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My truck has fresh filters and the blue spring upgrade when idling I have about 58-60 PSI measured from the test port at the regulator. When I hit WOT with my 8K tow tune from Gearhead and Atlas 40 FCIM tunes it can drop down to about 38 PSI if I just stay on it. I am guessing my HFCM is just getting weak but is there anything else I should check first? When the HFCM fails do they usually just keep getting weaker or do the just totally fail? I am taking the truck on about a 600 mile trip next week and I am hoping to just keep an eye on the pressure and not run it hard enough to drop the pressure down below 45. Where is a good place to get a new HFCM other than the dealer? I might just go with an Airdog II if it isn't way more than the stock part. Thanks!
when i was troubleshooting my low fuel pressure issue i had the HFCM apart and found there is a relief valve inside along with the orings/seals and a cover gasket that could all go bad and cause problems.. for my piece of mind it was just easier to change the whole thing and take those possible problems out of the equation. that is a great price on just the pump tho.
Well I did the blue spring about a month ago. What else would be wrong with the regulator? I actually just connected the dots that it currently has less than 1/4 tank and I have never seen the pressure drop below 45 PSI before and since the truck is pretty new to me I don't have a lot of history with it. I am betting that when I really get into it the fuel is sloshing to the back of the tank and the HFCM is not getting a good supply and thus causing a drop until I let off a bit so that the fuel shifts back to the bottom of the tank. Is that something that seem possible? Tonight I will just fill it up and take if back out and see if I can get the pressure to drop with a full tank but I am hoping not.
With all of the posts I have seen about adding a fuel sump it seems like this must be a common occurrence.
Fuel sump, 6.7 pump and regulated return. $500 solution to a $100 problem, but if you plan on any mods in the future, it may be worth it to get the fuel system put to bed.
Changing just the spring isn't enough. I had one that when I changed just a spring it caused the regulator conical seal to fail, bypassing fuel. At 75% throttle it would dip to 35 to 40 psi. Pretty nerve racking while towing 12k 5er in the Tennessee mountains. A new regulator kit cured it and now holds 68 idle.
Yeah, I did the regulator kit, I replaced most everything except a couple orings because I couldn't get the hose adapter out of the old cover so I reused the old cover. I replaced the spring and the brass cone from your picture and the little white thing. After I filled the truck up it seems to have fixed it. 58-60 at idle and 50 WOT. In the future I think I'll do a sump with an airdog supplying the HFCM and regulated return. For now I'll just keep it over a 1/4 tank and watch my pressure.
Debris in the HFCM is another possibility from using non oem filters, you can rip it apart, pull the side cover off and clean out junk in there. there are some small parts behind the cover that I had junk in. cleaned and blew out with compressed air. Don't remove the o-ring from the pipe the filter goes over unless its damaged and you have another. the spring loaded portion will fly out and you'll uncover one hell of a reassembly puzzle and another o-ring that will most likely get damages in the process.
If you drop your tank to replace the pickup screen, good time to harpoon it so you'll get a fast and complete fill
