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Thread: Squeal under heavy load.

  1. #1

    Default Squeal under heavy load.

    New Sniper setup in my 427 Cobra. Idles fast, but otherwise runs good. I do notice a loud squeal coming from the 19-350 fuel pump area under heavy acceleration, goes away when I let off the pedal. Is this normal for a fuel pump or what's going on?

  2. #2
    Join Date
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    This is a copy & paste of one of my other posts:
    Originally Posted by Danny Cabral
    A loud fuel pump is usually an indication of fuel pump cavitation or maybe a clogged filter(s). Inspect/troubleshoot/service the fuel system (fuel pump, cavitation, plumbing, voltage, filters, pickup tube, tank venting, etc.). A datalog will just verify a problem with the fuel pressure, injector duty cycle, pulse width, etc.

    An EFI fuel system needs two filters:
    Before fuel pump - 100 micron pre-filter. (Or the OEM in-tank sock filter.)
    After fuel pump - 10 micron post-filter. (40 micron is for carburetion.)
    The 40 micron (carburetor) fuel filter has no place on an EFI fuel system. (I know you're not using it.)
    It's too "fine" of a filter to be used before the pump, causing fuel pump cavitation.
    FYI: The sock filter (HydraMat or OEM) of an in-tank fuel pump, is the pre-filter. Don't add another one.
    http://documents.holley.com/holleyfu...ems_chart1.pdf (Fuel System Selection Chart)
    http://documents.holley.com/flyer_ho...el_systems.pdf (Holley Fuel Systems Brochure)
    https://forums.holley.com/showthread...395#post223395 (Related Forum Thread - NAPA 20 Micron Pre-Filter)
    Contact Chris Myer at EFISystemPro.com. He's a Holley EFI parts professional, Holley EFI Dealer & fuel pump/fuel system specialist.

  3. #3

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    So I have the proper pre & post filter setup. It has a 100 micron in the tank and a 10 micron (162-554) before the EFI unit. The fuel lines are mostly hard copper/nickel with braided stainless to connect the ends. The fuel pump is connected to a short run of braided stainless that connects to hard copper/nickel. The first three feet of the hard copper nickel has several 90° bends in it that work around frame rails. It was bent with a tubing bender so there’s nothing that has an acute angle, but it still is several 90° bends. I wonder if this is causing the problem?

  4. #4
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    Quote Originally Posted by aarvig View Post
    The first three feet of the hard copper nickel has several 90° bends in it that work around frame rails. It was bent with a tubing bender so there’s nothing that has an acute angle, but it still is several 90° bends. I wonder if this is causing the problem?
    I doubt it, especially after the fuel pump. Refer back to post #2 above (there's more to check).
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: 385"/6.3L SBF, Dart SHP 8.2 block, forged steel crank & rods, forged pistons, Trick Flow T/W 11R 205 CNC comp ported heads, 12:1 comp ratio, 232°-244° duration/.623" lift/114° LSA camshaft, TFS R-Series FTI comp ported intake, BBK 80mm T/B, Holley Dominator MPFI & DIS, Holley 36-1 crank trigger, MSD 1x cam sync, PA PMGR starter, PA 200A 3G alternator, Optima Red battery, 100HP progressive dry direct-port NOS, R134a A/C, Spal dual 12" fans, Frostbite 3-core aluminum radiator, Pypes dual 2.5" exhaust, off-road X-pipe, shorty headers, Earl's -6AN fuel system plumbing, Walbro 255 LPH in-tank pump & Pro-M -6AN hanger, S&W subframe connectors, BMR upper & lower torque box reinforcements, LenTech Strip Terminator wide-ratio AOD, 3000 RPM C6 converter, B&M Hammer shifter, Stifflers transmission crossmember & driveshaft safety loop, FPP aluminum driveshaft, FPP 3.31 gears, Cobra Trac-Lok differential, Moser 31 spline axles, '04 Cobra 4-disc brakes, '93 Cobra booster & M/C, 5-lug Bullitt wheels & 245/45R17 M/T Street Comp tires.

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