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  1. #1
    Join Date
    Oct 2016
    Location
    Maine
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    141

    Default Boat runs then stalls underway, then starts right up

    2004 350 MAG #0W010098

    Ideas?

    Based on threads the oil pressure sender switch ( P/N: 8M0068784 ?) appears/seems to be the culprit. Can you tell where the sender is physically located on the engine? Like to take it out in the water and have hatch supports and dividers to remove. I have a remote oil filter.

    Iím thinking I can test it like Jack says in the threads, but the boat is almost 20 years old. I also understand the sender is a problem. thanks

  2. #2
    Join Date
    Sep 2008
    Location
    Maryland - USA
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    9,204

    Default Re: Boat runs then stalls underway, then starts right up

    the part you listed is a sending unit, not a switch...

    I'd be inclined to check for fuel pressure (or lack there of) as a first step...

  3. #3
    Join Date
    Oct 2016
    Location
    Maine
    Posts
    141

    Default Re: Boat runs then stalls underway, then starts right up

    Mark - Do you have a oil switch P/N and where is this equipment on the engine.

    Understood about fuel pressure. Seems to happen underway, I need to take a ride look at rpm

  4. #4
    Join Date
    Oct 2016
    Location
    Maine
    Posts
    141

    Default Re: Boat runs then stalls underway, then starts right up

    Mark I have P/N: 881879T11

  5. #5
    Join Date
    Sep 2008
    Location
    Maryland - USA
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    9,204

    Default Re: Boat runs then stalls underway, then starts right up

    thats a SENSOR, not a switch...

    Does that engine the the 555 ECU on it?

  6. #6
    Join Date
    Oct 2016
    Location
    Maine
    Posts
    141

    Default Re: Boat runs then stalls underway, then starts right up

    It has a 864377T05 ECM module 350 MAG MPI bravo standard {open) Cooling 0W029410 below

    e.g. IPB
    (350 CU IN) V8 GM]/[350 MAG MPI BRAVO]/[ [0M600000 THRU 0W059999] - Cat.# 90-884717]

  7. #7
    Join Date
    Sep 2008
    Location
    Maryland - USA
    Posts
    9,204

    Default Re: Boat runs then stalls underway, then starts right up

    pretty sure that's a 555 ECU...I'm pretty certain there is no oil pressure switch controlling the fuel pump on that configuration.

  8. #8
    Join Date
    Oct 2016
    Location
    Maine
    Posts
    141

    Default Re: Boat runs then stalls underway, then starts right up

    IPB shows just the oil sender & sensor. I can dump and inspect the contents fuel separator filer but that's not it (new filter few hours old). Filled the tank w/gas before I put it in the water- vent worked fine. I can check the regular suspects but it appears its starved for fuel.

    Any additional thoughts appreciated Thanks

  9. #9
    Join Date
    Sep 2008
    Location
    Maryland - USA
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    9,204

    Default Re: Boat runs then stalls underway, then starts right up

    Check the fuel pressure...it has to be consistent under load as well as at idle...

    a Scan tool to check for codes and verify sensor inputs is another good step...

  10. #10
    Join Date
    Oct 2016
    Location
    Maine
    Posts
    141

    Default Re: Boat runs then stalls underway, then starts right up

    Thanks mark, after quizzing the captain (daughter), I'm going to put a set of plug-in. I ignored tuning-up the boat for for several years. The lake boat spends its life at the sandbar, and boat/restaurant tie-ups (2004 boat with 400 hours). I report back. Maybe I should put plugs in every other year with a cap. Thanks.

  11. #11
    Join Date
    Sep 2008
    Location
    Maryland - USA
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    9,204

    Default Re: Boat runs then stalls underway, then starts right up

    If you use the boat with some regularity, using the platinum tipped spark plugs can help extend the maintenance intervals....Caps usually last a few seasons but your history is the best source...

  12. #12
    Join Date
    Oct 2016
    Location
    Maine
    Posts
    141

    Default Re: Boat runs then stalls underway, then starts right up

    FYI – Service Bulletin (SB) 2006-03 says use P/N: 33-884019 (AC 41-932) Spark Plugs, however, the 33-884019 Spark Plug has been superseded (another SB?) to plug P/N: 8M2018369 which equates to NGK # 5599 Laser Iridium Spark Plug P/N: ITR4A15 (Gap .060”). This is the plug I removed & installed originally.


    BTDoctor told me years ago how to shave (grind) down a socket to fit under the manifolds. You grind down the 3/8 end of the socket not the 5/8” end.
    I hope I can get the boots off.

    Need to learn how to use dielectric grease on plugs. I believe the grease goes on the boot and the ceramic portion of the plug NOT the connection points (use Q-tip). Hope this helps somebody
    Last edited by sab; 06-20-2022 at 10:19 AM. Reason: It's P/N: ITR4A15 not P/N: ITR4A1

  13. #13
    Join Date
    Sep 2008
    Location
    Maryland - USA
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    Default Re: Boat runs then stalls underway, then starts right up

    you can use the iridium plugs...and they should last for years...

    For the boots, they make pliers for that purpose...i usually twist the boots to break them free from the plug's ceramic before trying to remove them.

    FWIW, I've found the q-tip will start 'shedding' after a few boots are done...just clip off the fuzz ball on the end and use the 'stick' - it won't leave anything to cause problems...

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