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Thread: Fuel Pump Problems

  1. #1

    Default Fuel Pump Problems

    Good afternoon everyone. Well, finally got my Dominator equipped car running, and I'm so happy with it. (Thank you Danny!) It runs very good, and even with a big cam it'll idle right down to 800 RPM. Anyway, while it runs great, after about 10 minutes of running, the fuel pump is as loud as the car. It starts out quiet. It's a Weldon 1100A Pump (approximately 130-140 GPH (which computes to 492 LPH), and my engine makes about 840 HP. I have a 100 micron Filter before the pump and a 10 micron after (they are clean). I'm running a Hilborn Stack Injector, and Hilborn equipped the fuel rails with -8 ORB to AN fittings, so I plumbed the car with .0410 ID (-8) stainless fuel line. I have a Weldon Fuel Pump controller that isn't working, but have another on order. This is to be able to have full flow or dial it back. I have a stainless fuel tank, and the fuel pressure never falters from 43 psi. I isolated the return line (when the pump was noisy), and put the return direct out of the regulator to a 5 gallon bucket (and filled it). The pump stays noisy. It appears to me that the problem is on the pressure side (?), causing the pump to cavitate. I just replaced the suction hose from the tank to pump (two 45° fittings in that line), or, is it possible that my pump is simply too big and "stacking up"? This all happens at idle. Could I have a bad pump? If it were "sucking air" it'd be before the Pump correct? And leaking after, I have no leaks, and, again I just replaced that suction hose. I'm at a loss as what to do. My Tank is equipped with the option to run an in-tank pump, and the tank manufacturer can make me an A340 or A450 Aeromotive pump to fit. Or, I can replumb the whole Car in -10 (or both)? I'm really looking for some help and experience here, as I don't know what to do next. Thanks for your help.

  2. #2
    Join Date
    Dec 2009


    This is just a copy & paste of one of my other posts:
    A loud fuel pump is usually an indication 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. (Fuel System Selection Chart) (Holley Fuel Systems Brochure)
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: 385" SBF, Dart SHP 8.2 block, TFS T/W 11R 205 heads, 232°-244° duration/.623" lift/114° LSA camshaft, 12:1 C/R, TFS R-Series FTI ported intake, BBK 80mm T/B, Dominator MPFI & DIS, 36-1 crank trigger/1x cam sync, 200A 3G alternator, Optima Red battery, A/C, 100HP progressive dry direct-port NOS, Spal dual 12" fans/3-core Frostbite aluminum radiator, Pypes dual 2.5" exhaust/off-road X-pipe/shorty headers, -6AN fuel system plumbing, Walbro 255 LPH pump, S&W subframe connectors, LenTech Strip Terminator wide-ratio AOD/3000 RPM converter, B&M Hammer shifter, 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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