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Low pressure fuel filter expand

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  • Low pressure fuel filter expand

    Hey everyone, I tried finding an older post but wasn't able to find anything. I have had my low pressure fuel filter expand/warped twice in the past week. I am hoping to get Honda to warranty out the recent one since it lasted less than a week. I've change the high pressure fuel filter and replaced the thermovale already. I had the empty gas tank/ blinking light issue over the winter. So the car didn't run for a few months. Has anyone experience what might cause the low pressure fuel filter to fail? 16230-PMS-A04 replacement filter.

  • #2
    I assume this is an 01-05? Check your pressure regulator.


    • #3
      Earlier this year, the tank valve on my 2001 would not open during key-on start. It turned out that the can portion of the low pressure filter was missing and the car was detecting a fuel line fault - preventing the tank valve from opening. When replaced, the new filter also failed due to over pressure. When the pressure regulator (swap from a parts car) was replaced, system again worked fine.


      • #4
        I had the same problems in the past. The long story short is your high pressure regulator is not sealing 100% and is over pressuring the low pressure side. Mine actually blew the low pressure filter into several pieces. You can test this by putting a pressure gauge on the high pressure regulator to see the pressure on the low pressure side (there is a plug in the side of the high pressure regulator to accommodate this). I pulled out the plug and had a hose made up with a pressure gauge (300 pis) on the end of it. The pressure should not go over 193 psi as indicated on the low pressure regulator (beside the valve cover). Mine runs at 75psi.

        My problems started with the blinking gas light with the fuel gauge on empty at very cold temps (-20F). I was told the same as you were that the solenoid in the tank had failed. I took it apart to find it was working. I put it back together only to have the problem crop up again. I could usually reset the flashing light by taking the battery cable off the battery. That worked to get me by for a while but then would not work anymore. I found through lots of work and research that there is some wires that plug into the high pressure regulator and that if I unplugged it and ran a jumper wire between the two wires that the gas light would reset and the car would run again (bad idea) and would not set off the blinking gas light. I drove the car like this for quite a while until one day I was at home and heard a loud bang late at night. I went out side to investigate, but could not find out what it was, at least until the next morning. When I went out to start my car, it started for a couple of seconds and died, and then I could smell strong natural gas. I got out and opened the hood and looked under the car to find the remnants of my low pressure filter on the ground (snow) under the car.

        The way I believe the car works is when you turn on the car it opens the solenoid in the tank to allow gas to flow for the engine to run. If at any time the gas pressure on the low side of the high pressure regulator gets excessive, the gas light will start blinking, the gas gauge goes to empty. The car will continue to run though. When you shut the car off and try to restart, the car it will not start. The computer will not open the solenoid in the tank as there is a over pressurization problem (as it shouldn't). If the pressure is lowered to normal or lower on the low pressure side (it often will as the car will consume the gas as it is running) you will be able to reset the blinking gas light by disconnecting the battery for a period of time and the car will run again. If the high pressure regulator is leaking very much, the engine may not be able to consume it fast enough and the pressure will remain high after the engine is shut off and therefore you will not be able to reset the gas light. If you release the pressure on the low side (loosen a fuel line on the low side) you should be able to reset the gas light. The sensor on the high pressure regulator is a pressure switch. If the pressure gets to high on the low pressure side, it will have the computer set off the blinking gas light. The sensor (pressure switch) is normally closed at normal pressure. At too high of a pressure on the low side it will make no connection between the two wires. DO NOT BYPASS THIS SAFETY DEVISE!!! The high pressure in a cng system is like a loaded gun. Treat it like a loaded gun as it will go off!!!! The fix is to repair or replace the high pressure regulator.

        I think the blinking gas light is misdiagnosed most of the time as a defective fuel tank solenoid. When the pressure is to high in the low pressure side, the computer will not open the tank solenoid. When the mechanic goes to replace the tank solenoid valve, he will depressurize the whole fuel system so when he puts in the new tank (they do not sell the tank solenoid valve by its self), the car will run again. It is fixed right? Not. the owner will likely be back with the same problem only to end up having the high pressure regulator replaced also. They must have both went bad at the same time right? The factory repair manual really does send the mechanic down the road to suspect that the solenoid is defective. If you study the whole factory manual supplement you will see how the car operates but it is not written to tell you why or how the blinking light gets set off. Maybe in an effort to keep people from trying to bypass the safety devise?

        I hope this is helpful.




        • #5
          Thanks Art for the detailed description of what can happen when a CNG pressure regulator begins to fail on the Civic!


          • #6
            Originally posted by agodin View Post
            I had the same problems in the past...
            Art, thanks for explaining this. I'm familiar with cars but the CNG fuel system is all new to me. I just bought a 2007 Civic GX, had the engine replaced (long story) and now it won't start. Gauge says it's empty. I know there's gas in it. And it ran with the old engine. So I'm trying to figure out with broke or went wrong when the mechanic changed the engine. He's new to CNG as well.