Review on 🔥 Holley (12427) Fuel Pump: Reliable Performance for Optimal Fuel Delivery by Joel Wright

First, yes, it's a "pass-through" pump, and it lets fuel through when it's off. I use it to fill up my carbs after my truck has been sitting for over 2 days. I have it with a momentary push button switch and I run it for 3-5 seconds then I crank it and my mechanical pump kicks in from that point. It works (although I only run it for a few seconds at a time) for months - still going strong.