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Results 1 to 17 of 17
  1. #1

    Default 2007 Mercury 2 stroke 50 HP (Oil Injected) flooding at same point in accelaration

    I am a newbie to the forum and relatively new to boating. I bought a 16 foot pontoon boat with this engine used. It had less than 30 hours on it, but the motor still had all the factory parts - so never serviced. I had my local marine shop replace the plugs, water pump, fuel line and drained and replaced all oil/gas/etc. In addition, I had all 3 carburetors rebuilt and new impellers installed before ever running the boat. I took it out the first time and had the same problem I am having now. I brought it back in and due to a terrible explanation of the engine's lack of performance, I now have a new tach. I took it back 2 weeks ago with a much better feeling they understood my issue, and it was discovered that the fuel pump was not checked by a now fired mechanic. It was very dirty and the diaphram's in need of attention. It is now rebuilt. To no avail unfortunately.

    I have taken this boat out 20-25 times, and here's my problem. It will run fine at times and give me what most would call peak performance. After a while, it starts flooding. Sometimes this problem starts from the minute we leave the launch. It is always at 3,000 RPM's that it will flood and drop to 1,000 RPM's before catching and revving back up, but once this problem starts I never get back to peak performance. Pulling 2 little boys under 6 on a tube makes the flooding worse at all throttle stages and not just at the acceleration point that it always floods.

    Today, after getting the rebuilt fuel pump yesterday, I got great performance for about 20 minutes. Then in a turn, it flooded and lost RPM's and the rest of the day was more of the same.

    I am at my wits end. It should be noted that my mechanic has not put the boat in the water. It idles fine and revs as high as to dangerous levels on the water hose without missing or flooding.

    Does anyone have a clue? Fuel system is basically all rebuilt and cleaned, so could it be electric? If you will, forget that it performs well at times. While that is true and may be important, what is the cause of a flooding engine at the same level of acceleration? Maybe that will lead me in the right direction.

    Thanks in advance.
    Last edited by showssc; 07-23-2011 at 10:52 PM. Reason: Edited to correct typos.

  2. #2
    Join Date
    Jun 2010
    Location
    Milton, Fl
    Posts
    546

    Default Re: 2007 Mercury 2 stroke 50 HP (Oil Injected) flooding at same point in accelaration

    what makes you think it's flooding? is there gas running out of the carbs? does it do this everytime out?

    you said " It idles fine and revs as high as to dangerous levels on the water hose without missing or flooding." DON'T DO THAT!!! you will end up with a runaway motor and have a very good chance of blowing the thing up.... and you with it.....

  3. #3

    Default Re: 2007 Mercury 2 stroke 50 HP (Oil Injected) flooding at same point in accelaration

    As to idling to dangerous levels, my mechanic did that. He was adjusting the friction level on the control box and had it too loose when he fired it up, but sincere thanks for the heads up. He just told me that it shot straight up without a miss or a flood. I never get above 2,000 RPMs on the hose.

    It does do it every time out, but sometimes I will not experience this problem until a half hour or so after launching. Other times, it starts from the minute we put it in the water. Nonetheless, I have never taken it out without this problem occuring.

    I say flooding just because it doesn't seem like a miss. It could be a stall, but flooding seems the more appropriate explanation for the performance. Does that make sense? I am a novice and have not checked the carbs. I welcome any guidance on how to do that.
    Last edited by showssc; 07-23-2011 at 11:55 PM.

  4. #4
    Join Date
    Jun 2010
    Location
    Milton, Fl
    Posts
    546

    Default Re: 2007 Mercury 2 stroke 50 HP (Oil Injected) flooding at same point in accelaration

    A fast check for you is to have someone back by the fuel hose, when the motor starts to lose rpms have them pump the fuel bulb a few times and see if the motor picks back up speed. (this bypasses the fuel pump by forcing fuel into the carbs). also when you start loseing rpms is the fuel bulb hard or soft?

  5. #5

    Default Re: 2007 Mercury 2 stroke 50 HP (Oil Injected) flooding at same point in accelaration

    I am not sure at the exact moment the engine loses RPM's, but I do know that it is often soft after the problem begins. I replaced the fuel line for this very reason, but the problem persists. It is hard as a rock after manually pumping it to start, but I have checked it after problematic performance, and it is not hard even with the new fuel line.

    It would be a difficult check as you describe. The flooding/stalling is less than 5 seconds. If I ease up on the throttle or if I go hard on the throttle, it stalls at 3,000 for 3-5 seconds and then revs past 3,000 quickly. I know enough to know that RPM's are not a good indicator on engine performance, but once this problem starts, I never get maximum RPM's or engine performance from the motor. So, it is more than just the flood/stall on acceleration. I just think that the fact that it does it at this exact point every time it is messing up has to be an indicator to the problem.

  6. #6
    Join Date
    Sep 2003
    Location
    New Tripoli, PA, USA!
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    12,419

    Default Re: 2007 Mercury 2 stroke 50 HP (Oil Injected) flooding at same point in accelaration

    Sounds to me like it has the opposite problem; it's starving for gas. Have your mechanic open up the idle mixture screws 1/4 turn CCW.

    Jeff

  7. #7

    Default Re: 2007 Mercury 2 stroke 50 HP (Oil Injected) flooding at same point in accelaration

    Also, I am taking it out again tomorrow. If I have someone pump the bulb as I approach the problem area in acceleration, what am I learning if the problem is cured or lessened? Alternatively, what have I crossed off the list if that doesn't affect performance?

