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  • Bogging on Acceleration

    Got a 2007 50 HP TLR 2-stroke that recently started bogging down when I accelerate from idle. Once I work the throttle, it eventually accelerates and runs great. If I idle down and immediately throttle back up it's fine but if I slow to idle for more than a few seconds and accelerate, it bogs down again. Recently replaced spark plugs, fuel filter, water/fuel filter, and fuel line since symptom started a month ago. Thought I had it fixed today when I switched to a different fuel tank as initially, I didn't have problem when leaving the ramp. After running motor for 15 minutes and then *****ing after another 15, problem came back. Best guess is I need a carb rebuild but wanted to ensure there is nothing I'm missing before going down that path as the rebuild kits don't look to be cheap.

  • #2
    just clean carbs no need for kit did you check your fuel pump for holes in diaphragm

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    • #3
      Not the carb

      It took me a while to finally do it, but I cleaned the carbs and problem still exists as stated in original post. Observations from the carb project (which was an easier than I anticipated) were that the carbs were pretty clean so not surprised when that didn't fix problem. Other attempts since my last post have included replacing all the gaskets and diaphragms of the fuel pump and unrelated to the symtom I overhauled the water pump (it was time). So any suggestions as to what might be causing the problem? Something electrical perhaps?

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      • #4
        I have a topic on this issue a few pages back. 2005 50 hp two stroke. Runs fine for fif**** minutes. Full throttle no problem. Shut it off and wait a couple of minutes and it will surge when you give it the throttle, getting progressivly worse until all there is is idle.

        I have changed the plugs, the impeller, cleaned the carbs. tried it on a external tank, pumped the fuel bulb while it was not running right, checked the CDI and timing adavnce, checked the overheat buzzer(it works fine the motor is not overheating and going to limp mode)

        Now I have two of them doing the same thing. A freind of mine just bought one. He called me to see if I would look at it. It's symtoms are exactly the same. Runs fine for fif**** to twenty minutes and then no throttle.

        My next step is the take the starter primer out and look at it. If I could do away with it I would.

        Surely someone else on here has had this problem.

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        • #5
          CDIs are expensive

          Well between the three of us, someone I guess needs to take one for the team and buy a new CDI and see if that fixes the problem. It appears our symptoms are the same. From what I've read, there is no easy way to test a CDI either. The only way I see to truly test one is replace it and see if that corrects the problem. I'm out of other ideas so if someone else has a suggestion before I drop the cash, please reply. Every motor I've owned has needed a new CDI at some point so even if this isn't the problem, figure I'll need it at some point.

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          • #6
            The CDI input and output voltages are easy to test with a peak reading meter made for these ignition systems or a DVA adapter with a regular meter just like the Yamaha service manual states. All it is is a capacitor that is charged up with the charge coil under flywheel and then is discharged to the coils when the pulsar coils tell it to , but the timing can altered by the temperature of the motor and the internal TPS that the throttle link is attached to. Timing can be monitored with a timing light to see if it is doing what it is suppose to.

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            • #7
              I got the motor to malfunction in the test tank. It would idle fine but would not take the throttle. At that point I started checking the spark and timing with a timing light. I could find no problem with the CDI. All three cylinders had good spark and right on time. Next I dissconnected the timing arm on the side of the CDI and mover the arm manually with the light on the timing marks. The timing advanced as it should. That pretty much eliminated the CDI in my mind. Maybe I'm wrong.

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              • #8
                Originally posted by MJohnston7 View Post
                Well between the three of us, someone I guess needs to take one for the team and buy a new CDI and see if that fixes the problem. It appears our symptoms are the same. From what I've read, there is no easy way to test a CDI either. The only way I see to truly test one is replace it and see if that corrects the problem. I'm out of other ideas so if someone else has a suggestion before I drop the cash, please reply. Every motor I've owned has needed a new CDI at some point so even if this isn't the problem, figure I'll need it at some point.
                Well I was wrong. Not the first time.
                Mjohnston7. It looks like I'll be the one to take one for the team. Here's what I did. I took the boat to the river and had a freind with me. I left the hood off the motor and ran it up and down the river for an hour shutting it off restarting, idle, full throttle. No problems. I put the hood back on and ran four a couple of miles and shut it off and let it sit. Restarted the motor and it did the same old thing. Go to give it throttle and it just dies. Nothing but idle.
                I fiddle with everything for twenty minutes. Took the drain plugs out of the carbs. They were full of fuel. Messed with the primer positions no help. Disconnected the timimg arm and manualy moved it slowly a couple of degrees while in forward idleing and the rpms rose slightly. I moved it a little more and had my freind give the engine a little throttle and the rpms rose more. I slowly moved the timing arm up while he slowly gave it full throttle and it went to full rpm's. I snapped the timing arm back on and we rode around for another twenty minutes with the hood off and it ran perfectly the rest of trip. Stopped, started, idle, full throttle. Everything worked.
                I can either break down and buy a new cdi or just use it with the hood off.

                I don't care for the timing advance in with the cdi. Bad idea. Just one more thing to go wrong with the cdi and at the price they want for one I can't afford to replace to many.

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