Ok experts (non experts also very welcome) -<br /><br />One of my 1987 OMC 1.6L V4s acts like it is dropping a cylinder when under load. Starting seems normal - at wake speed in gear both motors seem normal - as I put the power to them to get up on a plane both are pretty much in sync up to about 1700 rpm. As they work hard to get up on a plane the port motor accelerates much more slowly than the stwbd. When up on a plane the port motor maxes out around 4300 rpm while the stwbd tops out at 5300 rpm.<br /><br />The water pressure guages for both motors read around 20 lbs and the teltale stream is strong for both (new impeller & thermostats within 6 mo). You can put your hands on the heads of the port motor at 4300 rpm and they feel normal (not hot).<br /><br />Back at the doc I pulled both plugs from the port motor and they all look the same & light tan. Recently I checked the spark to all 4 plugs and the spark was strong & healthy (plus new plugs & wires). I thoroughly cleaned & rebuilt the carbs on this motor also with no effect on the problem.<br /><br />Joe Reeves posted to an earlier simular problem with late model V6s due to an "anti siphon" valve. I'll check for this but doubt it as mine are twin V4s plus I think I have a single fuel pick-up from the tank - if this were it it would effect both motors.<br /><br />Any ideas on what it could be and how to troubleshoot it??
