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#1
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Last year I bought an old boat with a 55 hp, twin cylinder. Idled fine but
wouldn't open up. Rebuilt carbs and discovered that two screws came off the air box and were sucked into the reed valves on one carb, holding a reed open. Fixed that and engine ran fine. But next week it was back to stumbling and killing when throttles were opened up. Due to floods, I just got a chance to pull the shroud and look around it. I see a hose (vacuum?) that runs from the front of the engine housing (intake manifold) to the back of the air box had pulled loose from the air box (or I had forgotten to attach it firmly). Any idea of the function of this hose and the ramifications of it not being connected correctly? My shop manual doesn't refer to it or show it. Tom. |
#2
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On Wed, 27 Aug 2008 00:48:02 GMT, "Tom G"
wrote: Last year I bought an old boat with a 55 hp, twin cylinder. Idled fine but wouldn't open up. Rebuilt carbs and discovered that two screws came off the air box and were sucked into the reed valves on one carb, holding a reed open. Fixed that and engine ran fine. But next week it was back to stumbling and killing when throttles were opened up. Due to floods, I just got a chance to pull the shroud and look around it. I see a hose (vacuum?) that runs from the front of the engine housing (intake manifold) to the back of the air box had pulled loose from the air box (or I had forgotten to attach it firmly). Any idea of the function of this hose and the ramifications of it not being connected correctly? My shop manual doesn't refer to it or show it. I don't know what it does either (my guess is it's some kind of breather/equalization line), but I had a similar engine, did similar repairs, couldn't find it in the manual so just hooked it up. One thing I did have a problem with is timing advance which, in theory, should work off vacuum, but that seemed to clear up also. Just some food for thought - nothing constructive. |
#3
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Short Wave Sportfishing wrote:
On Wed, 27 Aug 2008 00:48:02 GMT, "Tom G" wrote: Last year I bought an old boat with a 55 hp, twin cylinder. Idled fine but wouldn't open up. Rebuilt carbs and discovered that two screws came off the air box and were sucked into the reed valves on one carb, holding a reed open. Fixed that and engine ran fine. But next week it was back to stumbling and killing when throttles were opened up. Due to floods, I just got a chance to pull the shroud and look around it. I see a hose (vacuum?) that runs from the front of the engine housing (intake manifold) to the back of the air box had pulled loose from the air box (or I had forgotten to attach it firmly). Any idea of the function of this hose and the ramifications of it not being connected correctly? My shop manual doesn't refer to it or show it. I don't know what it does either (my guess is it's some kind of breather/equalization line), but I had a similar engine, did similar repairs, couldn't find it in the manual so just hooked it up. One thing I did have a problem with is timing advance which, in theory, should work off vacuum, but that seemed to clear up also. Just some food for thought - nothing constructive. Timing is either electronically controlled or by means of flyweights and springs under the distributor baseplate on an inboard. On an outboard there is a timing plate connected to the carb linkage. I'm guessing that the hose might be operating the fuel pump with crankcase pulsations. |
#4
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On Wed, 27 Aug 2008 06:29:37 -0400, Jim wrote:
Short Wave Sportfishing wrote: On Wed, 27 Aug 2008 00:48:02 GMT, "Tom G" wrote: Last year I bought an old boat with a 55 hp, twin cylinder. Idled fine but wouldn't open up. Rebuilt carbs and discovered that two screws came off the air box and were sucked into the reed valves on one carb, holding a reed open. Fixed that and engine ran fine. But next week it was back to stumbling and killing when throttles were opened up. Due to floods, I just got a chance to pull the shroud and look around it. I see a hose (vacuum?) that runs from the front of the engine housing (intake manifold) to the back of the air box had pulled loose from the air box (or I had forgotten to attach it firmly). Any idea of the function of this hose and the ramifications of it not being connected correctly? My shop manual doesn't refer to it or show it. I don't know what it does either (my guess is it's some kind of breather/equalization line), but I had a similar engine, did similar repairs, couldn't find it in the manual so just hooked it up. One thing I did have a problem with is timing advance which, in theory, should work off vacuum, but that seemed to clear up also. Just some food for thought - nothing constructive. Timing is either electronically controlled or by means of flyweights and springs under the distributor baseplate on an inboard. On an outboard there is a timing plate connected to the carb linkage. Ah - well, I always thought it worked like a tractor. Apparently not. I WAS WRONG!!! My day is ruined. Thanks a lot. :) I'm guessing that the hose might be operating the fuel pump with crankcase pulsations. That could be - it's been a while since I've rebuilt an outboard. |
#5
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"Tom G" wrote in message
news:6v1tk.824$p72.2@trnddc05... Last year I bought an old boat with a 55 hp, twin cylinder. Idled fine but wouldn't open up. Rebuilt carbs and discovered that two screws came off the air box and were sucked into the reed valves on one carb, holding a reed open. Fixed that and engine ran fine. But next week it was back to stumbling and killing when throttles were opened up. Due to floods, I just got a chance to pull the shroud and look around it. I see a hose (vacuum?) that runs from the front of the engine housing (intake manifold) to the back of the air box had pulled loose from the air box (or I had forgotten to attach it firmly). Any idea of the function of this hose and the ramifications of it not being connected correctly? My shop manual doesn't refer to it or show it. Tom. Similar hose on our jet ski runs a diaphram fuel pump. |
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