Cleaned HFCM, now losing FP

Have you checked the pickup in the tank I have seen those get a slight crack and suck air.

Already posted this....tank is bypassed

The feed line to the left is ran to that red gas can where it's drawing fuel. Supply line to the right, coming out of the pump on the pressure side, is ran to that clear jug in the background where I could watch the fuel coming out.

Although when I get this sorted out, I will end up dropping the tank to check everything out. Currently has a full tank of fuel in it, and I can't drive it until I get this issue squared away.
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Do you have a video of it with the outlet plumbed into your jug and the stock pickup being used in the tank? I just watched the video of it plumbed on both sides to tanks and then with the returns bypassed. The one with both jugs being used, air appears very slight, and is what i typically see using these pumps to pump out tanks. Granted im using pumps that were dropping pressure or a 6.4 pump that had metal go thru it, so they could be junk too. But thats not a whole hell of a lot of air. Now if it was pumping air like with the returns bypassed id be really worried.

I do not. Unless I'm thinking about it wrong here, any air should be no Bueno shouldn't it? It's sucking fuel, in a close system. The filter housing is full of fuel, the pump is sucking from that housing that is full of fuel....shouldn't be any air period I wouldn't think. Again, unless I'm thinking about this wrong.


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Im just basing it off what ive seen pumping stuff out of tanks. I dont know if its sucking air, or if it is just producing bubbles due to swirling of the fuel in the pump or something like that. Im no engineer just a guy who watches fuel get pumped nto a bucket fairly often at the dealer... As i said though, id be interested in seeing if it is an issue with the pick up or suction lines. Ive seen socks fall off and break up and plug the pck up causing weird issues. And for what its worth, i have an air dog 2 and my fuel pressure fluctuates about 3 psi on an electrical gauge. I do not have a rr yet, so that could be an issue, but mine seems to run fine. Drops to about 50 under wot.

Does the voltage at the pump stay at battery voltage with the truck running as the pump builds pressure? A bad relay can cause low voltage to the pump under load or high amp draw, It might test normal when disconnected from the pump so you would need to tee the voltmeter into the pump power supply wire and run the engine for a accurate test.
Not so sure that the bubbles in your video are a problem, It seems to pump plenty of volume of fuel. Just a idea for you.

Didn't even think to check that. Which wire is the power supply? Haven't paid much attention to the wiring...I assume they are color coded anyways. I'll try to check that tomorrow if I get a chance.


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I believe the hot wire is the pink one. The gray connector is for the pump.

I would find a hfcm that hasn't been taken apart and install it to see what it does.

Yea, that I'm considering. Through this whole ordeal, not once has it crossed my kind to take the one off my old man's 03! The little things are always the first forgotten . I'm going to run it into a jug again, pumping from the trucks tank, just to make sure it doesn't get worse, and rule out that end. If it still looks to be hfcm related, I'll pull his off later this week and give it a try before I spend the coin on one.

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6speedsd said:

Yea, that I'm considering. Through this whole ordeal, not once has it crossed my kind to take the one off my old man's 03!

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Great idea-- Im not sure how quickly these should fill/recover from a re-install, but run it for a few miles first.

The test I forgot to do yesterday because I was just frustrated at it. Only thing unhooked is pressure side to the engine, off of the hfcm. Ran a line from there to my jug. Suction side is pulling from the fuel tank. And the verdict is....

https://youtu.be/l6eqpVJotes

Well there's my problem! Was sitting there trying to decide how to go about pumping 30gal out of the tank so I could drop it, when I remembered what someone mentioned to me earlier. Sprayed a little wd40 around the suction side line quick connect with the pump running. Sucked it right inside the connector. So now, my question is this....
If I cut the thermoplastic fuel line off the steel hard line from the tank, and run a piece of fuel line from there to the hfcm, attached with good worm clamps, will it hold up permanently? Or would that just be a temporary fix? Seems like since it's on the suction side, I shouldn't have to worry about the line blowing off either end.

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ok cool, but didn't it still put some air in the output with the clamped suction hose coming from the red fuel can?

From what his video was showing with his fuel can feeding it, the air was not excessive.

As far as cutting off the end and putting a hose to the suction side, i dont know how lng it will last. I would try checking and making sure the o ring didnt roll or something stupid like that that you could easily fix.

Congrats on finding the issue.

How do you go about replacing that hose/fitting with a factory piece?

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Ive never had to replace the fitting. The hose will come as an assembly with brake lines and everything to the tank. However i was just thinking if the o ring is rolled or something, you may be able to fix it with a pocket screwdriver or a pick or something and it wont cost you anything.

did you also shoot WD around the suction tube where it goes into the hfcm case?

I did not, but I will next chance I get.

So they make you buy the whole thing...hfcm to tank. I'm sure Ford is quite proud of it too. Not buying it just yet...just getting ideas. Will check that connector/o-ring out next chance I get as well.

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Yeah i had to replace 1 in the shop. Only one i've seen. Itwas under extended warranty when i did it, and its been 3-4 years now so i dont remember the price. Hell it may not even be available anymore. You may be able to find a fuel rated o ring or something too that you could possibly install as well.

6speedsd said:

How do you go about replacing that hose/fitting with a factory piece?

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They make a kit to replace the fittings and to even repair the factory plastic lines. I have a kit with fuel line and factory ends but that doesn't do ya good. But yes you can repair it.