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  1. O

    7.4mpi just started running rough and with gas coming out exhaust

    Sure glad I changed the oil. I had about 3 qts more than I should have. At least I started with straight 40w.
  2. O

    7.4mpi just started running rough and with gas coming out exhaust

    New ECM is in. The mefi4 with the adaptor harness from OBD. Boat seems to run good but the power curve feels slightly different. Nothing anyone except me would notice. I need to change the oil again to be safe. I’m sure plenty washed down from my testing. I have to repair one of the...
  3. O

    7.4mpi just started running rough and with gas coming out exhaust

    Anything to make sure injectors themselves are not a problem other than measuring resistance? Looks like I will be getting a mefi4 with the conversion harness.
  4. O

    7.4mpi just started running rough and with gas coming out exhaust

    How should I test the harness with a multimeter from the injector to the ECM connector to be absolutely certain I don’t have something that will cause a problem for the new $2500 ECM? All injectors read 12.9 resistance from what I recall - all were the same. I am just second guessing...
  5. O

    7.4mpi just started running rough and with gas coming out exhaust

    FINAL UPDATE - fried injector driver. Not repairable. How difficult is removing the entire harness between the ECM and injectors? I know the short injector harness come off easily. I want to look at every inch of wire before I put in a $$$ ECM.
  6. O

    7.4mpi just started running rough and with gas coming out exhaust

    I think this post explains what we we all missing. See #5 by John Marzetti of Boats Unlimited. My engine is an L29. https://www.offshoreonly.com/forums/general-q/332476-7-4l-mpi-wont-start.html#post4376566 He explains the unique injector banks.
  7. O

    7.4mpi just started running rough and with gas coming out exhaust

    The only other thing I can think of is the opposite side of the ECM - not the wires going to the injectors. Maybe a pin isn’t being powered or receiving full power? Maybe a relay?
  8. O

    7.4mpi just started running rough and with gas coming out exhaust

    I will send it to OBD. I know the banks fire in a different order but the odd side holds 12v on both injector leads until it grounds and fires. The even side is 12v on the power side and 8v on the ECM side which makes it act sorta like a ground. The noid light is on solid but dim. All it...
  9. O

    7.4mpi just started running rough and with gas coming out exhaust

    Bumping up the resistance setting, all read about 293 resistance Key off.
  10. O

    7.4mpi just started running rough and with gas coming out exhaust

    Ignition on - the noid light is on solid on 2 4 6 8 and off on 1 3 5 7
  11. O

    7.4mpi just started running rough and with gas coming out exhaust

    Should both j1-1 and j1-17 have power when the ECM is removed and the key is on? This is a MEFI 3
  12. O

    7.4mpi just started running rough and with gas coming out exhaust

    About to head back to the boat if you can think of any tests to try
  13. O

    7.4mpi just started running rough and with gas coming out exhaust

    My injector plugs are numbered and connected correctly. 2, 4, 6 and 8 on the starboard side. I will see if the voltage readings ever change. I will also look to see if any colors match. Maybe the banks are really different than just evens and odds. The spark plugs were definitely only...
  14. O

    7.4mpi just started running rough and with gas coming out exhaust

    I think the L29 fires all evens and all odds doesn’t it? I am particularly focused on why the voltage on the even side wires from the ECM is almost 5v lower when only the key is on. That is a unique voltage drop.
  15. O

    7.4mpi just started running rough and with gas coming out exhaust

    Mine has the unused regulator but I don’t recall any fuel in the vacuum hose.
  16. O

    7.4mpi just started running rough and with gas coming out exhaust

    Yes, pink power to all and different colors for the ECM side connections.
  17. O

    7.4mpi just started running rough and with gas coming out exhaust

    I will recheck continuity but I am fairly certain each check returned infinity. I don’t recall any test I attempted show resistance. Some appeared to change the numbers for half a second before showing infinity. Should I do this with the ECM connected and only 1 injector lead disconnected...
  18. O

    7.4mpi just started running rough and with gas coming out exhaust

    Doing this, the odd bank shows 12v on both connectors at an injector. The even bank shows 12v on the power connector and 8v on the wire that goes to the ECM. All disconnected reads 12v on one side and none on the ECM wires. Plug any injector in and the first paragraph happens. All...
  19. O

    7.4mpi just started running rough and with gas coming out exhaust

    I'm still researching and will go back for more testing with the meter. What I noticed yesterday with the NOID light on the #2 connector was: Key off, light off. Key on, light on but dim and solid, Running light on very bright and solid. I gather all even injectors have a common connection...
  20. O

    7.4mpi just started running rough and with gas coming out exhaust

    How exactly? Test light from battery to the injector connector when the key is off? Anything else?
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