1988 3.7 4 CYL MERCRUISER BOGS OUT

[OTOOLBOX]

I HAVE A PROBLEM KEEPING MY BOAT RUNNING. I HAVE A 1988 3.7 165HP 4CYL MERCRUISER THAT DOESN'T SEEM TO IDLE VERY WELL AND WHEN YOU PUT IT IN THE WATER IT RUNS GREAT FOR ABOUT 1/2 HOUR AND THEN STARTS TO SPUTTER AND LOSE POWER UNTIL IT FINALLY CUTS OFF. IF I LET IT SIT FOR A WHILE IT WILL RUN GOOD FOR A LITTLE WHILE AND THEN START TO LOSE POWER AGAIN. IT DID LOOK LIKE I HAD A LITTLE GAS IN WITH THE WATER WHEN I PULLED MY PLUG OUT. ANY ADVICE? VERY FRUSTRATING. BOAT RUNS GREAT IN THE DRIVEWAY.

 

[boatguy19]

Re: 1988 3.7 4 CYL MERCRUISER BOGS OUT

check your coil, may be going bad

 

[MrBill]

Re: 1988 3.7 4 CYL MERCRUISER BOGS OUT

I would dismiss problem fuel as the root cause. In over 90% of problems like you describe are related to ignition issues. If you still have the original igniton with points, rotor and condenser, take note of how new the cap, rotor, points, etc are. As boat guy1 pointed out, the coil may be problematic, but I would start at the distributor, a hairline crack in the cap, or wear in the cap or rotor would cause the problem you described. Some diagnostic equipment, if available, could head you further in the right direction.

 

[achris]

Re: 1988 3.7 4 CYL MERCRUISER BOGS OUT

Had a similar problem on my 1994 4.3LX when I first bought it. Turned out to be a bad ground between the distributor body and the engine. As the dissy heated up the 'connection' became resistive and changed the baseline for the ingition electronics, knocked 6 degrees off the advance. Fixed it with a wire from the dissy body to the engine block. Was a ***** to find though.