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  1. #1

    Join Date
    Jul 2015
    Posts
    9
    Location
    New Hampshire
    Mower
    Craftsman

    How to bypass B&S twin opposed fuel pump

    This 16 hp machine eats pump diaphragms yearly due to what passes for gas here in NH and since the gas tank is higher than the pump inlet Id like to bypass it entirely and not get gas into the crankcase. Can I just clamp off/block that vacuum line or is it more complicated?

    Geoff

  2. #2
    tom3's Avatar
    Join Date
    Apr 2018
    Posts
    441
    Location
    Ohio
    Mower
    John Deere

    Re: How to bypass B&S twin opposed fuel pump

    I think the crankcase is actually vented through the air cleaner, but to be safe I'd probably leave the vacuum line attached to the pump and just run the fuel lines together. Not real sure how the pump gets any vacuum out of a crankcase anyway. Fuel pressure is about nothing anyway so the gravity feed should work with a nearly full tank.

  3. #3

    Join Date
    Mar 2012
    Posts
    8,205
    Location
    Wisconsin
    Mower
    Toro

    Re: How to bypass B&S twin opposed fuel pump

    This may or may not work. The thing people donít realize is that there are different carbs and needles when you have engines with or without pumps. Some need the pressure of the pump to keep the proper amount of fuel in the float bowl. The pump supplies more pressure that most people think, plus may be needed if the unit is used on hills and slopes.
    This is only my opinion, and many will say it ain't worth a darn, as I'm only a retired grease monkey instructor and not a professional mechanic. Use what I post at your own risk as you know teachers only know book knowledge.

  4. #4

    Join Date
    Jul 2015
    Posts
    9
    Location
    New Hampshire
    Mower
    Craftsman

    Re: How to bypass B&S twin opposed fuel pump

    It is my understanding that these engines get fuel pump vacuum from a port on the block and the crankcase breather is what goes to the air cleaner.
    Similar to my 68 Impala SS 396 ragtop

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