Hi - New to the board. Search had great info, but just not exactly my setup.
I've got an Escape 209 with a 95 Yamaha 150 SW2. I've lost about 600rpm off my top end. It's used to put out 5300-5400rpm and now tops out at 4700. Starts, idles, and runs strong right up to 4700 then stays there. No sputter or misfire. No slow degradation from 5300. The last 30 degrees of throttle throw seems to have no effect where it used to.
I've checked the throttle rigging, and all looks normal there. Inspected and replaced all the spark plugs. All looked normal there. Replaced the fuel filter which had a little debris, but this had no effect. I'll replace the fuel pump diaphragms tomorrow and check pressure/vaccuum. If still no luck, it's onto the carbs. Fuel is new. I'm going to get a compression tester this weekend, but I doubt its that since it didn't gradually degrad and seems to run normal through the low to mid range. Is that a good assumption?
Would a clogged high pressure jet in one of the carbs cause this drop in RPM? Can't imagine all the WOT jets would clog at the same time...but possible. Any sensor to check that might be limiting the system? I welcome any other suggestions?
I've got an Escape 209 with a 95 Yamaha 150 SW2. I've lost about 600rpm off my top end. It's used to put out 5300-5400rpm and now tops out at 4700. Starts, idles, and runs strong right up to 4700 then stays there. No sputter or misfire. No slow degradation from 5300. The last 30 degrees of throttle throw seems to have no effect where it used to.
I've checked the throttle rigging, and all looks normal there. Inspected and replaced all the spark plugs. All looked normal there. Replaced the fuel filter which had a little debris, but this had no effect. I'll replace the fuel pump diaphragms tomorrow and check pressure/vaccuum. If still no luck, it's onto the carbs. Fuel is new. I'm going to get a compression tester this weekend, but I doubt its that since it didn't gradually degrad and seems to run normal through the low to mid range. Is that a good assumption?
Would a clogged high pressure jet in one of the carbs cause this drop in RPM? Can't imagine all the WOT jets would clog at the same time...but possible. Any sensor to check that might be limiting the system? I welcome any other suggestions?