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1996 5.7L Fuel Pulsation Dampener

Discussion in 'Chevy C/K Truck Forum' started by ImpetuousNinja, Feb 20, 2012.

  1. ImpetuousNinja

    ImpetuousNinja New Member


    I have a 1996 Chevrolet Silverado with a 5.7L Vortec. A few years ago it simply quit running while I was driving down the freeway at 70 mph. I had to have it towed to a shop to get it repaired because I was 400 miles from home. The mechanic told me he replaced the FP30 fuel pulse dampener located on the fuel sending unit. Everything worked fine after that. (I replaced the fuel pump and filter two years previously.)

    Question 1: What exactly does the dampener do that would cause a loss of fuel pressure? My understanding is that the pressure regulator should be responsible for pressure while the dampener simply 'smooths' out the pressure by eliminating the pulses.

    Question 2: Why are there pulses in the first place? I'm assuming the electric fuel pump produces a relatively steady rate of pressure, so are the pulses due to the injectors operating?

    Thank you in advance!
  2. MrShorty

    MrShorty Epic Member Staff Member 5+ Years 1000 Posts

    Do you have a picture or some other documentation regarding this alleged part? Is it part of the fuel pump assembly (I have my old assembly at home) or is it elsewhere in the fuel system?

    Granted my experience is relatively limited, but this is the first "pulse dampener" I've heard of on a continuously circulating fuel system like ours.

    An intriguing mystery???
  3. ImpetuousNinja

    ImpetuousNinja New Member

    Thank you for your response!

    I was able to find the part on; it's an ACDelco FP 30 Fuel Pulse Dampener (link). The work order given to me by the mechanic had this part number listed. Here's a picture from Amazon:

    ACDelco FP30.jpg

    The dampener is attached to the pipe on the fuel sending unit right above the fuel pump. I was helping a buddy replace his fuel pump in an old Pontiac Grand Am this past weekend and noticed the same part on his sending unit, so I decided to do some research.

    The mechanic told me that even though the fuel pump was working fine, the dampener prevented the system from building up enough pressure to open the injectors. I know he didn't do any work inside the engine compartment, so it's safe to assume he didn't replace the pressure regulator. Also, he cracked a pipe on the sending unit which I found the next day when I literally watched my gas gauge go down as I was driving and could see gas spraying out from the underside of the box when stopped at a light. Consequently, I know he was working with the sending unit.

    Thanks again!

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