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  1. #1

    Default Mercruiser 4.3 Thunderbolt V

    Ok guess ill give this a shot. Most of you guys seem to know more than me.
    Yesterday went to take the family and neighbors tubing. I have as 22' Bayliner Trophy with a Mercrusier 4.3 190 I/O. Got GAS at shell. Then launched and she started up fine as usual. Put her in reverse and backed away from the dock without letting it warm up enough or so i thought. Put her in gear to take off and she stalled out, I proceeded to start her again and she wouldnt start. Set there for 10-15 min because i thought i flooded her. Finally got it started again and it stalls. Got a short tow back to the dock. Set there and finally got her started Put the family on the dock and took her for a short test run. RAN GREAT! Come back to the dock and reloaded everybody. Stalls again. Got her started and let her idle to get to temp 175 degrees. Load everyone up and she stalls again. So much for tubing today. Packed thgings up and headed home Changed the fuel filter/ water seperator and it with gas to the top and put it back on. Will crank but not start. Checked the plugs they look fine plenty of spark pulled the air filter looked into the carb plenty of gas going in while in neutral giving it throttle but wont start. Spray some starting fluid into the carb and it wont even act like its going to start.

    Kinda got stumped at this point. I also put an additive into the tank to dry out any water. I used the boat almost every weekend this summer in the cheapeake bay and no problems. Lurking through the forum it seems its electricla rather than fuel to me because even when i spray starter fluid into the carb it dont react whatso ever.

    Any body got any ideas?

  2. #2

    Default Re: Mercruiser 4.3 Thunderbolt V

    Quote Originally Posted by mikecornell
    Ok guess ill give this a shot. Most of you guys seem to know more than me.
    Yesterday went to take the family and neighbors tubing. I have as 22' Bayliner Trophy with a Mercrusier 4.3 190 I/O. Got GAS at shell. Then launched and she started up fine as usual. Put her in reverse and backed away from the dock without letting it warm up enough or so i thought. Put her in gear to take off and she stalled out, I proceeded to start her again and she wouldnt start. Set there for 10-15 min because i thought i flooded her. Finally got it started again and it stalls. Got a short tow back to the dock. Set there and finally got her started Put the family on the dock and took her for a short test run. RAN GREAT! Come back to the dock and reloaded everybody. Stalls again. Got her started and let her idle to get to temp 175 degrees. Load everyone up and she stalls again. So much for tubing today. Packed thgings up and headed home Changed the fuel filter/ water seperator and it with gas to the top and put it back on. Will crank but not start. Checked the plugs they look fine plenty of spark pulled the air filter looked into the carb plenty of gas going in while in neutral giving it throttle but wont start. Spray some starting fluid into the carb and it wont even act like its going to start.

    Kinda got stumped at this point. I also put an additive into the tank to dry out any water. I used the boat almost every weekend this summer in the cheapeake bay and no problems. Lurking through the forum it seems its electricla rather than fuel to me because even when i spray starter fluid into the carb it dont react whatso ever.

    Any body got any ideas?

    Year is a 2000

  3. #3
    Honorary Moderator Emeritus Don S's Avatar
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    Default Re: Mercruiser 4.3 Thunderbolt V

    Did you check for spark? My guess since it seems to keep dying when you put it in gear is the shift cable is bad and causing the shift interrupt switch to engage when putting it into gear, and stays bound up when going back to neutral, which kills the spark.
    Don S.


    Please, no PM's (Private Messages) regarding boat/engine problems.
    That is what the forums are for.
    Only forum/moderator issues will be answered in PM's.

  4. #4

    Default Re: Mercruiser 4.3 Thunderbolt V

    Quote Originally Posted by Don
    Did you check for spark? My guess since it seems to keep dying when you put it in gear is the shift cable is bad and causing the shift interrupt switch to engage when putting it into gear, and stays bound up when going back to neutral, which kills the spark.
    Yes i checked and have spark. After getting home and changing the fuel filter i cant even get it to start. Gas is going in to the carb when i throttle and when i checked the plugs, they looked clean and were sparking 1/2 "

    However even if i add starting fluid i can not t get it to go


    Ignition coil?


  5. #5
    Honorary Moderator Emeritus Don S's Avatar
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    Default Re: Mercruiser 4.3 Thunderbolt V

    If you have spark, and you squirt starting fluid (Talk about an engine killer) into the carb and it won't even fire, Then you either don't have spark or what you suspect is gas being squirted into the engine thru the carb is actually water. If the plugs are fouled with water, they won't spark at all in the engine.
    Don S.


    Please, no PM's (Private Messages) regarding boat/engine problems.
    That is what the forums are for.
    Only forum/moderator issues will be answered in PM's.

  6. #6

    Default Re: Mercruiser 4.3 Thunderbolt V

    What i thought or my neighbor looking at my plugs thought was enough spark turned out not to be enough spark.

    Replace the ignition coil for 40 bucks and she started right up on the the 1st crank.

    i have a 65 gallon tank and put 14 gallons into it (topping it off) before the problem. i found it hard to beleive that 14 gallons fouled up the other 51 with water.

    Thanks DON S for your help

  7. #7
    Chief Petty Officer
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    Default Re: Mercruiser 4.3 Thunderbolt V

    Glad you got it running again, but I feel the need to correct you on your thought. Water settles to the bottom of the tank. Water and gas don't mix. Water settles and is picked up and fed to the engine since the pickup tube is in the bottom of the tank......Ethanol does mix in as much as it turns into a wierd kinda soup, not a puddle like in non-ethanol. It still settles to the bottom and still will not run in the motor. Just an FYI....

  8. #8
    Moderator Bondo's Avatar
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    Default Re: Mercruiser 4.3 Thunderbolt V

    Ayuh,.........

    Even if you had 500 Gallon tanks,..........

    A Quart of Water will Ruin your Day.............
    Any Grease is Better,..... Than No Grease at All.......

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