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Hello all --
Engine is a 1999 Yamaha SX200TX (0x66) with approx 1800 hours. Engine has been used several times this season and has run great. Had a problem the other day with the key switch, which needed to be replaced, and have used the boat since without any trouble.
This morning I started having the following symptoms:
1- First thing I noticed was a slightly louder thunk when I shifted into gear from neutral - engine sounded just slightly off after that point and while idling in forward gear for a few mins, with maybe a tiny bit more vibration than I would normally have at that RPM.
2 - When I went to give it power, nothing really happened when I moved the throttle forward - I got maybe another couple hundred RPMs and that was about it.
3 - When I would back into neutral, I noticed the RPMs were higher than they normally be, somewhere around 1100-1300.
4 - At one point it felt like the binnacle controls felt a little out of whack - it seemed a little harder to move the controls, but nothing too out of the ordinary.
5 - After doing a quick check and looking to see if there were any obvious mechanical linkage problems the motor ran fine for a few minutes after I restarted.
6 - Shifting back into neutral and then forward a few times and then idle speed was back up and the symptoms returned. At one point I was running up on plane and everything was fine, then the engine quickly dropped a few hundred RPM. I backed off to neutral and then put it into forward with same problems.
7 - While idling back to the dock, I had to advance the throttle a bit more than I usually would for the RPMs I was getting, and a few times the engine would suddenly jump up in RPMs again and I would back off.
8 - With the cover off, the engine definitely sounds rougher than usual.
I went back home to get my tools & diagnostics, here is what I checked:
1 - Both batteries are brand new and otherwise seem to be fine.
2 - Both low pressure fuel pumps were replaced in the spring.
3 - VST filter was inspected/cleaned in the spring.
4 - Engine is still pissing ok.
5 - Mechanical linkages seem ok, nothing seems broken or out of place. Both gear and throttle linkages appear to be adjusted correctly.
6 - I get no codes on the winky blinky, both when idling and when the problem is occurring.
7 - Fuel pressure out of the VST remains constant, even while the problem is occurring.
8 - TPS voltages check out ok, and appear to be behaving correctly when throttle is adjusted, even while problem is occurring.
9 - I had just put in new spark plugs the day before and hadn't run the boat in gear since, so put in an entirely new set to make sure I didn't have a bad plug.
Not sure where to go from here - any pointers?
Thanks,
-- Tom
Engine is a 1999 Yamaha SX200TX (0x66) with approx 1800 hours. Engine has been used several times this season and has run great. Had a problem the other day with the key switch, which needed to be replaced, and have used the boat since without any trouble.
This morning I started having the following symptoms:
1- First thing I noticed was a slightly louder thunk when I shifted into gear from neutral - engine sounded just slightly off after that point and while idling in forward gear for a few mins, with maybe a tiny bit more vibration than I would normally have at that RPM.
2 - When I went to give it power, nothing really happened when I moved the throttle forward - I got maybe another couple hundred RPMs and that was about it.
3 - When I would back into neutral, I noticed the RPMs were higher than they normally be, somewhere around 1100-1300.
4 - At one point it felt like the binnacle controls felt a little out of whack - it seemed a little harder to move the controls, but nothing too out of the ordinary.
5 - After doing a quick check and looking to see if there were any obvious mechanical linkage problems the motor ran fine for a few minutes after I restarted.
6 - Shifting back into neutral and then forward a few times and then idle speed was back up and the symptoms returned. At one point I was running up on plane and everything was fine, then the engine quickly dropped a few hundred RPM. I backed off to neutral and then put it into forward with same problems.
7 - While idling back to the dock, I had to advance the throttle a bit more than I usually would for the RPMs I was getting, and a few times the engine would suddenly jump up in RPMs again and I would back off.
8 - With the cover off, the engine definitely sounds rougher than usual.
I went back home to get my tools & diagnostics, here is what I checked:
1 - Both batteries are brand new and otherwise seem to be fine.
2 - Both low pressure fuel pumps were replaced in the spring.
3 - VST filter was inspected/cleaned in the spring.
4 - Engine is still pissing ok.
5 - Mechanical linkages seem ok, nothing seems broken or out of place. Both gear and throttle linkages appear to be adjusted correctly.
6 - I get no codes on the winky blinky, both when idling and when the problem is occurring.
7 - Fuel pressure out of the VST remains constant, even while the problem is occurring.
8 - TPS voltages check out ok, and appear to be behaving correctly when throttle is adjusted, even while problem is occurring.
9 - I had just put in new spark plugs the day before and hadn't run the boat in gear since, so put in an entirely new set to make sure I didn't have a bad plug.
Not sure where to go from here - any pointers?
Thanks,
-- Tom
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