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Thread: TFI ignition breakup with electric fan on.

  1. #1

    Default TFI ignition breakup with electric fan on.

    Installed the Holley Terminator Stealth EFI on my '70 Mustang with a TFI distributor timing. I'm having an issue where as soon as the electric fan comes on, the ignition breaks up over 2000 RPM. If I unplug the fan all is well. I have added grounds and no luck. The fan does pull a lot of amps. It's a big junkyard fan from a SUV of some sort, not really sure where else to go with this. I have used a bunch of MegaSquirt EFI systems and stock ECU type systems on LSx style engines before and never had any issues. Kind of at a loss with this. My only options are going back to a mechanical style fan or possibly some sort of mechanical distributor, but that kind of defeats the purpose of having this high end EFI system. I'm running a 3G 130 amp alternator as well, and the voltage is good. Maybe someone can shed some light on this and help me get it figured out. Thanks.
    Last edited by 70MACHONE; 02-21-2018 at 07:04 PM.

  2. #2


    Define good voltage. Especially with fans, EFI, headlights, wipers, heater on low. Is the alternator mounted high, low, or mid? If the fan's motor has a metal case that's nut & bolted together, you should try grounding the case. Note: Make sure the case ground and the power ground are the same, and don't put the two external grounds together. The case ground is what's called a "non-current carrying ground". Also known as a shield ground.

  3. #3
    Join Date
    Dec 2009


    Many years ago (when I first started with EFI), I had a similar problem with my Spal dual electric fans. I solved the problem with better overall grounding (LINK), heavier gauge electric fan wiring, a 75 amp relay (LINK) and upgrading to a Ford 3G alternator. The voltage is probably dropping too low when the fans turn on. This is usually caused by poor grounding (LINK), or insufficient size wire (AWG) powering the electric fans. Also, look at where the live cursor moves to during this occurrence, and tune that area of the Base Fuel Table.
    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.

  4. #4


    I called Holley support, I explained my situation & wiring setup, and there recommendation was check the volts with the fan running at the red/white switched power wire, since that controls the distributor power.

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