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1998 Crown Vic cranks but won't start/ stalls. Full tank. Ran fine

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  • 1998 Crown Vic cranks but won't start/ stalls. Full tank. Ran fine

    Hi
    Appreciate some help here.
    Car has been great- my 4th CNG CV- this one only had 35k miles on it when I bought it 10+yrs ago. Now 106k miles.
    I let it sit a couple of weeks while travelling. Came back started fine- drove around start stop no problem.

    Next day, cranked- ran a bit. Stopped. Cranks, won't restart. Fuel was full when I left and still indicates as such.
    Disconnected battery in hopes of hard reboot.
    Same- cranks- catches- dies (as if ran out of gas).
    Additional cranking doesn't even catch at all

    Fuses ok. Replaced the fuel relay (in the separate box on driver front fender.
    Jumpered 85 86 on fuel relay- no difference.
    Pulled the 30 amp cng fuse (in the box by battery)
    Seems to catch again- then die. No catch on subsequent tries- just cranks.

    Thoughts?
    I'm thinking fuel rail solenoid cutoff valve doesn't open?
    Thanks!
    Bob


  • #2
    Have you checked the fuel pressure in the rail @ the schrader valve--it should be above 100 psi. Also, there is a safety switch in the trunk in the same location as gasoline models. It triggers during a roll over or sometimes a pothole. It can be reset by reaching behind the trunk liner near the top of the LH quarter panel and pushing the plunger in if it has been triggered. Another possibility is that the fuel filter is totally plugged but probably unlikely.

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    • #3
      Originally posted by next2pool View Post
      Have you checked the fuel pressure in the rail @ the schrader valve--it should be above 100 psi. Also, there is a safety switch in the trunk in the same location as gasoline models. It triggers during a roll over or sometimes a pothole. It can be reset by reaching behind the trunk liner near the top of the LH quarter panel and pushing the plunger in if it has been triggered. Another possibility is that the fuel filter is totally plugged but probably unlikely.
      Thanks. Yes pressure to the fuel rail at schrader valve. No Gauge but from my bicycle experience- it was nearer 100 psi then 10psi.
      Good tip on inertia switch. I'll try that.

      Fuel in California- Cleanenergy/PGE is all very good and dry.

      Comment


      • #4
        Originally posted by K38Bob View Post

        Thanks. Yes pressure to the fuel rail at schrader valve. No Gauge but from my bicycle experience- it was nearer 100 psi then 10psi.
        Good tip on inertia switch. I'll try that.

        Fuel in California- Cleanenergy/PGE is all very good and dry.
        I was hopeful that it was the inertia switch- since the last time the car ran I pulled into the driveway. Due to long travel day and some jet lag and some impatience- not my smoothest parking- car rolled a bit while putting into park- possible inertia input but really not big. Doesn't seem to be triggered. Red button down in recess.
        I did then move the shift PRNDL through the gears to see if a shift interlock issue (my original thinking when I disconnected the battery- reboot the signals). No luck.
        I then pulled the under dash fuses 5 (shift interlock) and fuse #7 (Power control module- PCM).
        It seems the engine cranks and catches briefly after these power recycles. Subsequent attempts just cranks.
        Thanks!

        Comment


        • #5
          If you have pressure in the fuel rail the problem points to no spark or no fuel injector action. I'm not sure what powers the injectors. As far as spark, that's a bit difficult to check on these because of the coil over plug design. I suppose it could be a bad powertrain control module. At this point your issue could be similar to gasoline version problems like faulty crank position sensor, cam position sensor, ?? If it occasionally catches while cranking it still points more to fuel than spark. Most of those older injectors leak a bit even when they are supposed to be closed so that could explain the occasional tendency to start. To be sure I would try to find a gage to see what the actual pressure is on the fuel rail.

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          • #6
            Originally posted by next2pool View Post
            If you have pressure in the fuel rail the problem points to no spark or no fuel injector action. I'm not sure what powers the injectors. As far as spark, that's a bit difficult to check on these because of the coil over plug design. I suppose it could be a bad powertrain control module. At this point your issue could be similar to gasoline version problems like faulty crank position sensor, cam position sensor, ?? If it occasionally catches while cranking it still points more to fuel than spark. Most of those older injectors leak a bit even when they are supposed to be closed so that could explain the occasional tendency to start. To be sure I would try to find a gage to see what the actual pressure is on the fuel rail.
            Hi,
            Yup over 100 psi at schrader valve.
            This is a global on/off issue I think. I don't think all injectors or plugs would go at the same time. I did replace the coil over plugs on all plugs so I know whats that like to begin failing.
            I'm thinking its either the fuel rail cut off solenoid (power or logic or mechanical) or spark signal / logic.
            Here's the fuel rail. The schrader valve is between the tanks and fuel rail cut off. Hard to tell but the fuel sensors are downstream from cut off valve and per bank of V8.

            I really liked the inertia switch failure idea- could still be something there?
            Attached Files
            Last edited by K38Bob; 10-03-2018, 02:31 PM.

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            • #7
              I think if you have pressure in the fuel rail (while cranking by the way) the shut off solenoid and the inertia switch are not the issue. I'm still thinking the injector driver (whatever turns them on and off) or spark

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              • #8
                If it's a driver problem (injector/spark), it may be the Alt Fuel Module. If the '98 is like the 2000-2004, the Alt Fuel Module is an EEC-IV ECM that is mounted behind the grill, but in front of the radiator.
                It would be a swap and try situation. You would need to pull it, and get the info off the label next to the connector on the ECM itself. It's mounted in a black box/bracket.
                I have several, but would need to have a matching code number/software version.
                Your Friendly Nazi Squirrel Administrator

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                • #9
                  Originally posted by cnghal View Post
                  If it's a driver problem (injector/spark), it may be the Alt Fuel Module. If the '98 is like the 2000-2004, the Alt Fuel Module is an EEC-IV ECM that is mounted behind the grill, but in front of the radiator.
                  It would be a swap and try situation. You would need to pull it, and get the info off the label next to the connector on the ECM itself. It's mounted in a black box/bracket.
                  I have several, but would need to have a matching code number/software version.
                  Thanks. I've been down with a bad cold. I know about that module from a previous CV I had. All take a look.
                  Thanks
                  Bob

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                  • #10
                    Originally posted by next2pool View Post
                    I think if you have pressure in the fuel rail (while cranking by the way) the shut off solenoid and the inertia switch are not the issue. I'm still thinking the injector driver (whatever turns them on and off) or spark
                    Not sure how the fuel rail could have fuel before cranking and after cranking but not during cranking?
                    Fuel shutoff solenoid is downstream of schrader valve. So all cylinders would be affected.
                    Of course it could be signals/driver to all cylinders (fuel or spark)
                    Thanks!

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