1987 340 MERCRUISER 454 CU IN

[B BARKER]

Cruised for about 1 hour at 1800-2000 rpm stopped was throwing anchor out and port engine quit. Tried to restart and it would not fire, then it backfired through the exhaust enough to blow a hole in the top of the muffler !!! After it cooled down it would crank and idle but when you barely give it gas it quits....Next morning fired up and seemed to run fine sitting in the slip, any ideas anyone ?? It's been a while since she's had a tune up but it's been running fine starting fine etc....

 

[scoflaw]

start with a tune and if that's not it probably a valve issue.

 

[KEVIN D TOBIN]

Cruised for about 1 hour at 1800-2000 rpm stopped was throwing anchor out and port engine quit. Tried to restart and it would not fire, then it backfired through the exhaust enough to blow a hole in the top of the muffler !!! After it cooled down it would crank and idle but when you barely give it gas it quits....Next morning fired up and seemed to run fine sitting in the slip, any ideas anyone ?? It's been a while since she's had a tune up but it's been running fine starting fine etc....

is there any chance of water infultration from when you stopped to drop anchor ?

 

[km1125]

Definitely need to go over tune-up issues. A (or several) misfiring cylinders will cause raw gas-air mixture to end up in the exhaust and a late-firing cylinder will ignite it. Check mechanical advance too, to make sure it's operating correctly. After running at higher RPMs, it might be stuck in an 'advance' state and when you slow down it's TOO advanced.

 

[B BARKER]

Pulled the muffler and repaired it and took the Dist cap off there was a lot of corrosion on the inside of the Dist as the gasket was shot on the cap. The coil wire was corroded all to pieces, so I'm getting all the tune up parts together I think this may be my Major problem......

 

[km1125]

If there was ANY corrosion evident inside the distributor, then make sure any mechanical advance mechanism is also cleaned up and working properly before you finish inside there. Besides just making the mechanism stiff or intermittent, you can also rust a spring through and cause the advance to start WAY too early which would be VERY BAD for an engine under load.