My rig has a 7.4L Chevy engine with a Rochester 4 barrel carb - no fancy emissions stuff. I just built my kit from HybridWaterPower and installed it. I haven't measured the output of the power cell yet, but it's drawing right at 20 amps. Problem on the first run was that the engine at idle sucked all the water out of the bubbler before I knew what was happening. The suggested fix was to drill a hole in the pressure relief valve (rubber cork) to satisfy the vacuum. Didn't have much effect. Drilled a bigger hole (1/8"), no effect. Have built a taller bubbler to hold more scrubbies and have installed a solenoid-operated shutoff on the vacuum line to the engine intake port (tapped into the pcv line).
Has anyone had a similar problem? Can you recommend a fix?