Mercruiser 350 MAG MPI Problems
So a few weeks ago I was on my 2005 Chaparral Signature 240 equipped with a Mercruiser 350 MAG MPI with a Bravo Stern drive. I used the boat only about a dozen times during the season and was heading to have the boat winterized. I was heading from Brooklyn, NY to Jersey, City crusing at about ~ 22 Knots against the current running the engine around 3400 RPM when I realized I had broken the rule about having enough fuel as I started my trip with what appeared to be a bit under a quarter tank of gas on my 70 gallon tank. While heading towards the Jersey City marina fuel station I realized I overshot the channel markers and promptly put the throttle into neutral, the boat lurched and then the engine cut off. I tried to start the engine a few times but it would cut off soon after starting. I had assumed I ran out of gas and was lucky to find a passing trawler that held me in place until a passing Coast Guard vessel towed me into the fuel dock. After filling up with gas, I started up the engine and sighed a breath of relief but then soon after my engine cut out again. I opened the engine compartment to find that the engine belt had slipped off the engine. I was a bit perplexed by this as this had never occured and with some help I was able to get the belt back on. I started the engine again and it
seemed to be ok but after about a minute it cut out again. An employee at the fuel dock suggested perhaps the issue was fuel related and recommended I add some Star Brite Star Tron Gasoline Additive. I did this waited about 15 minutes and when I started up the engine, still it run for about 45 seconds to a minute then it stalled. Another boat owner suggested there could be a problem with the fuel filter. So I went ahead and replaced the fuel filter and I noticed the old fuel filter was a bit dirty. This time when I started the engine it would run idle for an indefinite period of time but whenever I applied throttle above 1200 RPM then engine would shortly cut out. I had the boat towed to the mechanic who told me one of the fuel pumps was showing low pressure. He replaced both fuel pumps and although I was told my fuel pump pressure is ok, the engine keeps cutting out. He used a Rinda MerCruiser Scan Tool to check the engine but says its not reporting any faults. I was then told it could be the ignition coil and spark plugs so they too were replaced but the end result is that the engine appears to run fine on idle for an indefinite period of time but when throttle is applied for more than a minute or two the engine cuts off. The mechanic has a case open with Mercury but any suggestions out there? Anyone run into a similar sitation?