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  1. #1

    Default 1996 5.7L Fuel Pulsation Dampener

    Hi:

    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. #2

    Default

    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???
    '98 K1500 Suburban LS 5.7 L 4L60E NV246 ARB
    '92 Ford Explorer XLT 4x4 4.0 L A4LD BW13-54 Trac-loc rear
    "My toys were the greasy cogs and springs and pistons that lay around all over the place, and these, I can promise you, were far more fun to play with than most of the plastic rubbish children are given nowadays." Danny in Roald Dahl's Danny The Champion of the World

  3. #3

    Default

    Quote Originally Posted by MrShorty View Post
    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???
    Thank you for your response!

    I was able to find the part on Amazon.com; 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:

    Click image for larger version. 

Name:	ACDelco FP30.jpg 
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    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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