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Thread: Fuel pressure drops during startup and car won't start.

  1. #1

    Default Fuel pressure drops during startup and car won't start.

    I watch the the fuel pressure and as soon as the Dominator syncs while it's cranking, the fuel pressure drops from 43 psi to 18-20 psi and will not fire. I have a return system with a Aeromotive fuel pressure regulator and a Pro Series 11102 fuel pump setup for E85 and I have a pump controller. I also have FIC 1700 multi-fuel injectors. The car normally fires right up after my Dominator syncs. I've never watched the fuel pressure closely during startup, but I assume this is not normal. I was just sitting in line ready to make the first pass this year and the car died while idling. It never does that. Have drove maybe 50 miles on the street this year with no problems. I've got it to fire once or twice sense and it dies immediately. Would a bad injector do this? I haven't taken the car off the trailer to troubleshoot yet.

  2. #2
    Join Date
    Dec 2009
    Location
    Connecticut
    Posts
    27,045

    Default

    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.).
    Maybe you've already done this, but 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.
    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)
    May God's grace bless you in the Lord Jesus Christ.
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  3. #3

    Default

    Good place to start anyway. Of coarse I filled up my tank yesterday. I have both the pre & post filters. The fuel pump is under the tank with a
    direct line coming from the bottom of the tank.

    The pump will occationally make some odd noises, but I haven't noticed it this year. If filters are clean I may remove the elements temporarily and see if it holds pressure.

  4. #4

    Default

    100 micron filter had two tiny specs of what looks like silicone grease. 10 micron filter was spotless.

    My tuner replied with this: "It's definitely not normal. A datalog set to start with the RPM at 100 and several seconds long would be helpful along with your current Global Folder."

    Am I wrong to assume pump, injectors, or regulator are probably the cause?

  5. #5

    Default

    It wasn't this obvious the other night at the track, but the pump sure doesn't sound good now.
    https://youtu.be/SqIbcbUjSls

  6. #6
    Join Date
    Nov 2014
    Location
    Ont. Canada
    Posts
    1,706

    Default

    Change your Fuel Pump Prime to 600 seconds and let the pump run with the key-on/engine-off. What results do you get?

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