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2006 f350 fuel sending unit

4402 Views 57 Replies 10 Participants Last post by  TooManyToys, 
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This is my first diesel. 2006 f350 4 door long bed 4x4. I think my in tank sending unit needs to be replaced. I was surprised at the amount of options for this part. Can anyone offer some guidance or wisdom on selecting a part?
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bismic said:
It is always a good idea to change filters AND fluids immediately when buying a used vehicle. You just have no way of knowing if the previous owner took care of the truck or not. A plugged fuel filter (as an example - who knows if that is your issue) can lead to a pump failure. Pump failure can lead to EXPENSIVE injector failure. Domino effect on failures/spending.

We have already seen the poor choice in oil filter/cap - probably the previous owner. That is potentially a problem. If an OEM filter is used with a tall cap, then your lubrication oil flow and pressure is significantly reduced. This can lead to serious engine problems.

If the transmission fluid and EXTERNAL filter have had similar poor maintenance, you could be in for a big expense. Best you can do is to start good maintenance practices NOW.

Lots of videos on doing these tasks if you need the help.
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Wait........so using an OEM Motorcraft oil filter is BAD?😲
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bismic said:
Nothing "factory" inside the fuel tank except for the sending unit and pickup tube.
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And a bad sending unit could make a LOUD humming sound?

See I'm lost on this one. Airdog pump is actually fairly quiet now with new filter and separator drained, but SUPER loud noise coming from tank still and truck has one of those fuel return line set-ups so not sure what that entails to be honest.

Fuel tank looks stock and free of modifications so don't think it has a sump or anything like that and I'm very curious why a sending unit in fuel tank is still necessary when truck has a lift pump running? Isn't the lift pump enough on it's own?

Seriously any feedback here would be greatly appreciated :)
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wpg_f250 said:
Wait........so using an OEM Motorcraft oil filter is BAD?😲
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No, but you need to use an OEM oil filter cap along with the OEM oil filter.

Some people INSIST that the aftermarket oil filters with the integral cap will work as well as OEM. People have shown otherwise - that they are not as reliable (mechanically) and can come apart and create debris that might get into the oil system.

There is a message on these integral caps that states "DO NOT REUSE", but people do it anyway. When they throw in an OEM oil filter into an aftermarket cap, then it is the WORST of both worlds.

Please do not construe that OEM filters are bad .....................................

Also - a bad sending unit isn't going to make any noises (IMO anyway)!

Just a request though - I think all this should be in your other thread, not mixed in with @Codyvollmers issues/needs.

EDIT (and last post here):
The sending unit is for tank level ...............

The HFCM, which is on the frame rail, is the ONLY fuel pump that is needed from the factory.

An added Air Dog pump may or may not need what you are calling a lift pump - most don't, but only you can determine what you have.
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bismic said:
No, but you need to use an OEM oil filter cap along with the OEM filter.

Some people INSIST that the aftermarket oil filters with the integral cap will work as well as OEM. People have shown that they are not as reliable (mechanically) and can come apart and create debris that might get into the oil system.

There is a message on these integral caps that states "DO NOT REUSE", but people do. When they throw in an OEM oil filter, it is the WORST of both worlds.

Please do not construe that OEM filters are bad .....................................

Also - a bad sending unit isn't going to make any noises (IMO anyway)!

Just a request though - I think all this should be in your other thread, not mixed in with @Codyvollmers issues/needs.
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Ahhhh ok lol. My cap is stock and new filter is OEM so PHEW😁

TY
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jokester00
Wonder if you're sucking air from something inside the tank. Possibly a damaged tank pickup foot. Do you hear the loud noise only when the pump is running or does it continue once the pump shuts off?

-jokester
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jokester00 said:
Wonder if you're sucking air from something inside the tank. Possibly a damaged tank pickup foot. Do you hear the loud noise only when the pump is running or does it continue once the pump shuts off?