  8. #8
    Join Date
    Jun 2010
    Location
    Milton, Fl
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    546

    Default Re: 2007 Mercury 2 stroke 50 HP (Oil Injected) flooding at same point in accelaration

    it sounds like it the carbs to me, but we need to do the bulb check first to make sure its not the fuel pump.. do you have a temp gage on the boat? does the horn sound when you turn the key on?

  9. #9

    Default Re: 2007 Mercury 2 stroke 50 HP (Oil Injected) flooding at same point in accelaration

    No horn or warnings have sounded. I do not have a temp guage on the boat. We beach and let kids play often, and the performance does not change after a half hour to 2 hours cooling time. Once the problem starts, it persists. The only time I have seen it cease is after service or at least a couple weeks rest time.

    I know that sounds vague and crazy, but thus my perplexed state of mind. I can not tell you all how much I appreciate the dialogue. The same mechanic who never checked the now discoverd gunked up fuel pump rebuilt the carbs. Maybe I need to have the other mechanic check said rebuit carbs.

    P.S. I am not one to question the quality of a man's work who is much more qualified than myself, but I do know that the carb rebuilder installed an unneeded new tach, short cut the wiring by piggy backing off the lighting system and caused me to lose funcitionality of all my lights. The second mechanic who rebuilt the fuel pump discovered the wiring/circuit issues with my lights.

  10. #10
    Join Date
    Jun 2010
    Location
    Milton, Fl
    Posts
    546

    Default Re: 2007 Mercury 2 stroke 50 HP (Oil Injected) flooding at same point in accelaration

    the bulb is checking the fuel pump, Jeff above is saying the same thing I am, sounds like the carbs, but fuel pump is a easy check while out on the water, if it fixes it, have the fuel pump rebuilt again if not, have the carbs rechecked and as Jeff said come out a 1/4 turn on the idle screws.

  11. #11

    Default Re: 2007 Mercury 2 stroke 50 HP (Oil Injected) flooding at same point in accelaration

    Thanks cuoeytwo and Jeff. I am most appreciative. I will test the fuel pump tomorrow, and if that does not work, I will have the carbs rebuilt again. I guess it is possible that the dirty fuel pump could have gunked up the carbs in as little as 3-4 months even if I assume the original rebuild was without issue. Thanks guys.

  12. #12
    Join Date
    Sep 2010
    Location
    ontario
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    9,621

    Default Re: 2007 Mercury 2 stroke 50 HP (Oil Injected) flooding at same point in accelaration

    Use a timing light and verify ignition performance on all cylinders goint to full throttle.

  13. #13

    Default Re: 2007 Mercury 2 stroke 50 HP (Oil Injected) flooding at same point in accelaration

    Did not get to the lake yesterday, but I am headed out this afternoon if the rain stays away. I went ahead and opened the idle screws a quarter turn myself. I plan on adjusting that on water and under load to see if I can solve this problem. I will report back, but I can not thank you guys enough for giving me your insight.

  14. #14

    Post Good news but no clue why.

    First, I ruled out the fuel pump as my problem. Pumping the primer had zero affect on my 3,000 RPM bog. So, I spent the better part of an hour doing 1/8 turns on my idle mixture screws. I went a full turn and a half CCW with no change on slot hole performance. Due to an obvious increase in smoke, I went back to the original position. I then went CW in 3 1/8 turns. Once again, no change. I then went to WOT to show my buddy how it will bog in sharp turns. It bogged worse than usual, but when it caught, I hit 5,000 rpm's for the first time since the fuel pump was replaced. We rode around near WOT for a bit, and it was peak performance the whole time. I backed off and tested acceleration a few times, and I eased through my problem spot with no bog. Damned if I know. In the past, it got worse the longer I ran it. Today, the opposite. I left the lake getting peak performance, and I was within 1/8 a turn on the idle mixture screws as I have been all summer. If this is familiar to anyone, I will buy you a gift card to the place of your choice. If not, I guess I will be optimistic and hope it cured itself.

  15. #15
    Join Date
    Jun 2010
    Location
    Milton, Fl
    Posts
    546

    Default Re: 2007 Mercury 2 stroke 50 HP (Oil Injected) flooding at same point in accelaration

    I hope it fixed itself..... the good thing is how much you learned about your motor....

  16. #16

    Default No doubt cuoeytwo. I had to think about what

    CCW was a few nights ago. Ha. I am doubtful, but optimistic nonetheless. That's just my lot and way in life. Thanks again for taking the time to help someone as uninformed as me.

  17. #17
    Join Date
    Sep 2003
    Location
    New Tripoli, PA, USA!
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    12,419

    Default Re: 2007 Mercury 2 stroke 50 HP (Oil Injected) flooding at same point in accelaration

    You went way too far, and you made your adjustments way too quickly. Adjusting the idle is a sensitive deal: Make 1/4 of a turn adjustments at a time, wait 10 seconds for the motor to equalize, then dial some more. Going hog wild like you did is like tossing darts at the sports page to see who'll win today's game.

    You're not out of the woods yet. What you need to do now is this: Tie the boat to a dock (or on the trailer). Warm the motor thoroughly. Put her in gear and advance the throttle to a point BEFORE where the carbs open. Then SLOWLY dial in each carb until you get best idle. Finally, do the carb blip open deal I described above to eliminate the bog.

    Jeff

    PS: I use an infrared temp gun on the plug bodies to get them all the same temperaure. Then go to the anti-bog adjustment.

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