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I have read several posts about this topic but have not seen any that were solved. If there is a thread to a resolved issue like this, it would be great if someone directed me to the post. So I am posting my issue to seek help. 2016 - 6.7 with 21,000 mi. Changed frame mounted fuel filter, o ring, canister, water sensor and drain plug and under hood filter as well. All OEM parts. Filled canister with diesel, tightened to the stop. Did not over muscle the canister. Cycled key 10 times.
Will not start. I can hear the pump running each time.

So, I removed the discharge side of the secondary filter and connected a clear tube. Not getting fuel out of the upper filter only air. Where else can the frame mounted pump suck air from? Repeated the process at least a dozen times looking for what i messed up, still no clue same results. HELP
 

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Did this concern begin after replacing the filters or did you replace all that trying to fix it?
 

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Discussion Starter #3
Did this concern begin after replacing the filters or did you replace all that trying to fix it?
Just doing a routine service at 21000 miles. Oil/filter change, air filter change and the fuel filters. I have checked all work/parts at least a half a dozen times. I am at a loss. O ring is lightly lubed, new drain with new o rings tightened, new water sensor with new o rings tightened. Tightened the cap very carefully so I didn't crack it like a lot of advise I have read. Cap is at the stop. My first attempt was to use the original cap, drain plug and sensor and new filter and o ring (OEM parts). Pump would not prime. Replaced everything with new in an attempt to resolve the issue, that maybe the cap was cracked. So, with all that, where is the air coming from is what I keep coming back to...

I have a bleed hose in a jug from the 'out' side of the secondary filter and when I cycle the key I get a steady stream of bubbles while the pump runs the 30 seconds or so.
 

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Discussion Starter #4
Just doing a routine service at 21000 miles. Oil/filter change, air filter change and the fuel filters. I have checked all work/parts at least a half a dozen times. I am at a loss. O ring is lightly lubed, new drain with new o rings tightened, new water sensor with new o rings tightened. Tightened the cap very carefully so I didn't crack it like a lot of advise I have read. Cap is at the stop. My first attempt was to use the original cap, drain plug and sensor and new filter and o ring (OEM parts). Pump would not prime. Replaced everything with new in an attempt to resolve the issue, that maybe the cap was cracked. So, with all that, where is the air coming from is what I keep coming back to...

I have a bleed hose in a jug from the 'out' side of the secondary filter and when I cycle the key I get a steady stream of bubbles while the pump runs the 30 seconds or so.
I should mention that this is a 2016, 6.7 F550 in a Motorhome configuration. Two tanks, both full. I am drawing from the closest tank to the pump.
 

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Remove the canister and check that the mating surfaces are clean. Try switching tanks. Can you hear the frame fuel pump? Look at the wires going to the pump. Make sure nothing is lose.
 

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Yes, i have checked the wires, the pump seems to run fine, just no suction of fuel, only air. If i fill the filter canister with fuel, it pumps it out of the 'out' port on the upper filter, then stops when the fuel is gone from the canister. I have used both tanks just to ensure it is not a tank problem. To be clear, this was only supposed to be a routine service, there were no issues when i started. Just a simple filter replacement effort.
 

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lazyboyrider, I ran into a similar issue when I did my Hutch Mod on my ‘02 F350, adding a pre pump filter on the frame rail. I just happened to notice a tiny, tiny drip down the side of the Baldwin filter where it wasn’t seated completely. It doesn’t take much at all to suck in air and still not leak diesel fuel on the ground.
Sounds like you need to disassemble- reassemble the fuel filter canister again, checking your gaskets/seals, hoses, and hose connections again, I’m sure you’ll catch it when you go back over everything again.
 

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I have removed and reinstalled the fuel filter canister so many times now, i can do it blindfolded. 10 times at least. VERY careful but same results. Is it possible to have a crack the fuel pump body? Or is there a check valve someplace that could be stuck closed? This is such a simple thing to change out, and that is what is driving me crazy. It should not be this problematic.
 

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Since it was fine before you changed the fuel filter, and now is not fine after you did nothing but change the fuel filter, my first suspicion would be that it might have something to do with changing the fuel filter. Since you have already removed and reinstalled the fuel filter 10 times, and it is still leaking after every time, why not try another fuel filter. Is it possible that the new fuel filter that you bought is defective, or is it possible that it is not the compatible fuel filter?
 

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Discussion Starter #10
As I have posted, I have changed everything related to the frame mounted filter except the pump and it runs and had no issues before. Canister, O ring, drain plug, water sensor, filter - all new OEM parts. I really dont like 'chasing the repair by part replacement' but that is where i am. Complete pump assembly will be next if i dont stumble on what is wrong.
 

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Even OEM filters could be wrong or not work correct. Personally I would just get another filter and see if you get a different result. I know it's more money but you can always use another filter. I would compare both filters carefully to make sure everything matches correctly. i would also get them at the dealer and not online if that's where you got them from. You need to bring your vin just in case.
 

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ok i havent changed the ones on my 2016 yet, just got it, but i had issue with this on my 6.0 so forgive me if the fuel filter on the frame of the 2016 is totally different. The 6.0 filter had to go into a specific slot/place or when you tightened it up it would not pump fuel - i think it opens/releases some valve or something in the housing, like a bypass if filter clogs?

16 might not be like that but i did tighten mine down that way a couple times over the years and thot i had it in the right way. I also broke something on one of the filters that wouldnt press down properly and release/press on whatever it did in there so maybe the 16 could be like that. Do the filters look any different physically? Maybe the oring is cut/bad? It doesnt take much.

forgive me if i am off base just throwing things out there to try to help
 

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2016 DFCM filter (lower filter) is different than the 6.0L lower filters. The lower element seems to snap into the DFCM housing. It might be possible the filter isn't seated correctly but sound like he's done it more than once covering just about every aspect I'd suggest to check. Best of luck!
 

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Discussion Starter #14
Finally got this fixed. But never resolved how air was getting into the system. Replaced the entire pump unit with new ($300) and it primed like it should. Purged the air with the 6 time key, 30 second routine and engine fired up like normal. Issue solved but a routine replacement of the fuel filter should not be like that. Thanks to those that offered help, unfortunately, the only remedy was to replace the entire pump.
 

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Never know...the housing could have been cracked. Good to know it's back running right.
 
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