Update on 1993 4.3L v6 not running right

[kulle]

HIstory:

Purchased a 1993 Sea Ray 180 w/ 4.3 Merc 2bbl. Boat ran great first time out. Second time out it kept stalling to the point I could not restart. Tested again in driveway and boat would only run for a bout 45 secs at a time. Took boat to shop, they replace water/fuel sep and oil pressure switch. Boat ran great on muffs idle and some throttle. Took out to water, stalled out on full throttle almost right away, would restart but hard, then stalled again and would not start. I started to replace items out of frustration, replaced ign coil, distributor sensor ( and rotor-since i broke it) and cleaned dist cap ( wasnt bad) and noticed my batt neg was loose! took her out and was able to run her for a good 20 mins on/off full throttle, then she stalled.Was able to immediately restart and cruise more...then once more it stalled..same thing, easily start back up - didnt need a tow this.
time..ran much better but still seems something is grounding?

when it shuts off, its like someone turned the key off or pulled kill swtich ( i dont have one) - not like its running out of fuel...sounds like a short somewhere on a exposed wire? could the neutral safety switch cause this or is that more so for in/out of gear?

 

[Scott Danforth]

First, prior to spending any money, clean every connection from the battery to the motor and back. By clean, i mean take scotchbright pads and clean to shiny metal.

this includes the connection to the block. If any cables are green, crunchy or stiff, replace them

Also clean every connection from your starter post to the big circuit breaker, to the harness plug, ignition switch, safety lanyard switch and back.

This also means cleaning the ground buss under the helm

Then use marine electrical varnish to seal the connections

Also, it is never the coil. Only about 3 out of a million coils changed were actually bad

 

[Scott Danforth]

Also, with any new to you used boat, take the time to do all the maintenance. Oil change, fuel filter change, pull the drive, do a bellows replacement. Inspect the alignment, gimble bearing and u-joints. Do a full raw water pump change.

 

[kulle]

Is the pump in the lower housing where the water is sucked in the intakes?

 

[Bondo]

Ayuh,..... It sure would be nice if you quit startin' new threads 'bout gettin' this motor runnin' right,.....

Yer missin' a huge chunk of the history of this issue, many points of which have been already covered,....

This link goes to all 7 threads you've started, 5 of which are directly related to this thread,....,....
There's just to many to merge together,.....