AEM High-Flow Low-Current Water/Methanol Injection Solenoid (30-3326)

It works perfectly and easy to wire. Polarity of the wires didn't matter

I'd like to start off by saying the product description is not very helpful, even the description directly on the AEM website isn't helpful. Don't worry though I gotchu homie. If you're using this as an addition to the AEM v2 or v3 Methanol Injection Kit then it operates as follows. The solenoid is used to prevent the injector from slowly drooling into your intake when the system is not operating. The solenoid closes and stays closed when you shut the system off. When you turn the system on it receives switched ignition power BUT the solenoid will remain closed. The solenoid will only open at whatever point you have the system set to start spraying/injecting. In other words it operates at nearly the same time as the pump and will only release fluid when the pump is pushing fluid. To dumb it down even further it only opens when they system sprays. It makes quite a nice click when it operates as well, it's loud enough to hear even if you've mounted it under the dashboard. It's pretty cool it helps you hear when you're spraying rather than guessing or looking for the little LED to start lighting up. It's also got an arrow for direction of flow so you don't have to guess. Very satisfied for the price.

Works perfectly and no pressure loss to old school check valves or sucking fluid during shutdown when vacuum is at its highest. Just set it for activation off pump controller or Hobbs switch or if you can program it like in a holley system set it to close just before pump stops to avoid fluid in intake after closing throttle which can cause misfires or in extreme cases thermal shock to pistons.