[JMD]

Hi all,
I have Dakota Digital's VHX gauges in my '68 k10. The speedometer gets its signal from a transfer case mounted vehicle speed sensor which is also made by Dakota Digital. Everything has been working great for the past 3 years, that is until I ditched the carb and installed a Holley Sniper EFI system.
Now as soon as the truck starts moving, the speedometer jumps all over the place. Sometimes I'll be barely moving and the speedo will jump straight to 100mph. While not having an accurate speed reading is annoying, I'm more concerned that it's more than tripling the miles that should be reading on the odometer.
I know I'm getting electromagnetic interference somewhere in the VSS circuit. I verified this by bringing the truck up to speed, putting it in neutral and turning the ignition off. As soon as the engine and fuel pump stop running, the speedometer reads normally.
So my question is, what part of the Dakota Digital VSS circuit is most susceptible to EMI? The VSS wire is running parallel with the fuel pump power wire, but I made sure to keep them at least 10" apart down the length of the frame. Is that not enough separation? The only other trouble spot I can think of would be interference from the Holley ignition system getting to the brains of the Dakota Digital control box. But again, all ignition wires are at least 10" from the control box. I'm at a loss here, any suggestions?