-jokester
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Don't think I'm picking up air as the truck runs great and has zero loss of power and noise is so loud I thought it was the lift pump, but when I was under it changing the fuel filter I was surprised to find it was actually coming from around the front of the tank.

And noise starts when key on/engine off and just get substantially louder when key on/engine on and when the ignition turns off noise stops a second later. It 100% sounds like mechanical humming from a motor of some kind so got me lol.

I'll post up a vid here soon.
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jokester00
wpg_f250 said:
Don't think I'm picking up air as the truck runs great and has zero loss of power and noise is so loud I thought it was the lift pump, but when I was under it changing the fuel filter I was surprised to find it was actually coming from around the front of the tank.

And noise starts when key on/engine off and just get substantially louder when key on/engine on and when the ignition turns off noise stops a second later. It 100% sounds like mechanical humming from a motor of some kind so got me lol.

I'll post up a vid here soon.
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Maybe you have a lift pump inside the tank that feeds your AirDog pump (redundant system)? Do they have a system like that?

-jokester
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H
With mods, ...who knows what has been done
only way is to drop the tank and look
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jokester00 said:
Maybe you have a lift pump inside the tank that feeds your AirDog pump (redundant system)? Do they have a system like that?

-jokester
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Hydro said:
With mods, ...who knows what has been done
only way is to drop the tank and look
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Yeah I'm not sure what the previous owner did so first I'll check to see if there's any power going to the tank and if so I guess I could just try to backtrack that power line and then remove line from power system and see if that stops the noise, but yeah probably have to drop the tank.
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TooManyToys said:
I was hoping you had an image of the chamber's themselves. Were the ports clear?
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everything seems clear and clean. So now you recommend running fuel from a temp tank through the pump and seeing if it runs?Rhat would show that the pickup line from the tank is blocked?
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TooManyToys
Considering the video I'm working on right now, that HFCM is spotless. I'm guessing you checked the cover ports, too.

I had to re-read this thread as I'm responding to too many things, and this thread feels like it's becoming a "who's on first" ... joke. Having sinusitis isn't helping.

My re-cap: You had problems when the tank was 1/4 full. It was the de-icing valve that popped out of the foot, but the foot or valve did not break into little pieces that could clog the line. In fact, you blew out the line to make sure it was not clogged.

Now, you can't pump fuel at all, although the pump does run.

So....

It's possible the connector at the top of the tank was not fully locked, and you might be drawing air. Or the connector at the intake port of the HFCM. So I would do the hose to the intake port on the HFCM to a can of diesel and see if that works. Just trying to do this one step at a time.

Some people say they had issues priming the pump. That should not be an issue, but if it is, pouring a quart or maybe enough diesel to half-fill the secondary filter canister should take care of that.

Assuming this HFCM also has a filter in place and the cap o-ring is good.
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TooManyToys said:
I was hoping you had an image of the chamber's themselves. Were the ports clear?
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everything looks good and clean. I put it all back together. Still not getting fuel to the bowl. I was thinking I should replace the electric fuel pump module in the Hfcm? I feel like that’s the next step? What do you think?
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TooManyToys said:
I was hoping you had an image of the chamber's themselves. Were the ports clear?
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If I power cycle the truck I hear the Hfcm run for 10 sec or so but I don’t get any fuel in the bowl. Does this mean the electric pump inside the Hfcm is bad even though I hear it running? Or is it something in between the Hfcm and the bowl?
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TooManyToys
While your thread has been progressing, I was finishing up with a video that I had put off for some time. It covers two people with similar issues of running but not pumping HFCM. When they sent them to me, the agreement was to do full forensics, which included disassembling the pump. Those issues were years back, and at that time, everyone was looking at those situations and a bad electric pump. Neither were. One was debris in the HFCM cover, and the other was debris in the nipples of the HFCM. That is extremely rare. But the one with the debris in the ports also showed the internal relief valve was tripping. These pumps make a loud, unusual noise when that happens. My own truck did that when I had a line blockage.

