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Good Morning: I could sure use some help with this potential fuel leakage problem. Pumping the primer bulb used to result in a tight bulb (almost no flex once carb bowls were full. Now, bulb begins to stiffen but always maintains some flex. Wait 30 seconds and flex increases (pumping more fuel). I've installed a new primer bulb. Replaced both engine fuel pumps with-in the last year (bulb would stay tight at this point). Fuel lines are in good shape. No visible fuel leakage. Had trouble getting the carb needle valves to seat last year and you guys were very helpful in repairing this. Before this work, fuel would flow out one or more of the carb throats when primed. Now, no visible fuel leakage with engine tilted up and primed. Yamaha manual mentions a 'Fuel Joint' (just before in engine fuel filter) which has a check valve but my engine seems to be lacking this device. I have a 'Mity Vac' and will check the new fuel pumps. Engine appears to start right up and idle nicely. But any fuel leak poses a problem. #2 carb did exhibit the fuel leakage through the throat when primed. Removed carb & bowls. Inverted floats using gravity to make seal and pressurized fuel intake line. Each side held up to 22 psig. This is just where all the carbs held after last year's work. Not sure why the leakage but put in new Yamaha needle valves. Re-installed carb and now no leakage when primed. Still, if I can continue to pump the primer, fuel must be going somewhere. Any comments/suggestions will be appreciated.
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May have found the problem(s): Removed top fuel pump and tested with Mity Vac per manual. Total failure when pressurizing the outlet port. Replaced with my spare pump which tested fine (soaked pumps in fuel before testing). Didn't figure lower pump would also be bad as both operating pumps were almost new. Loosened mounting bolts on lower pump and primed system. Gas leaked out the back of the pump. Ordered two new pumps. Shouldn't these things last longer? Tried to repair as these are pretty simple but no success. Best bet at least for the lower pump would be a rip/hole in the diaphram. Would appreciate any comments as I'm not real good at this. -
I have had Yamaha motors for many years, I am a " ok" mechanic , but have never been able to rebuild those fuel pumps , hell I have a 25 hp old Johnson perch boat motor , cannot rebuild that fuel pump either, I just buy new ones .maybe lazy , but it is just easier , let us know how you end upComment
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lean sneeze will get them (even new ones)with the over pressure in crankcase probablyComment
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OK must ask - What is a lean sneeze?Comment
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