mercruiser 305 5.0

[midnightrider1818]

ok fellas. just purchased a 89 Larson 215 sport cruiser. ive already fixed a few issues and onto the last one. the problem is according to tach. not sure how accurate once you get up to around 37 3800 rpm it just falls on its face. bogs down. you back out of her a hair runs smooth as a sewing machine. I have not done anything yet to it. changed filter or nothing. I was gonna hook a light up to it and check timing. calls for 5 degrees advanced. I was gonna also make sure it is advancing. not sure when its supposed to be at full advanced or what rpm that occurs at. I am however leaning towards fuel problem. it does not backfire just sputters. its got the 4bbl on it. not sure even if the secondarys are coming in. I did however look and at full throttle the secondary plates are opening. the bottom plates of carb. right now choke plate is closed which I believe it should be as engine is cold. just wondering if anybody has had this happen and if any of you sea mates have any pointers on this issue. I live in northern ohio so winterizing is coming very soon. just wanted to see if I could get this issue addressed before I put emma jean up for the winter.

 

[achris]

Merc's been using 305s since 1977. It would help us immensely if you told us the year, and the engine serial number. (boat year doesn't necessarily mean engine year. Just look at my boat and engine)

Chris................

 

[alldodge]

I would look at the fuel system and check pressure, should be 3 to 7 psi.

 

[wellcraft-classic210]

Yeah-- fuel restriction is likely

 

[kenny nunez]

When you test the fuel pressure as A D posted remove the inlet fitting and check the filter.

 

[Rick Stephens]

My take is a plugged up carburetor. That you get back to power by reducing throttle is dead indicator of plugged up carb. Rebuild it. Pay particular attention to float height. Be crazy anal about cleaning every passageway and getting that float height perfect.