'99 DF50 has unstable combustion in gear, on water, over 3000-3500rpm. Reduces speed automatically, doesn't quit running. No warning lights or beeps. Bulb begins to get softer over 2000rpm. However, in my driveway, on garden hose, can go over 6000rpm no issue.
Findings so far: replacing fuel water separator, low pressure filter clean, high pressure filter did not improve situation. Tank is non-epa and seems to vent fine through cap. I am wondering if the o-ring on the vent screw is restricting air flow, maybe I should remove cap next time on water. Tank tube is free of obstruction. Bulb arrow points toward engine. No obvious fuel leaks. VST drainage is clean. Battery voltage with engine on and off is okay. Cooling seems okay (strong warm pee stream). Spark plugs are good. Fuel is good. I saw some posts on neutral switch, mine has a hairline crack in the switch body, but I don't suspect it since engine runs over 6000rpm out of water (no load). I haven't tried fuel pressure test. I haven't checked compression either. I haven't opened up the VST. I haven't hooked it up to a computer. I'm hoping it's something simple. Any suggestions are greatly appreciated!
Findings so far: replacing fuel water separator, low pressure filter clean, high pressure filter did not improve situation. Tank is non-epa and seems to vent fine through cap. I am wondering if the o-ring on the vent screw is restricting air flow, maybe I should remove cap next time on water. Tank tube is free of obstruction. Bulb arrow points toward engine. No obvious fuel leaks. VST drainage is clean. Battery voltage with engine on and off is okay. Cooling seems okay (strong warm pee stream). Spark plugs are good. Fuel is good. I saw some posts on neutral switch, mine has a hairline crack in the switch body, but I don't suspect it since engine runs over 6000rpm out of water (no load). I haven't tried fuel pressure test. I haven't checked compression either. I haven't opened up the VST. I haven't hooked it up to a computer. I'm hoping it's something simple. Any suggestions are greatly appreciated!