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Thread: Keyed Power/Relay Question

  1. #11


    I've installed a lot of Snipers and have never used a relay for the pink wires, but I don't see why it wouldn't be a good solution for certain applications. A worn ignition switch could create some funky behavior with a Sniper. In a nutshell, digital systems operate very, very differently than analog systems and most hot rod guys don't know how to debug digital systems. Very few hot rod guys have digital backgrounds so they lack the knowledge to debug digital problems and Holley didn't do anyone any favors when they wrote the instructions. Holley should've added a couple of pages on potential digital issues such as interrupted power, power glitches, power surges, RFI noise, etc. 5 volt digital circuits are very sensitive to a bunch of things that analog ignition systems simply shrug off.

  2. #12


    Holley should have done two things that I think would have made their life and the lives of Sniper users much better. First, they should've separated the ECU B+ feed from the fuel pump B+ feed - two different circuits. With this configuration, the voltage drop caused by the fuel pump startup current won't be seen by the ECU, and they should have included a trigger ("pink lead") relay fed by the ECU only power feed to eliminate that above mentioned issues. I'm sure they didn't because of cost issues, but what's the cost in the long run? I immediately changed my Sniper install to this arrangement and EMI/RFI/ECU resets have never been an issue. For me this was especially important because I was dealing with 40 year old British electrical systems (Lucas, Prince of Darkness).

  3. #13
    Join Date
    Dec 2009


    Must be a Sniper EFI thing. I've never had to use a relay on the switched (keyed) +12V red/white wire with the HP/Dominator EFI systems. From a '78 Ford Bronco, '92 Ford Mustang, to a newer model Ford Mustang, never a problem.
    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, Holley Dominator MPFI & DIS, 36-1 crank trigger, 1x cam sync, 200A 3G alternator, Optima Red battery, 100HP progressive dry direct-port NOS, R134a A/C, Spal dual 12" fans, Frostbite 3-core aluminum radiator, Pypes dual 2.5" exhaust, off-road X-pipe, shorty headers, -6AN fuel system plumbing, Walbro 255 LPH in-tank pump & Pro-M -6AN hanger, S&W subframe connectors, BMR upper & lower torque box reinforcements, LenTech Strip Terminator wide-ratio AOD, 3000 RPM converter, B&M Hammer shifter, Stifflers trans crossmember & driveshaft safety loop, 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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