05 V8 won't start when hot

Lincoln LS

  1. alexlstc

    alexlstc New LVC Member

    Messages:
    2
    Likes Received:
    0
    Joined:
    Mar 11, 2019
    Location:
    Ontario, Canada
    Hi everyone. I'm having an issue with my LS that's driving me insane. Before I start throwing more parts/money at it, I was hoping someone here might have an idea or have seen something similar before.

    My LS will start perfectly when it's cool, but not when hot. I can start it up and drive it somewhere, but when I park it and turn it off, I cannot start the car until it cools down again. It cranks, but won't start. The car runs flawlessly otherwise, with no roughness, no hesitation, and fuel economy is good as it's always been. No check engine light and no codes are thrown.

    I have searched the forum and Google, but haven't found anything that describes the problem perfectly or that I haven't tried yet. If you know of another thread, please link me to it and accept my apologies.

    Details on the car: 2005 Lincoln LS V8 Sport. 230,000 km (140,000 miles). Bone stock. I have owned this car for 10 years and around 100,000 miles, but it was stored for around 4 years as I was having medical issues and couldn't drive.

    I am currently driving on the valet key (lol) as my mother threw away both sets of keys while it was sitting in her garage during a cleaning purge, thinking they were my grandfather's old keys. Not sure if relevant.

    This issue started after I put it back on the road two years ago, but it was intermittent and the car would start after sitting about 3-5 minutes. It is now constant and the car needs 30-45 minutes before it will start up again.

    Battery was replaced after putting the car back on the road, and is in good shape. I tried swapping in one from my other car anyway and the issue was not fixed.

    I replaced the cam and crank position sensors, as I've had issues with failing sensors becoming heat soaked with Fords in the past. This did not fix the issue. (Once I found the crank sensor, I felt foolish to think this was getting heat, but did it anyway since I had the replacement.)

    I then borrowed a friend's scanning tool which does live data and noticed that when it's having trouble cranking, the fuel pressure was quite low (~18 psi). When it starts, it was in the 40-50 range. I replaced the primary fuel pump (pass. side) and now have a consistent 58-60 psi fuel pressure on startup. But the issue persists.

    I got a better scanner and collected more data while driving. Coolant temps are a little high but not that much (car idles around 205-210 degrees, reaches 215-220 at WOT but quickly settles down to 205). It might be due for a cooling system overhaul soon but I don't think this would cause the no-start issue.

    What's interesting is that the issue doesn't seem to be correlated to the coolant temperature. Even after the coolant comes up to normal running temperature, the car will still start again as long as it hasn't been running longer than 10 minutes or so.

    So I am at a bit of a loss here, and I'm hoping someone might have seen this in the past or have an idea where to look next. I'm not opposed to buying parts to try things out, but I'd rather not throw a lot more money at it grasping at straws. I still have the scanner and I can go collect any other requested information.

    Thanks in advance and sorry for the long post. I just wanted to make sure I gave you enough information to work with.
     
  2. joegr

    joegr Dedicated LVC Member

    Messages:
    19,514
    Likes Received:
    1,417
    Joined:
    Dec 10, 2005
    Location:
    Gulfport
    When it won't start: Have you checked to see if the coils are firing? Are the injectors pulsing? Have you tried clear flood mode?
     
    Last edited: Mar 11, 2019
    • Like Like x 1
    • 04_Sport_LS

      04_Sport_LS Dedicated LVC Member

      Messages:
      2,718
      Likes Received:
      278
      Joined:
      Jun 12, 2012
      Location:
      Somewhere around Lake Erie
      And... Has the fuel filter ever been replaced since you have owned it??? If the fuel pump is trying to push fuel through an exteremely dirty filter... It will get hot and overheat the relay.

      Fuel filter is a $10 part... And takes less than a half hour to change.
       
      • Agree Agree x 1
      • Elessee

        Elessee Well-Known LVC Member

        Messages:
        312
        Likes Received:
        2
        Joined:
        May 19, 2007
        Location:
        Modesto
        "...when it's having trouble cranking,..."
        Trouble? Are you saying it is slow cranking when hot? Slow cranking is from a lack of battery juice to the starter motor.
        I had this problem on my 88 LSC. The cure is to run more grounding straps to the engine block. Rather than a proper strap, I ran one, short battery cable directly from the alternator to the fender, using existing bolt heads. That cured it.
         
