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Evap System 93 EX F22A6

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    Evap System 93 EX F22A6

    Hello im lucas from argentina. I am doing some repairs in my Accord and i want to know how exactly works the two way valve. All the process. I have the problem that pressure builds up in the fuel tank after driving for a while. I know beacuse when i open the gas cap, i hear pressure hissing out. Maybe is the Evap system at front of the car.. I will check that later.. First i want be sure that the two way valve is working correctly since i lowered the fuel tank. I cant find how to test this in the manual.

    In picture the fuel tank is empty and the valve number 1 is open. I tried it. Shouldn't it be the other way around? I mean, maybe the valve 1 should be closed and when pressure builds up, it open. Should open at a certain pressure to let gas flow to valve 2. Is that so?

    Valve number 2 i have no idea how it works.

    After driving a while the check engine light is on. Diagnostic says Fuel Supply System. Could it be because of the evap system?

    Can you tell me how to test the two-way valve?

    I appreciate all the information


    Attached Files

    Lucas welcome to the forum. I think your the first person from Argentina on the forum! That is normal for the tank to hiss when you take the fuel cap off, especially after driving. Which code is it throwing? Also is the car acting weird?
    FSAE (F Series Accord Enthusiasts) ..."A dying breed thats taking it to the next level" Lucky #13
    MR Thread:


      Thank you grumpys! The code is 43 and yes, when i accelerate the car at low rpm, it makes a slight jerk, like lack of fuel it seems to me. Baybe is the pump or the pressure regulator in the inyector rail. I have to try ir yet. At this time, i would like to know how two way valve works and be able to test it and make sure everything works fine before assembling. Also want to educate myself!

      Thanks for answering!!


        ok!any information? nobody? somewhere I can find?


          Vent #2 in your picture is a fuel tank pressure control valve, to prevent over pressurization of the fuel tank, it vents to the charcoal canister. The evap system builds pressure in the fuel tank while the vehicle is in operation to check for leaks, so when you stop to fuel up, hearing a hiss is normal as it vents all of that pressure out. Code 43 is a fuel related code and can be time consuming to diagnose. If you have can, test the fuel pressure at the rail. At idle the pressure should be ~30 or more PSI. If it is less than that I would start with a fuel filter and test again. It could also be a faulty o2 sensor. Are you using considerably more fuel than you are used to?

          Edit: Correct spelling mistakes. By the way, welcome to the forum!
          Last edited by Size9zombie; 07-27-2021, 01:01 AM.
          Under Construction​​​​​​​​


            Thanks size9 for answering!! i am clear about valve #2​ now valve #1, should be normally open o closed?
            About de trouble code, i couldnt test the fuel pressure at rail for now but I was able to measure direct pressure from the pump and it gave me between 50 and 55 psi. According to the manual this would be fine. I take to clean and test the injectors, that's why I could not do the measurement on the rail. Fuel filter is new.
            Regarding fuel consumption, i was loading 13lts every 150km approx which would be 3.38 gallons every 90 miles150km 13lts 3.38galons 90millas​. its that ok??
            i will test valve #2!! thanks!


              Valve 1 on your picture is a rollover valve and is normally in an open position. Should the vehicle go upside down it seals the tank to prevent fuel from leaking out into the evap system. It sounds like you are getting about 26.6 miles to the gallon which is within a reasonable range. 50-55 psi is normal. The most common thing to cause the code you have is the o2 sensor. Pressure build up in the fuel tank is normal operation of the evap system and will not be the cause of the engine light being on.
              Under Construction​​​​​​​​


                Do you have any drivability issues? Running rough, stuttering, stalling? Or just a check engine light on.
                Under Construction​​​​​​​​


                  Excelent!!! Now i can reinstal the tank quiet. The only problem i detect sometimes is when i accelerate the car hard at low rpm, it makes a slight jerk as if there was a lack of fuel. New fuel filter, pump with good pressure, clean inyectors, new distributor, spark plugs and wires olso new. I will have to test it. When i start the car in the morning and drive less than 1 mile, the check engine light is on. If I turn off the engine and turn it on again, sometimes it starts and sometimes it doesn't. I arrived to work, turn off the engine and i leave it that way for all day. When i come home, the check light engine does not come on. The nex day is the same thing. When the light is on, the car is running normally.
                  The o2 sensor is heated? Maybe it takes time to take temperature and thats why light the check engine. Im going to consult the manual to now how test it.
                  Thanks for your help!