Motor starts and runs great until wot. she flat lines at 4k rpms. changed plugs, fresh fuel. I'm stumped. Always ran strong until now. Need some pointers , thanks
seems to be getting fuel???? you never know, and with ethonal there is always a potental problem... Clean filters, disconnect the fuel line from the engine and hook it direct to a fuel source, remember to pre-mix if your engine uses a external oil injection system and give it a try.
If it still craps out try pumping the fuel bulb while running at wot...
cleaned filters before winterization, have the fuel line hooked directly from pump to tank. pulled plugs ( fuel residue on all the plugs) fuel is getting to plugs. also tried pumping the bulb at wot , bulb was solid with no change in rpms.
Could also be a failing stator. Check stator resistance cold then after it's fully warmed, if it changes drastically or if the Hi or Low Speed windings' resistance is out of spec, the stator is bad.
Note that resistance readings alone sometimes cannot pick up a marginal stator, for that you may need to take voltage readings, which requires a Direct Voltage Adapter to allow your mulitmeter to read peak voltages.
Here's a couple of threads with info on building an inexpensive adapter:
Being able to read peak voltages with a DVA will also allow you to check your switchboxes, otherwise pretty difficult to do.
Also check to make sure the throttle butterflies are fully opened at full throttle, and you're getting maximum spark advance as well. You can check these without running the motor.
Another possibility is carbon buildup in the tuner plate, exhaust tube, or some other type of obstruction down the line. Not so likely but if you can't find anything else, you could pull the lower unit and look up the midsection with a strong light.
