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  1. Join Date
    Oct 2002
    Posts
    29,320
    #1
    Is there a potential link to use of Auto-LPG and fuel pump failure?

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    In some of our vehicles, an electrical relay was installed to activate/deactivate the fuel pump when LPG system was off or on. This was meant as a preventive measure because it has been observed in some vehicles that even with the LPG system running, gasoline (under pressure) is leaking through the closed fuel injectors. I am curious adding the relay can cause a condition for the fuel pump to fail prematurely?

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    I am also concerned with a potential problem with Auto-LPG use with cars with returnless fuel systems. Since there is no traditional fuel return line, the fuel is not moving and yet the pump is keeping the pressure in the fuel line. Will this static pump pressure condition have a potential to lead to premature pump failure?

  2. Join Date
    Mar 2006
    Posts
    607
    #2
    with properly installed lpg conversion kit, this shouldn't be an issue .

  3. Join Date
    Oct 2002
    Posts
    29,320
    #3
    Quote Originally Posted by bambino View Post
    with properly installed lpg conversion kit, this shouldn't be an issue .
    And what does that mean? Properly installed lpg conversion kit? Does it mean it comes with a relay to cut off power to the fuel pump or not? Most kits do not have relays to cut power to the pump.

  4. Join Date
    Mar 2006
    Posts
    607
    #4
    the pump for the returnless fuel systems are designed to stand let's say constant 55-64psi ( GM 4.3L VORTEC ENGINES)

    so i don't think it's a concern at all

    unless there really was a problem on the injectors in the first place

  5. Join Date
    Jun 2006
    Posts
    6,105
    #5
    Logically, it might pose a problem. Since the fuel pump wasn't designed to produce and contain very high pressure (unless it has a pressure switch like the ones installed in household and industrial water pumps).

    the best thing to do is cut off the power to the pump.

  6. Join Date
    Oct 2002
    Posts
    29,320
    #6
    Quote Originally Posted by bambino View Post
    the pump for the returnless fuel systems are designed to stand let's say constant 55-64psi ( GM 4.3L VORTEC ENGINES)

    so i don't think it's a concern at all

    unless there really was a problem on the injectors in the first place
    The concern is the fuel system might be rated for 55psi but that is flowing, not static pressure which can induce higher stress to the pump itself.

  7. Join Date
    Mar 2006
    Posts
    607
    #7
    if you want to know more about returnless fuel systems just let me know .

    and if you happen to personally experience openning a gas tank with returnless, you will know more that the pump itself has a regulator built-in to it .there is even has a pressure sensor built - in too.

    i have all kinds of technical info regarding of fixing cars , and i have the info available to your questions.

    what i just want to say is the simpliest way to understand , but if you want to know the ins-and outs, let me know

    i do a fleet maintainance to the taxis around ( CANADA) and these have a dual fuel systems ( PROPANE/GASOLINE) and how we do it is a little bit different . we are licenced to do those systems . we don't have to cut the fuel pumps off. it's running all the time the engine runs .

    so i'm going back to my first post , it's not a concern at all.


    but if you still want to cancel the fuel pump while on lpg, it's just simple ,
    you can have the original fuel pump relay cut with on/ off switch.you don't need another relay.

    there are cases that the ecm can sense the faulty circuit so you may have to live with it

  8. Join Date
    Aug 2008
    Posts
    7
    #8
    Help!

    Ive been using LPG for 5 or so months straight, didnt use the gasoline

    Now when I tried gasoline it will not start at all. (the Gaso tank has been empty for a few months before i filled it again)

    The mechanic said, goodbye fuel pump and nozzles; but new ones

    Is there any ideas from you folks?

    thank you

  9. Join Date
    Oct 2002
    Posts
    29,320
    #9
    Quote Originally Posted by rpxhost View Post
    Help!

    Ive been using LPG for 5 or so months straight, didnt use the gasoline

    Now when I tried gasoline it will not start at all. (the Gaso tank has been empty for a few months before i filled it again)

    The mechanic said, goodbye fuel pump and nozzles; but new ones

    Is there any ideas from you folks?

    thank you
    You can replace the busted fuel pump motor with a replacement motor.

    And then add a relay to disable the motor whenever you are using LPG.

  10. Join Date
    Aug 2008
    Posts
    7
    #10
    1. Are you saying the Fuel pump gets broken that way and is now actually broken?

    2. adding a relay?

    3. That will cost me something like P5,000? in all?

    if I had known.............

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Auto-LPG and fuel pump failure ??