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Thread: Sniper in-line fuel pump replaced. Screeching continues.

  1. #1

    Default Sniper in-line fuel pump replaced. Screeching continues.

    My daughter had the truck die on her two days ago. She was able to restart a few minutes later and get home. I started it when she got home and the pump started screeching and then the truck died. Repeated this a couple times. Next morning, started right up, but only able to move the truck out of the driveway before the same screeching and fuel loss happened. I was not able to restart and have enough fuel to keep running. I had a new Walbro 255 pump shipped overnight from Summit. Replaced the pump, started the truck and pump started squealing within 30 seconds. It sounds to me like it’s starving and the scenarios suggest the pre-filter is clogged. This would explain how it’s acting. However, this setup only has a couple hundred miles on it and my gas tank is VERY clean. Have there been a documented bad batch of pre-filters? I’m going to change the filter and expect the problem to go away, but I’m open to suggestions. The only other thread I found on this issue was a guy that removed the filter altogether...I’m not about to do that.

  2. #2
    Join Date
    Nov 2014
    Location
    Ont. Canada
    Posts
    1,200

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    An electric fuel pump is good at pushing fuel, but not so good at pulling fuel. It sounds like you have too much restriction before the pump and the pump is cavitating. Once the pump and fuel cool off it will usually work for a short period of time before it starts to do it again. Once it starts doing this, it only gets worse and burns up the pump.

  3. #3

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    Yeah, we’ve established that already. Clearly, the pre-filter is the restriction. My tank is very clean, no corrosion or sediment of any kind. Thinks makes me believe the filter is internally collapsed or otherwise defective. Hence, my question above.

    This is a 1970 F100 with an in-cab fuel tank. The line comes out of the bottom and directly into the filter, followed by the pump and post filter, all mounted on the frame. If I pull the hose from the inlet of the pre-filter, fuel will aggressively drain, as it’s sitting below 15 gallons of fuel. Fuel supply is not the issue.

  4. #4

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    Do you have a sock on the pickup in the tank? That could be an issue as well.

  5. #5

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    There might be air getting into the pickup. Where is your return line returning fuel to the tank? Above the fuel line or low down in the tank (away from your pickup)? If it's above the fuel line, it will aerate the fuel causing air to be pulled through the pump. You indicate after the car had settled, that it can start and is quiet for a while before the noise returns. Air in the system will present in the same way. Aeration in fuel dissipates when left alone, then with the pump is running, return fuel is mixing air into the tank.

    I heard horror stories about noisy inline pumps prior to my installation. To minimize any of those issues occurring with my installation, I've added a Holley HydraMat (the largest I could fit through my existing tanks pickup hole). From what I've seen, the HydraMat will prevent air pickup and becomes the pre-filter for the pump. As a test, can you run a clear pickup fuel line between your tank and input side of your fuel pump? (make sure the clear tube is fuel safe) Run the car and observe the fuel in the clear pickup. Is air present during noisy operation or does the fuel flow visually change between normal and noisy pump operation? Gary.
    351 Cleveland
    Holley Sniper EFI 4150 Super Sniper 650 with HyperSpark Ignition.

  6. #6

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    More points to clarify: This truck has been running fine for a couple hundred miles. No issues of this type until now. The return line is a 3/8" Teflon tube, dispensing at the bottom of the tank. I’m going to remove the pre-filter tomorrow temporarily and see what happens. I’m expecting it will run fine.

  7. #7

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    I lost my fuel pump just a couple hundred miles in as well. Started squealing then the truck died. Summit overnighted me a new pump which has worked fine so far. I relocated the second pump right onto the bottom of the fuel tank rock guard to try to get it closer than the original, which was just 2' away and still below the tank. I installed the original per the instructions, it just didn't last.

    I installed new Wix filters on the 2nd pump just as a precaution and never really checked them for any kind of blockage before tossing them in the trash.

    I'd definitely pull your pre-filter and test without it to see if it eliminates your problem. And make sure the pump isn't located anywhere near your exhaust which would generate too much heat for the pump. If I lose another, I'm going to request that Summit upgrade me to an in-tank pump.

  8. #8

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    You can jump your fuel pump relay and run the fuel system without running the engine. Run the fuel pump with the engine off and you might be able to hear exactly where screech comes from. This has happened to me for no apparent reason and throwing parts at it didn't help. Then the third time around it's OK.

  9. #9
    Join Date
    Dec 2009
    Location
    Connecticut
    Posts
    21,037

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    https://forums.holley.com/showthread...7668#post87668 ("Test Relay" for troubleshooting/diagnosis.)
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: Dominator MPFI & DIS, A/C, Spal dual 12" fans/3-core Frostbite aluminum radiator, Pypes dual 2.5" exhaust/X-pipe/shorty headers, 100HP progressive dry direct-port NOS, 160A 3G alternator, Optima Red battery, LenTech Strip Terminator wide-ratio AOD/2500 RPM converter, FRPP 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 tires.

  10. #10

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    I setup one of the gauges to show fuel flow. I started the truck, let it idle until the pump started to squeal and then shut it down. The entire time, the gauge never read higher than ZERO lb/hr. This is with the new pump and new 100 micron pre-filter installed. So where is the Sniper reading fuel flow?
    Last edited by Flatlander; 04-22-2019 at 07:42 PM.

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