When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
I am rewiring my factory fuel level sender to my fueltech standalone and noticed both of these "2 way" valves have been removed at some point. My question is are they really "2 way" check valves? $160 for 2 is crazy! Part # GA5R-42-910
What is their purpose? The 1 Way check valve by engine prevents boost pressuring of the system and the rollover valve on top of tank stops large amounts of fluids coming up the lines so what do these do?
Under thread REPLACING ONE WAY VALVES ON GAS TANK there is someone who claimed they are not as simple as just 1 way check valves back in 2023
But on REVLIMITER.NET there is a thread showing how to clean gas tank valves on a 1990 Miata with the same valves to help with gas smells and he describes it as acting just like PCV valve (Picture Attached)
Lastly if I am not connecting the fuel tank evap line to the engine due to engine swap would I even need check valves? (Depending Function Of Valves Obviously)
The 2 way valves connect to the right rollover valve directly to the aft vent box and then the charcoal canister. The right rollover valve connects to the vent box aft of the fuel pump. The 2 way valves prevent too much vacuum and pressure in the fuel tank.
So what I am assuming then is the valve allows air to flow both directions if blown through gently but will shut and restrict air flow in both directions if blown into with more velocity and volume (air flow)??
I don’t think so. When I blew them each way they stayed open. Only restriction was the diameter of the pipe. When I was testing I was trying to figure out why my tank was building so much pressure (more than what these valves were supposed to hold). In my case everything tested correctly but still had high pressure issues. The problem seemed to resolve when i filled the tank (before it was a 1/2 tank with older winter gas). Not 100% sure but I am thinking the winter fuel was vaporizing faster than the valves and charcoal canister could dissipate (hot fuel entering the tank from the return).
