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Discussion Starter #1
Hello,
We have a 2009 F350 with a 6.4 that keeps cracking the secondary/ engine mounted fuel filter cap. I’ve tried bleeding air from the system and it’s still swelling the cap. When turning the key to activate the fuel pump I can see the cap lift or swelling before starting the engine then it eventually cracks near the hex on top after doing about 30 miles. Any help or ideas would be appreciated. There doesn’t seem to be much out there on the 6.4. The truck runs great and has no check engine codes.
 

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The horozontal fuel conditioning module , HFCM, is the fuel filter housing under truck and has the electric fuel pump and also has the low pressure fuel system pressure regulator. Since the cap swells when key is switched to run position w/0 engine run, the pressure regulator there must have a problem is letting the pressure go way too high. The pressure should be about 25 psi. I have not had an HFCM on a 6.4 give me any problems so I have not investigated that regulator and the only illustratiions of the HFCM show lots of parts of that unit but not the regulator. The fuel cooler has a pressure test port on one of the fittings.
 

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Discussion Starter #3
The horozontal fuel conditioning module , HFCM, is the fuel filter housing under truck and has the electric fuel pump and also has the low pressure fuel system pressure regulator. Since the cap swells when key is switched to run position w/0 engine run, the pressure regulator there must have a problem is letting the pressure go way too high. The pressure should be about 25 psi. I have not had an HFCM on a 6.4 give me any problems so I have not investigated that regulator and the only illustratiions of the HFCM show lots of parts of that unit but not the regulator. The fuel cooler has a pressure test port on one of the fittings.
Thanks for the reply. The test port on the cooler is where I’m getting 90psi. Engine not running key on fuel pump on cap swells. I’m going to take the HFCM apart I guess.
 

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Discussion Starter #4 (Edited by Moderator)
Update
The HFCM was sending to much line pressure to the secondary fuel filter. I replaced the HFCM and now have the correct pressures at the valve on the cooler. I took the old one apart and there’s pebbles gel and other gunk in it.
Salty
 
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