1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.

Regulator on the return side???

Discussion in '6.9L IH & 7.3L IDI Diesels' started by laserjock, Feb 22, 2021.

  1. laserjock

    laserjock Almost there... Supporting Member

    Posts:
    8,784
    Likes Received:
    3,004
    Joined:
    Nov 20, 2012
    Location:
    Maryland
    Okay. I’m going toss this out there. I know there’s been a lot of hate on the Facet pumps of late. I totally understand why. Not trying to debate the merits of the different pumps. We’ve beat that horse to death 50 different ways. The fundamental problem is not enough flow. To maintain steady pressure to the IP.

    So random brain fart for the day. There is a significant amount of fuel just returning to the tank. To the best of my understanding, that results from the plumbing of the return system and there’s really nothing to keep it from flowing aside from the tubing and the little duck-Bill valve in the tank. Could putting a regulator on the return side of the system so that when demand increases it could restrict the return flow and maintain system pressure be a solution? Aside from maybe causing leaky caps, what other implications would a couple psi of head pressure have on the pump and injectors?


    I’ll crawl back over here and go back to sleep now.
     
  2. hacked89

    hacked89 Full Access Member

    Posts:
    450
    Likes Received:
    530
    Joined:
    May 30, 2018
    Location:
    Bucks County PA
    Hey man. Return system is for cooling as well as removing unused fuel and air from the system. The return system is suppose to be under slight vacuum to prevent drain back and accomplish this. That's why air intrusion on the return side could also cause hard start. I would not suggest reversing the system with positive pressure. Only downsides.

    Also your problem statement is supply side instability and you seem to be asking if it should be attempted to correct it on return side.

    You can overcome alot of stability issues by having the right size supply side vs psi vs regulating right before the IP. I went into it in detail in the fuel math thread so I don't want to clog up yours.

    Sent from my SM-G955U using Tapatalk
     
  3. IDIBRONCO

    IDIBRONCO IDIBRONCO

    Posts:
    7,264
    Likes Received:
    5,473
    Joined:
    Feb 5, 2010
    Location:
    edmond, ks
    I agree with this.
     
  4. Philip1

    Philip1 Supporting Member Supporting Member

    Posts:
    398
    Likes Received:
    329
    Joined:
    Apr 1, 2019
    Location:
    Northeastern Nevada
    From what I understand on how the system works, the return system relieves pressure that bled past metal to metal sealing surfaces. For example, the injectors have a small amount of fuel that bleeds past the pintle valve inside. This would put more pressure on the back side of the valve making it harder for the injector to open. On the injection pump my knowledge is lacking a bit more, however the same principle applies in addition to the fuel that must be returned for the hydraulic advance to work. It takes a very small amount of back pressure on the ip to cause the timing to get off track and if the back pressure gets high enough it would prevent the ip from delivering enough fuel due to the internals of the ip being prevented from returning to its starting point.
     
    The_Josh_Bear and IDIBRONCO like this.
  5. IDIBRONCO

    IDIBRONCO IDIBRONCO

    Posts:
    7,264
    Likes Received:
    5,473
    Joined:
    Feb 5, 2010
    Location:
    edmond, ks
    I like this one. I feel that it a very good explanation.:cheers:
     
  6. mblaney

    mblaney Full Access Member

    Posts:
    1,087
    Likes Received:
    335
    Joined:
    Dec 7, 2012
    Location:
    Ottawa/Ont/Canada
    Put a clamp on the filter head return line and you will restrict a lot of return flow without affecting anything else. My Walbro pump I can adjust from maybe 4 pulses per second to 1 every (make up a number). I find it hard to believe that almost ANY fuel pump could not be usable.

    I am guessing the filter bleed passes 90% of the returned fuel - that is a lot of demand on the pump for nothing, unless you have a huge air leak on the intake side.
     
  7. laserjock

    laserjock Almost there... Supporting Member

    Posts:
    8,784
    Likes Received:
    3,004
    Joined:
    Nov 20, 2012
    Location:
    Maryland
    This was my general thought as well. Interesting thought restricting it at the filter. An orifice there carefully selected might be interesting. At the end of the day it’s a hydraulic system. There are ways to manipulate flows. Does it make sense to try??? Who knows. Just wanted to have a discussion.

    I’m going to chew on it a bit. If I have any epiphanies I’ll update.

    Thanks guys.
     
    SLC97SR5 likes this.
  8. chillman88

    chillman88 Supporting Member Supporting Member

    Posts:
    4,369
    Likes Received:
    3,541
    Joined:
    Feb 22, 2017
    Location:
    Central NY
    I've had my filter return completely plugged on both of my trucks for almost as long as I've owned them. I've never had a drain back issue even with leaking caps. So for what it's worth, plugging the filter return might just help. You could always just put a ball valve inline in case you need to bleed the filter.
     
  9. typ4

    typ4 Supporting Member Supporting Member

    Age:
    60
    Posts:
    8,833
    Likes Received:
    978
    Joined:
    Dec 24, 2005
    Location:
    Newberg,OR
    The fitting on the filter for the return should have an orifice in it already.
    it's mainly there to get any air bubbles out of the top of the fuel filter before the fuel gets to the IP
     
  10. Ironman03R

    Ironman03R Full Access Member

    Age:
    37
    Posts:
    2,193
    Likes Received:
    126
    Joined:
    Jan 8, 2006
    Location:
    Risingsun, OH (NW OH)
    I remember my thoughts on that pump years ago were the ports were to small to support the fuel volume needed. Could the pump be disassembled and the ports drilled and threaded to a larger size to allow more volume?
     
  11. laserjock

    laserjock Almost there... Supporting Member

    Posts:
    8,784
    Likes Received:
    3,004
    Joined:
    Nov 20, 2012
    Location:
    Maryland
    I have considered that as well.

    I think I have a plan. Updates coming soon.

     

Share This Page