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Thread: HyperFuel G-Surge fed by mechanical pump.

  1. #1

    Default HyperFuel G-Surge fed by mechanical pump.

    I've searched several days and don't find a similar situation. I've been fighting with a pulsating fuel pressure issue (pulses from 60-70 psi at idle) since I got my truck operational.
    My fuel system setup is a bit more complicated than some since I have dual tanks. I have the original mechanical fuel pump and supply lines running to a HyperFuel G-Surge tank. I then have a separate return line (3/8" aluminum tubing) from the surge tank back to the main tanks going through a 6-port switch valve.
    After some troubleshooting I discovered that the mechanical pump was pre-pressurizing the surge tank and the pressure pulsation was the result of each time the mechanical pump arm was stroked by the cam lobe. (If I remove sniper return line and run into a Jerry-can, fuel pressure runs a steady 62 psi). The biggest contributor is obviously backpressure in the low-pressure return line which I tried to reduce but it didn't help enough. I'm restricted by the switch valve port size. I then tried a low pressure regulator (Holley 12-804) on the low-pressure supply line into the surge tank which smoothed out pressure at idle when turned all the way down, but starved the surge tank at cruise. (Truck would run out of fuel and stall on the highway.)
    My questions:
    Is there anyone else out there running a similar setup with original mechanical pump with a pulsation issue?
    Is the Sniper fuel pressure regulator not able to adjust quickly enough to these pulsations?
    At this point it appears my only remaining options are A: External high-pressure regulator on Sniper pressure line or B: Electric low-pressure pump for more consistent supply to the surge tank. Any additional suggestions are welcome! Thanks!

  2. #2

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    I have the G-Surge unit as well. I'm feeding it with a Holley Blue pump. My unit fluctuates as rapidly as the injectors cycle. Haven't quite figured why. I suspect that because I'm not running a return, the injector pulses are not dampened and this is transmitting directly to the fuel pressure gauge because once the engine is off, pressure is smooth. I'm running hard lines and a steel braided line to the Sniper.

  3. #3

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    Quote Originally Posted by Gen2Van View Post
    I suspect that because I'm not running a return, the injector pulses are not dampened and this is transmitting directly to the fuel pressure gauge because once the engine is off, pressure is smooth.
    So during the prime cycle, your low pressure electric lift pump runs simultaneously with your HyperFuel G-Surge and produces a pretty smooth/even pressure? I assume the Holley Blue pump runs smoothly/consisntently (at least compared to a mechanical engine driven pump)?

  4. #4

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    Yes. When the engine is off, fuel pressures are smooth. The G-Surge unit I have is plumbed to return to the tank through a 3/8th line, so the low pressure fuel pump only produced enough pressure in proportion to the amount of restriction it takes to push the fuel through the return line. I would surmise that with a mechanical pump, the flow rate would be far less then a Holley Blue and if the G-Surge return line is big enough, this shouldn't cause a pressure fluctuation. You could put a fuel pressure regulator on the low pressure output to the G-Surge and set it to 3 psi. This would limit the max pressure of the mechanical pump. If your G-Surge output still fluctuates, the problem wouldn't be related to the feed pump.

  5. #5
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    A long time ago on my first EFI conversion, I installed one of these surge tank/low pressure pump things. It was nothing but trouble. I never used one again. I've found it's more important to mount the fuel pump close to the pickup tube (even at the top of the fuel tank), and keep the suction line as short as possible. I never had a problem since with one high pressure EFI pump.
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  6. #6

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    Yeah, on my first conversion many years ago, I ran an in-tank pump (preferred setup) and it worked beautifully! I've had inline pumps as you describe, that worked just fine too. However, on this one, I figured the surge tank would be the simplest and most reliable way to utilize both of my unbaffled tanks (it's a 4x4 work truck that sees some rough terrain). I had a buddy several years ago that made his own surge tank (they weren't commercially available at the time) for a dual tank setup on a GM TBI retrofit and it worked pretty well (he still uses it). But then I think he ran an electric low pressure feed pump to the surge tank. On mine, the pressure really only pulsates at idle and smooths out to 62 psi at 1200 RPM & up. I may try a low pressure electric feed pump I have laying around to see if pressure is more consistent at idle. If not, I suppose I may just have to live with it since it really only pulsates at idle...unless I want to spend a lot more money and time on it! I really appreciate the input guys!

  7. #7

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    Hey Plowboy, any updates on what you did to correct the issue? I'm setting a system up on my 1982 Ford E250 with dual tanks.

  8. #8

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    I use the G-Surge with return line also. Initially fed with Holley Blue and now, to reduce noise, a small low pressure Holley pump. No issues with either, but then my return line is the same size as my feed. A little, cheap, quite electric pusher might be all you need to feed the surge tank.

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