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Thread: Sniper 4150 current draw without fuel pump?

  1. #1

    Default Sniper 4150 current draw without fuel pump?

    I'm curious if anyone can confirm the current draw of the Sniper system without the fuel pump? I'm in the middle of installing the Sniper system and wiring up my vehicle with a Painless 28 circuit harness. The harness already comes with a fuel pump circuit that I was initially planning on using unmodified and eliminating the Sniper relay. My new plan is to cut the wire heading to the rear of the vehicle and connect it to the ground trigger of the Sniper harness for use as a trigger wire for a rear mounted relay (since my battery is in the trunk this would be easier). If that approach is taken, I'll no longer have the fuel pump draw on the Sniper harness. Is it safe to assume the total system draw (Sniper plus HyperSpark) without the pump would be fine on a 15A circuit, since Holley states a 15A max fuel pump and the inline fuse is 30A? If that's the case, I could repurpose the fuse block side of the harness fuel pump circuit as the power wire for the Sniper system as that is 15A.

  2. #2

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    The main power supply for the Sniper needs to connect straight to the battery and not to a fuse block. A 15 amp inline fuse is probably OK but you need to run the large red and black wires all the way to the battery. Even though the fuse block will have full voltage, it will also contain noise from all equipment hooked up to the fuse block. They only way to minimize noise is straight to the battery. For the direct wiring, if you need to extend the wire length of the red or black wires I would use the same wire gauge - even though you are no longer powering the pump through the Sniper relay.

    I think if you look at the wiring, another option for your pump would be to use the relay trigger ground from the Sniper rather than the big blue pump wire. Either should work, however.

  3. #3

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    What you want to do should work okay, but just beware of potential noise issues. Try it and if you have weird problems with the Sniper, then you'll need to extend the red & black wires back to the battery.

  4. #4

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    Thanks for the responses! I'm essentially trying not to run a multitude of positive wires back to the battery in the trunk. Would something like a noise capacitor (MSD) placed inline between the Sniper EFI system and the fuse block reduce potential issues? I do plan to run a ground wire up to a terminal behind the dash for clean ground source.

  5. #5

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    Over time I've learned that you only have to wire something once the right way to get the best results. Ground lugs on the frame and wiring into the fuse box are not recommended by Holley. That doesn't mean they won't work, but if you have problems you'll have to wire it correctly anyway. I'm in the camp of following the directions. There have been a few threads on this site that I've followed since joining related to main wiring and nearly all issues were solved when the wires were run all the way to the battery - front or rear.

  6. #6

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    Zack, not sure I'm clear which wiring you're trying to not run to the back of the car? You are still going to run the Sniper main positive & negative directly to the battery right? Are you just trying to eliminate the blue fuel pump wire from running from the Sniper to the pump?
    69 Camaro
    400 SBC, ProCharger D1SC
    1.302 60', 5.95@116.4 on pump gas

  7. #7

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    You don't need to run multiple positive wires back to the trunk. You do need to have a very good, low impedance path to the battery for your electrical draws. You can run one heavy wire (maybe 6AWG or 4AWG) from the battery up to a distribution block on the firewall and then tie the Sniper and ignition box and other things to it. The Sniper kit is designed to fit a car with a battery under the hood. When you move the battery to the trunk you have to reengineer some of the parts.

  8. #8

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    I'm essentially trying to trim down the bulky Sniper harness and use circuits already existing in my Painless wiring harness. The Painless harness already has a fuel pump lead running the length of the vehicle. I do plan to have an inertia switch inline as well, so I'm just trying to figure out the best and cleanest way to route things without duplicating circuits and having relays placed all over the vehicle.

    The issue is I do not have enough room in my sill plate passage (1970 Mustang) for a larger gauge wire such as a 6/4 AWG. I have a 2 AWG wire running from the starter solenoid (also mounted in the trunk), so I'm limited on the gauge wire I can include in the same passage. I'm also trying to keep high power lines separate from the main harness (harness on drivers side, power on passenger side).

    With all that said, that's why I was curious on the current draw of the Sniper system without the fuel pump. The smaller the gauge the better for any additional leads I need to run to the trunk if I could not tap off of an existing circuit in the Painless harness.

  9. #9

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    If you're having that much trouble packaging the wiring, then you might want to rethink the reason for having the battery in the trunk. On the last car I built I put a half size AGM battery under the hood just to avoid all the hassle of wiring a street car with a battery in the trunk. Putting a small half size battery under the hood solved a lot of issues on that project.

  10. #10

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    Easier said then done. I'm rewiring the vehicle from a previous setup so the battery and starter solenoid were already in the trunk. The area in the engine bay where the battery went is being used for other components. A trunk mounted battery isn’t bad until you have things like the Sniper system that seem to be extremely sensitive to noise and want direct to battery connections.

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