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    Carburetor question on restoration I’m working on 1992 40 hp MSHQ Yamaha

    Your second picture shows the fuel pump on the block, not on the carb. If the diaphragm is damaged, it will dump excess fuel into cylinder 3 only. Please see my post #7 on how to check if it's damaged. It's quick and easy and will rule out pump problems.
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    Carburetor question on restoration I’m working on 1992 40 hp MSHQ Yamaha

    I will bow to your greater knowledge, but I was under the impression that the fuel pump it has, works by taking the vacuum from the No. 3 cylinder crankcase, just like most of the other 3-cylinder 2T yams. If so, then a leaking diaphragm empties fuel into the No. 3 cylinder only. It's happened...
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    Carburetor question on restoration I’m working on 1992 40 hp MSHQ Yamaha

    Fuel pumps can leak into cylinder 3 if the diaphragm is damaged. Take it off (2 bolts), but leave the fuel lines attached. Pump the fuel bulb and see if ANY fuel comes out of the hole on the back. If it does, then a new pump, or repair kit is needed.
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    2005 Yamaha 70B running rich

    I've now been down to the boat and pulled the Primestart. When hooked up to 12v, it takes about 1.5 mins to fully extend, so I would call that good-to-go. However, I also decided to pull the diaphragm and manual lever out again to have a look, as I was also told that the little 'O' ring on the...
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    2005 Yamaha 70B running rich

    Thanks for that. I pulled the Primestart apart to clean it when I did the carbs, and the diaphragm was perfect, however, I didn't check the working of the needle. I can't get to the boat for a few days, but I will check that as soon as I get to it. Cheers, Paul
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    2005 Yamaha 70B running rich

    Hi, Firstly, sorry for the long post !!! About 6 months ago I bought a 2004 Yamaha 70B outboard (same as the 50G and 60F) from a guy who had owned it from new. It had been sat in his shed for over a year because it was "unreliable" - It didn't start very easily and stopped giving enough power...
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