PCM - PCM RELAY PROBLEM ?? | FordForumsOnline.com
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PCM - PCM RELAY PROBLEM ??

Discussion in 'Ford Crown Victoria' started by Oriley, Jan 21, 2018.

  1. Oriley

    Oriley New Member

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    Location:
    Northern MN
    1998 Crown Vic LX
    36,900 miles
    Bought 12-19-17

    Bought this at auction, car was in garage ~3 years. It has a battery maintainer, radio presets still set so I think it has had power all this time, battery is still strong.

    Car was towed here then I had it running maybe 2 hours checking things out, purrs like a kitten. When I went to restart it still hot when the keys was on "on" the radio blared, lights blinked and heater came on - all this for maybe 5 seconds then it wouldn't start. Cranks fine but no start. Since then I have started it a dozen+ times and it fires right up.

    Yesterday I had it running maybe an hour and when I put it in gear to drive in I noticed the doors didn't lock like they usually do. Hmmm - shut it off and when I move the key to "on" the heater blower came on for ~5 seconds then shuts off, cranks but wouldn't start again. Today it started just fine.

    I'm lost. I bought a cheap Actron CP9125 reader and it shows "0 Codes" and the check engine light does go out after starting it.

    Another gent suggested getting some electrical cleaner and look at the relays under the hood, I'll do that tomorrow.

    Beautiful car and everything works fine except for this occasional electrical gremlin. I can't drive it just yet, no title or license (long story) but I'd love to fix this.

    Thanks very much for any suggestions.
  2. Action

    Action Moderator Staff Member Respected Member

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    Welcome to the FFO!

    You want to isolate the issue. Either fuel or spark. When the issue is presented, turn off all sound makers and listen for the fuel pump. And test for fuel pressure at the fuel rail.

    Or every time you start the engine, turn key to just the on position and listen with everything off. Then crank engine.

    Intermittent concerns are one of the hardest to diagnose.

    >>>>>>>>Action
  3. Oriley

    Oriley New Member

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    Thanks for the welcome. :)

    When this happens it almost starts, so it's firing, then it just turns over. I'll listen for the fuel pump next time.

    Before I turn a vehicle off I always turn off the accessories first so that is why I wonder when this happens they come on for ~5 seconds.

    I'll have to look into checking the fuel pressure, maybe buy new toys for that?

    I already bought a new battery so I'll throw that in then take a peek at the relays under the hood.

    Thanks again.
    Action likes this.
  4. Oriley

    Oriley New Member

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    With the warmer weather it died for the first time idling in the garage, wouldn't restart. I still haven't driven the car till I figure this out.

    Next morning it starts - 32# at fuel rail - runs for 40 minutes - fuel pressure drops to 0 - engine dies - second later fuel relay goes to 0 volts.

    Yesterday I ran it (one minute) out of the garage, couple hours later it wouldn't start, next morning starts fine. Half the people tell me fuel pump, half say a hot module, I don't know.

    Any ideas now? This one has the coil-on-plug, no distributor.

    Thanks
    Last edited: May 8, 2018
  5. Dominick 1

    Dominick 1 Well-Known Member Respected Member

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    Many of those had issues with water get in the front frame rails and giving issues
  6. Oriley

    Oriley New Member

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    I have no idea what that is but I'll look it up, thanks.

    I live in a remote half-horse town but we do have a decent garage next town over, will their computer tell them what it is and I can quit all this guessing?
  7. Dominick 1

    Dominick 1 Well-Known Member Respected Member

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    I kind of doubt it
    A mechanic I worked with for years had the same problem on a Merc Maurader
    It just is a hunt job
    The water gets inside the frame rails where the wiring is located and shorts out
    I suppose you could use a test lamp to try to find the short
    That's not a good answer.
    But that is all I can think of
    It is a bad design
  8. Action

    Action Moderator Staff Member Respected Member

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    The fuel pressure you posted 32 pounds is too low.
    The pressure should be over 35 to 38 pounds and 40 or a little higher would be what I would have expected for a healthy system.

    EZ would be fuel filter

    Pressure regulator and pumps would be other areas to look at for low pressure.

    Zero is another matter

    >>>>>>>Action
  9. Oriley

    Oriley New Member

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    Had it towed to my nephew's shop last fall, it was the fuel pump and something else I can't remember... something on the pump?

    Runs like a top, just turned 37k miles. :)

    Thanks guys.
  10. Action

    Action Moderator Staff Member Respected Member

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    Thanks for posting back with the result.

    >>>>>>>>>>>Action

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