Mercruiser 6.2L MPI issues!!

[kswallac]

Good evening all,

This is my first post on here so please excuse my lack of knowledge. I need to mention I am mechanically inclined but fairly new to boat repairs.

While coming in from a 45 minute cruise going about 3200 rpm the engine began to "jerk and sputter", resulting in sporatic acceleration and deceleration. I brought it down to idle and it seemed to run fine. When I attempted to speed up above 1500 rpm it would begin to sputter again. It also makes a knocking/clacking noise at higher rpms. I checked the gauges and everything is OK; temp, oil pressure, etc. Since I hadn't run it in about a month, I assumed condensation had built up in the fuel tank so I changed the fuel filter/separator and added Stable to the fuel. At idle it purrs like a kitten but as soon as I attempt to get on plane it knocks and sputters.

Any assistance/guidance/suggestions is much appreciated. As I mentioned, I'm not boat engine savy so please excuse my ignorance.

The boat is a 2004 Sea Ray 270 Sundeck with the 6.2L MPI with Bravo III outdrive. Up to this point I've never had any engine issues.

 

[mikemce]

Sorry this is not a solution, but I'm experiencing an identical issue with the same motor in a 2006 270 SunDeck!

My dealer suggested changing the fuel filter, so I'll do that tomorrow and let you know if it helps. Please post any answers you get.

Thanks.
mikemce

 

[AAK]

Just a guess but it could be fouled plugs if you are lucky but most likely it's a fuel issue. I think your 6.2L has the fuel cooler unit (looks like a black lunch box attached to the side of the engine) on it and it has a low speed fuel pump, a high speed fuel pump along with a paper fuel filter cartridge. If so it could be a bad high speed fuel pump or a clogged filter. A lot of people tend to neglect this filter since it runs about $40 for the part. Somebody should jump in to verify this if I remember correctly. I just thought I would throw this out to give you something to check out.

 

[jason78]

Just a guess but it could be fouled plugs if you are lucky but most likely it's a fuel issue. I think your 6.2L has the fuel cooler unit (looks like a black lunch box attached to the side of the engine) on it and it has a low speed fuel pump, a high speed fuel pump along with a paper fuel filter cartridge. If so it could be a bad high speed fuel pump or a clogged filter. A lot of people tend to neglect this filter since it runs about $40 for the part. Somebody should jump in to verify this if I remember correctly. I just thought I would throw this out to give you something to check out.

If it is a Gen 3 Cool Fuel which I feel could be, (especially for the 2006 guy) there are actually two filters to worry about in the cool fuel unit if it is indeed the fuel filters causing your problem.

See thread http://clubsearay.com/forum/showthread.php?t=27133&highlight=cool for more info.

If not you will have a Water Seperating (OIL Filter Style) Fuel Filter and a smaller inline filter. You will need to figure out which filter system you have.

 

[mikemce]

Thanks to AAK and Jason78 (especially the link to the filter change instructions!).
My 2007 270SD with the MX 6.2l MPI does have the GenIII cool fuel module. I changed both filters yesterday. Both were dirty with a little debris and noticible water. I was unable to take the boat out until this morning.
After my 1+ mile of idle zone, I opened it up. It hesitated slightly, but came on strong. I ended up runnng around for about an hour; slowing down, then WOT, then 3000rpm cruise, etc.
I think this is a fix.
However, I'm getting some spare filters in case I have some water in my tank that could clog the filters again.
Would it help to add Stabil to the gas? I've got about 50 gallons in an 85 gallon tank.