Engins wont start after 3 hours

Discussion in 'General Maintenance/Repair Questions' started by Bill the Boater, Aug 3, 2020.

  1. Bill the Boater

    Bill the Boater New Member

    2
    Aug 3, 2020
    Sea Ray1998- 37EC
    3534 Mercruiser Horizens EFI inboards
    I have a 1998 Sea Ray 37 EC with 454 7.1 Horizons inboards.when I start engine cold they run great for hours. When I stop engine for 3-4 hours they won't stay running. backfire, no idle try everything.wait 3 more hours there cold and they start right up and run great. they will also start if started back up in 1-2 hours after running. just had plugs, wires ,cap and rotor replaced. And the real mystery is its both engines act the same. I also changed all fuel filters and running new fresh gas. Ive had 3 professional mechanics look at it and they scratch their heads,.........Please suggestions..
     
  2. joeyleggz

    joeyleggz Active Member

    636
    Jan 15, 2013
    long island
    current boat: 1997 sea ray 330 express cruiser
    twin 454's efi
    Vapor lock, try running the blowers for a while after shutdown and before startup . Happens to me on my starboard motor fuel cooler on that motor is in between the two motors.
     
  3. ColoSR

    ColoSR Active Member

    198
    Apr 25, 2018
    2003 Sea Ray Sundeck 220
    MX 6.2L MPI Mercruiser with 2.2 Bravo III drive
  4. face89

    face89 New Member

    11
    Aug 4, 2009
    Chicago, IL
    380 Sundancer 2000
    454 Mercruiser Mag MPI Horizon Gen VI Inboards
  5. face89

    face89 New Member

    11
    Aug 4, 2009
    Chicago, IL
    380 Sundancer 2000
    454 Mercruiser Mag MPI Horizon Gen VI Inboards
    My issue was only on 1 engine...so it was easier to prove the ECM was the culprit by swapping them. I'm trying to learn what others' experience is with these 20+ yr old computers. ie. whether they commonly fail or maybe just need corroded contacts cleaned up or there's a loose wire somewhere.
     
  6. face89

    face89 New Member

    11
    Aug 4, 2009
    Chicago, IL
    380 Sundancer 2000
    454 Mercruiser Mag MPI Horizon Gen VI Inboards
    And to be clear, my issue was previously only when getting hot and sitting for a few hours. But it has progressed this year to a cold start condition as well, which makes it even more curious what problem is happening with the ECM.
     
  7. dan313

    dan313 Active Member

    204
    Sep 27, 2009
    Long Island
    2005 270 Amberjack
    350 Mag Bravo3
    There is another post on this site with the same issue. Anyway my buddy just had that same problem. He thought it was the ECM. Turned out to be a bad ground on the fuel pump. The engine is running like a top now. He cancelled the purchase of the ECM. Hope this helps.
     
  8. Bill the Boater

    Bill the Boater New Member

    2
    Aug 3, 2020
    Sea Ray1998- 37EC
    3534 Mercruiser Horizens EFI inboards
    Thank you all for the input. I filled up this week with new fuel and resolved the problem.
    As the Mercruiser bulletin link recommended.I discovered there is such a thing as winter gasoline , formulated to evaporate at a lower temperature. My first fill was in April and I told the marina owner about the different types of gas.He called his supplier and confirmed that he bought winter formulated fuel in March.
    As the engine cools the winter fuel in the pumps and lines evaporates and I was trying to start the engines after a few hours the pumps couldn't prime. Summer formulated fuel can stay liquid after running the engines and and restarting after a few hours. WOW......
     
    face89 and Chris-380 like this.

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