I'll add the video as it has a list of things to go through. But if the pump is running and it has good voltage, there has to be either a supply or delivery issue.

The list from the video.

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To me, I wasted at least one good pump because of the 'forensics' approach, but that was the intent of all three of us to waste these to help others. Dave went through another new HFCM, and that may have been due to him not seeing the debris in the nipples/ports and my not looking as quickly as I should have.

An absolute test of the HFCM, if the o-rings are good, is to remove all hoses, loop the top nipples with 5/16" hose, and run 3/8" hose from the bottom nipples into a can of diesel and see if it flows. If it does, reconnect only the in-feed tank line and see if the supply circuit is good. If it's clear, you'll be pumping fuel from the tank into your diesel can.

The video with a guest voice.

Two "Failed To Pump" HFCMs.
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Excellent vidro, Jack
thorough as usual and informative

Salt water in the fuel would add to the corrosion

The blocked ports should have been found if the owners would have ran a trimmer string thru the ports and lines, when there is a question of flow
this has been suggested many times on the forums, ...but how many times actually done
and easy enough to check pump flow on the truck with a remote tank and clear hoses

...but I am not saying anything several here don't already know
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TooManyToys
In Dave's postings, he quickly mentioned a filter issue early on but never posted much about it, nor any images. In the images of others who had received bad fuel from a station, the interior of the HFCM filter cavity was contaminated, but when they pulled the pump, the clean side was also. So these primary filters can collapse and allow contaminates to get pumped throughout. Pretty strong little pump.

With Robert's HFCM, as soon as I opened the cover, I knew the problem was most likely only in the heater chamber, but no idea if the pump had issues, so I took apart the pump. With Dave's, I missed the ports because when opening the cover, it had been cleared. But I did not initially look at the ports. In all the threads I've read or participated in, I think there was only one that had a comment to check the ports, and if I'm not mistaken, it was your comment, Hydro. I was going to paste that into the video, but I couldn't find the thread or just missed it.

Anyway, that pump I was happy that I took it apart because of the evidence of the relief valve bypassing dirty fuel.

I could have made it into a 5-minute video (gave an out with the spoilers), but I thought some might enjoy the journey.
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Great vid, Jack
I am one that does enjoy the journey -- and solving puzzles
The pump with the crud in the return ports is a bit of a mystery -- would have been interesting to see the rest of the truck on that one
To get crud in that line would mean that the return from the upper filter could have crud all the way to the filter housing
I would have expected the flow thru the system to keep the line flushed out

Maybe I have advocated to run a trimmer string thru the ports so many times that I thought is would be common practice by now -- or that just rattles around in my head
Hard to say how many times guys at the shop have said they blew the lines out and can hear air in the tank
only to find out later that there was still blockage in a fitting or bend in a line
so, I got used to telling them to "run a trimmer string thru and prove that the line is open"
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TooManyToys
Most of my content and the tale of these two HFCMs were over on FTE. Talking about the supply line blockage and clearing has been discussed enough that I didn't bring it into this video since I had it in the fuel tank video. But it's the inspection of these ports that I think hasn't been discussed that often. This was the unusual case where he could have trimmer lined the supply line, and it was clear - but he just never checked the ports. Same with Robert's, check under the cover. What I was hoping to point out was the cover has to be removed, and the ports checked, especially if there is a heater.

After seeing Dave's ports, I agree it would have been interesting to see the rest of the fuel system. I did a brief mention about his first replacement HFCM failing, and I didn't want to harp on it too much, but my gut is thinking one or more of the ports had to re-clog since the new HFCM worked, and connections at the engine, tank, had to have debris that got loose and moved. He didn't clean the tank or any of the lines, from what I could tell. It was an "HFCM failure", so change the HFCM. Much cheaper to spend more time diagnosing the problem.

Hopefully, it helps someone.
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