filter on the HFCM it's kind of redundant, depending on your view.
It still incorporates an icing valve. If a truck is parked for some time, historically water will separate out from diesel and remain at the bottom of the tank. Should this be during freezing weather, an ice block will form preventing draw up of fuel. That's when the icing valve opens from vacuum at about the 1/8 tank level, depending on parking grade. Actually on grade the water would be at one of the corners of the tank anyway.
Today it's not as important as it once was. Current diesel fuel is more hygroscopic so water doesn't drop out like it used to. We don't see as much algae in fuel as we used to either. The ability to stay with the bottom of the tank is still there, more so on grades. If you have a full tank having the pickup against the tanks bottom isn't so important.
It has a design purpose, but it's up to everyone to make a decision if it's needed on their truck.
When I moved my HFCM to behind the transfer case and dropped my tank, I did a half Harpoon and left the foot pickup in place. Just to state again, the 6.0 do not have the mixing chamber.
My understanding is that the design intent was to stay with the bottom as the steps on the side allows the flex. The little nibs stay against the tank and fuel pulls from between them. But I don't think it's as important as it sounds. Whatever droop that occurs when the tank is full will relax when the tank becomes low on fuel. As long as the depth is carefully transferred to the modified drop tube anyone should be fine.
If the tank stays full for long periods of time, crepe will set in and the bottom of the tank could maintain the bulged-out form when empty.
Whatever. The mods I've made are working for me, and I don't have to worry about any pieces of an outdated design getting sucked into the uptake tube and clogging my fuel lines.
After watching Ron's video I had hoped to get some noticeable improvement in fuel economy, but as with everything else I've done to this pig, NOTHING other than not driving it improves fuel economy.
It certainly seems from this thread and many others over the years that all years of diesels really need a fuel pressure sensor and alarm. No matter the type of injector, lack of fuel can cause damage to injectors or high pressure fuel pumps that will be very costly to repair. The manufacturers aren't the ones who pay those repair bills normally, but they are the ones who decide not to install an alarm at the factory that would not cost them much to implement with the PCM programming.
Larry
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