EFI Fuel Circulating Question.....
+ Reply to Thread
Page 1 of 2 1 2 LastLast
Results 1 to 14 of 17

Thread:
EFI Fuel Circulating Question.....

  1. #1
    Senior Member Notalent's Avatar
    Join Date
    Jan 2008
    Location
    Dallas/HB/LBC
    Posts
    1,081

    Default EFI Fuel Circulating Question.....

    What exactly is a recirculating system and how does it work? Does the fuel dump back into the tank? I heard you can return it through the pump and also to the water seperator.

    Inform me please.
    "Pain is a figment of your Imagination"

  2. Remove Advertisements
    PerformanceBoats.com
    Advertisements
     

  3. #2
    steelcomp was here
    Join Date
    Dec 2007
    Location
    n/e TN
    Posts
    26,280

    Default

    Quote Originally Posted by Notalent View Post
    What exactly is a recirculating system and how does it work? Does the fuel dump back into the tank? I heard you can return it through the pump and also to the water seperator.

    Inform me please.
    A recirculating system is exactly that...the fuel is supplied at a constant pressure via (typically) electric pump. The engine uses what it needs, and what it dosen't use, bypasses the system and returns to the tank. The fuel is constantly circulating. Obviously at idle, there's more fuel bypassing the system than at WOT. The fuel can be returned anywhere on the supply side of the pump or back in to the tank.
    If God is your co-pilot, change seats!
    Acts 2:38, the perfect answer to the perfect question.

  4. #3
    Senior Member Notalent's Avatar
    Join Date
    Jan 2008
    Location
    Dallas/HB/LBC
    Posts
    1,081

    Default

    Quote Originally Posted by steelcomp View Post
    A recirculating system is exactly that...the fuel is supplied at a constant pressure via (typically) electric pump. The engine uses what it needs, and what it dosen't use, bypasses the system and returns to the tank. The fuel is constantly circulating. Obviously at idle, there's more fuel bypassing the system than at WOT. The fuel can be returned anywhere on the supply side of the pump or back in to the tank.
    Is there any reason why it wouldnt be able to dump back into the fuel tank?

    Thanks for the info.
    "Pain is a figment of your Imagination"

  5. Remove Advertisements
    PerformanceBoats.com
    Advertisements
     

  6. #4
    steelcomp was here
    Join Date
    Dec 2007
    Location
    n/e TN
    Posts
    26,280

    Default

    Quote Originally Posted by Notalent View Post
    Is there any reason why it wouldnt be able to dump back into the fuel tank?

    Thanks for the info.
    No, as long as you're running one tank. If it's a boat with two side tanks, it can be a problem with only one return line.
    If God is your co-pilot, change seats!
    Acts 2:38, the perfect answer to the perfect question.

  7. #5
    Senior Member oldschool's Avatar
    Join Date
    Dec 2007
    Posts
    762

    Default

    If your returning to the tanks just run your return line to a tank selector valve(just one to switch from left to right). From there you just make sure your returning from the same tank your pulling from.

  8. #6
    21 Daytona Outlaw's Avatar
    Join Date
    Dec 2007
    Location
    Artesia, N.M.
    Posts
    5,291

    Default

    IMCO makes a really nice fuel selector switch/valve
    made just for EFI. 6 port. 1/2 " it swiches feed and return and
    sending units. pricey but nice

    http://www.danamarineproducts.com/Pr...TOKEN=59965491

  9. #7
    No Sandbar To Far sanger rat's Avatar
    Join Date
    Dec 2007
    Location
    MI
    Posts
    3,276

    Default

    I just split the lines back to the tanks. -10 to the regulator -8 out to two -6 lines. Never had a problem with tanks not being equal.
    Quote Originally Posted by One More Year View Post
    The only blab's I will even be a part of is just when it is me they are talking about. Aaaah yes I can see a few good looking shiny tall deck motors on the beach, with barely enough fuel to get back to the launch saying, "Holy crap how fast you think that Daytona was going man? That's like the 20th time he's gone by today?"

