I have a 1995 sea ray ec 215 with the merc 5.7L. that seems to be running on only 4 cylinders. Some back story of my problem....The engine has run fine for the past 5 years. I have kept up on regular maintenance. When I started the engine Saturday morning it ran as good as always. For the next 45 minutes or so we were cruising at about 3400-3500 rpm and then decided to do some floating for about an hour. Again I started the engine and it ran fine. We got back to speed for another 20 minutes and that's when the problem began. I came off plane and noticed the engine was definitely not running like normal. It felt as if a cylinder was not firing, the rpms seemed lower than normal, and sounded like it wanted to stall. I could throttle up and it seemed to run better but still not normal. We spent a few hours at the beach we were going to and then headed home. I started the engine and it continued to run in the same manor at idle, but did not seem to have any problem getting on plane and we cruised at 3400 for the next hour no issue, but back at idle it still ran bad. Fast forward to today. I have changed the fuel/water separator. I emptied the old one and there isnt any water and hardly any debris. I also changed the spark plugs as they were due. I started the engine, no change, the problem was not fixed. I did a test at the distributor, pulling different wires off the cap to see if there was any change in engine sound. I discovered that every other wire in the firing order could be removed without any effect. Pulling any of the other wires caused it to stall. In fact, I removed the 4 "non firing" plug wires from the distributor cap at the same time and the engine ran exactly the same. The cylinders not firing are 8, 3, 5, and 2.
What would cause half the cylinders not to fire in an every other pattern on the distributor? Could the ignition interrupt switch be grounded, causing 4 cylinders to not fire (I thought it cut spark to all cylinders)? Is the ignition control module bad, or the distributor sensor?
What would cause half the cylinders not to fire in an every other pattern on the distributor? Could the ignition interrupt switch be grounded, causing 4 cylinders to not fire (I thought it cut spark to all cylinders)? Is the ignition control module bad, or the distributor sensor?