4.3 L merc cutting out

[Keith Turner]

I have a 1989 Sea Ray Seville w a 4.3L merc .
After about 30 min of half throttle cruising the motor start Running rough, backfires and cut out. After about 30 min of letting it cool down it starts and repeats the Rough idle and won’t idle and cuts out again . I wait another 30 min and it starts up . Same issue since last fall , having a hard time finding the problem .
Please let me know what you think it is . my gf Wong go back on boat till it is fixed .
Thanks

 

[Keith Turner]

Need some help

 

[Espos4]

I have a 1989 Sea Ray Seville w a 4.3L merc .
After about 30 min of half throttle cruising the motor start Running rough, backfires and cut out. After about 30 min of letting it cool down it starts and repeats the Rough idle and won’t idle and cuts out again . I wait another 30 min and it starts up . Same issue since last fall , having a hard time finding the problem .
Please let me know what you think it is . my gf Wong go back on boat till it is fixed .
Thanks

What have you replaced so far in your attempts to fix it?

 

[Garintheair]

Need some help

Fuel or ignition typically however, as stated above, what have you tried so far? It could be as simple as a slug of water in your fuel tank although if the cutout is consistent with run time/heat I would start elsewhere.

I think that your year engine has a mechanical fuel pump and Thunderbolt IV ignition module mounted to the riser? If so I would probably rule out fuel pump and concentrate on the ignition module (heating up and cutting out?) or pickup coil in the distributor. The module was moved from the riser to the back of the distributor, with heat sink compound, at some point to better protect it. Maybe coil heating up and dropping out, too?

Just some food for thought.

 

[Keith Turner]

I have replaced the fuel pump and the coil but still no luck

 

[Keith Turner]

Thanks will check out ignition module. It has a mechanical fuel pump