  10. #8
    Senior Member Notalent's Avatar
    Join Date
    Jan 2008
    Location
    Dallas/HB/LBC
    Posts
    1,081

    Default

    The customer im dealing with says that his tank does not have a return into the tank and noone will weld one in.....what happens in this case....? Will the IMCO Fuel Valve fix the dilemna?
    Last edited by Notalent; 02-20-2008 at 07:12 AM.
    "Pain is a figment of your Imagination"

  11. #9
    cfm
    cfm is offline
    Banned
    Join Date
    Jan 2008
    Posts
    1,263

    Default

    A lot of people return it back to the water seperator. Use one that has 4 ports (2 outlets, 2 inlets) and mount the pump after (and lower) the seperator. Use a normal fuel filter after pump.

    Mercruiser does this also, but uses a fuel cooler (looks + is like small oil cooler) to make sure there is no fuel heating issues.

    I have not done the above, but I have done the following on single tank applications : http://www.cpperformance.com/SearchR...CategoryID=379

    The fuel fill hoses I did these in where 2" ID. If you don't have this fill hose ID nor single tank, then this won't work for you.

  12. #10
    21 Daytona Outlaw's Avatar
    Join Date
    Dec 2007
    Location
    Artesia, N.M.
    Posts
    5,291

    Default

    Quote Originally Posted by Notalent View Post
    The customer im dealing with says that his tank does not have a return into the tank and noone will weld one in.....what happens in this case....? Will the IMCO Fuel Valve fix the dilemna?
    It is best to get the return fuel back to the tank. IMO

  13. #11
    Wishin I was at the lake! Brian's Avatar
    Join Date
    Dec 2007
    Location
    Cave Creek, AZ
    Posts
    547

    Default

    Quote Originally Posted by Notalent View Post
    The customer im dealing with says that his tank does not have a return into the tank and noone will weld one in.....what happens in this case....? Will the IMCO Fuel Valve fix the dilemna?
    Uh, no. Returning to separator is best solution in this case. IMCO valve just allows you to switch between feed & return, but if the tank(s) has no return(s), you still need to go with something different. Big separator filter is best alternative to give most thermal mass to dissipate heat before reaching the carb/injectors. Not such a problem with smaller pumps, but the big high pressure EFI pumps can run pretty warm and add significant heat to the fuel.

  14. #12
    Senior Member STV_Keith's Avatar
    Join Date
    Dec 2007
    Location
    Lost Wages, NV
    Posts
    2,145

    Default

    Here I put a tank fill and return hose point into my fuel tank. The return is a 3/4" bushing with a 1/4" NPT on the top, which connects to a 5/16" hose barb.



    The original return was into a y-fitting on the fuel tank fill.
    Keith-


  15. #13
    !%@#$ Racer52's Avatar
    Join Date
    Dec 2007
    Location
    Stockton, CA
    Posts
    508

    Default

    I have been returning through a fuel cooler and then back to the water seperator. Never had an issue and the fuel going to the pump is always cooled somewhat from the -6 or -8 return line.

    Did this due to the duel tank issue and no bungs in the tank for return lines.


    Racer

  16. #14
    It's what we do BDMarine's Avatar
    Join Date
    Dec 2007
    Location
    El Monte
    Posts
    723

    Default

    The problem with returning the fuel to the seperator is that in July at Havasu the chance for vapor lock is very high. I had that problem all last summer. I am in the process of moving the returns to the tank fills with something similar to the ones shown earlier in this thread from CP. In a single engine/dual tank when it has already had fuel in it, make a flange with a return bung welded into it, it will look similar to a fuel sending unit. Make a gasket (fuel safe) and screw it to the top of the tank away from the pick-up. Then use the Imco 6 port fuel valve, 2 for the supply and 2 for the return. (liability disclaimer) Make sure the return is completely sealed with a gasket at the flange and where the screws go into the tank.
    http://www.performanceboats.com//signaturepics/sigpic837_1.gif
    B & D Marine Performance
    El Monte, Ca.

+ Reply to Thread
Page 1 of 2 1 2 LastLast

Quick Reply Quick Reply

Register Now

Please enter the name by which you would like to log-in and be known on this site.

Please enter a password for your user account. Note that passwords are case-sensitive.

Please enter a valid email address for yourself.

Please select your insurance company (Optional)

Log-in

Tags for this Thread

Digg This Thread

Posting Permissions

  • You may post new threads
  • You may post replies
  • You may not post attachments
  • You may not edit your posts
  •  
 

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95