      • kgtorino

        kgtorino LVC Member

        Messages:
        16
        Likes Received:
        3
        Joined:
        Feb 7, 2018
        Location:
        Sarasota Florida
        Alexlstc......Ive got the identical problem. Mine is a 06 LS. Still unresolved. I've changed fuel pump, fuel pressure relay, checked all fuses and relays. It's just been sitting in my driveway like a pretty Boat anchor. Starts and runs great cold.... after only 5 or so minutes running, will not restart for quite a while. I will link my post if I can find it. I've ordered a replacement ECM. I don't know what else to do. I'm not to savvy about linking posts, but it's called " No hot start until after cool-down?".....I've been waiting for so long for someone who's had the same issue , I thought I was crazy . Best of luck to you on resolving yours.
        No Hot Start, until cool down?
         
        Last edited: Mar 13, 2019
      • alexlstc

        alexlstc New LVC Member

        Messages:
        2
        Likes Received:
        0
        Joined:
        Mar 11, 2019
        Location:
        Ontario, Canada
        Hi everyone, thanks for your responses, and sorry it took me a while to update the post. Work has been heavy and the weather's been bad.

        Fuel system is working fine. I've got full pressure at the rails and the injectors seem to be okay. Clear flood didn't help.

        I picked up a spark test tool and tried this a few times. When I try to start it hot, I have no spark. As soon as it cools down, I get spark again. The coils and plugs are fine and were done not too long ago, all Motorcraft OEM.

        I don't see any issues with the wiring or the connections, so I'm starting to suspect that it could be an issue with the PCM. It's the only thing we haven't eliminated yet.

        I hope I'm wrong, but running out of other ideas...
         
      • AmsterDutch

        AmsterDutch Dedicated LVC Member

        Messages:
        1,331
        Likes Received:
        225
        Joined:
        Jul 9, 2017
        Location:
        Midwest
        Are you 100% sure the
        cylinder head temperature sensor
        working properly? Maybe and a big maybe it could be the Temperature sensor is forcing a Rich start because the sensor thinks the engine s too hot...just a thought ...and yes I know you said the temp was 205-225 but it’s something to check out before a PCM Reflash/ Reprogram
         
      • joegr

        joegr Dedicated LVC Member

        Messages:
        19,514
        Likes Received:
        1,417
        Joined:
        Dec 10, 2005
        Location:
        Gulfport
        May I remind you of what he said?

        While the PCM injects less fuel for a hot start than a cold start, it certainly does not cut the ignition just because of a warmer than true temperature reading.

        Also do note that if you remove the CHT sensor, you must replace it with a new one! It's a one time install for each sensor.

        I don't see why engine temperature would affect it, but relay C1003 in the trunk powers the COPs. I would swap it with another one and see if that resolves anything. Unfortunately, it's not clear to me how to identify which one (001 to 007) is actually C1003. It's not 003, that's for the rear defroster.

        If it's not the relay, then unfortunately the PCM looks like a good suspect.
         
        • Like Like x 2
        • AmsterDutch

          AmsterDutch Dedicated LVC Member

          Messages:
          1,331
          Likes Received:
          225
          Joined:
          Jul 9, 2017
          Location:
          Midwest
          Yes I agree the car will not cut off the ignition totally just thought maybe it would drench it with fuel ....but if the Spark plugs don’t smell like gas then it wouldn’t be a overheating issue.... I suppose A bad crankshaft position (CKP) sensor might have broken, loose or corroded wires from the sensor to the PCM. But that wouldn’t explain why it starts fine when it’s cold would it?
           
        • AmsterDutch

          AmsterDutch Dedicated LVC Member

          Messages:
          1,331
          Likes Received:
          225
          Joined:
          Jul 9, 2017
          Location:
          Midwest
          If you still have the scanner can you get some info on the O2 sensors?
           
        • joegr

          joegr Dedicated LVC Member

          Messages:
          19,514
          Likes Received:
          1,417
          Joined:
          Dec 10, 2005
          Location:
          Gulfport
          He says he replaced the cam sensors and the crankshaft sensor. I think he's covered the normal suspects.
           

        Share This Page

        1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
          By continuing to use this site, you are consenting to our use of cookies.