FUELAB Tech Tips: Where is the Best Place to Use a Check Valve?

A check valve can have many functions: hold rail pressure, shorten the pump priming time, and help with hot starts. In this article we take a deeper look at how they can benefit your engine.

A check valve can have many functions: hold rail pressure, shorten the pump priming time, and help with hot starts. Emissions are more important than ever these days as well. Holding rail pressure while the engine is cooling, prevents the fuel from boiling off, thus cutting back on evaporative emissions. The EPA is all over the motorsports industry these days, so its up to all of us to do our part.

Just as important as the valve itself, is its placement – at least as it pertains to overall system performance. For some reason many folks think the check valve should be placed before the pump. While that would still achieve the overall goal of holding rail pressure, it’s putting unneeded stress on the fuel pump when it’s running, eventually leading to pump damage. A fuel pump is just that – a PUMP. They are meant to push fuel, not pull it. When there’s a check valve on the inlet side of the pump, it’s creating a restriction. The more inlet restriction you have, the louder your pump is going to be and the hotter it’s going to run. Enough inlet restriction leads to pump cavitation, which damages the wear plates, rotor, vanes, and pump housing, ultimately causing the pump to no longer build adequate pressure. This is true of any pump from any manufacturer. It’s just good practice to reduce the inlet restriction as much as possible when designing and installing your fuel system. With that said, having a check valve in your fuel system is almost always a good idea, just be sure you have it on the pressure side of things. 

We make it easy to incorporate a check valve into your layout. Our 848 and 858 Series filters have a check valve integrated into the outlet side of the filter. If you already have a standard filter (ours or a competing brand), no problem! We also offer the 717 Series stand alone check valves in your choice of -6AN, -8AN, or -10AN configurations.