Remove lower unit.-----Use a strong flashlight and look for blockage in the exhaust housing.---Costs time but no $$$---And what does compression read ?----And is this issue something that showed up suddenly ?
compression is 120 psi on all 4cyl, as for showing up suddenly I haven't had this boat out for several years. I have cleaned the carbs new fuel lines, new 13p prop and plugs. I have tested spark and all checks out did voltages with my DVA and Everthing seems good, also I did change water pump expelled. Could I not have something together right?