1990 OMC Cobra 4.3 Starts Missing After Warmed Up

[Weekend Work]

I have a 1990 Four Winns Freedom 190 with an OMC 4.3 L IO. Last year I noticed that the engine would start missing when I applied the Trim Switch when coming out of the hole. So, recently I looked inside the shifter to make sure there were no chafed or broken wires and found that everything seemed to test out fine. Then I went through and cleaned the battery, alternator and coil terminals. Unfortunately the problem still persists. Most recently when I put the boat in the water it ran fine from one end of the lake to the other which is about 15-20 minutes each way. Then we stopped at the marina for lunch. When leaving the marina I noticed this problem had returned. And as the day went on it appeared to get worse and even started happening whenever I went over 3000RPMs. It seems to be something that is impacted by heat as the longer I run it on a given day the worse it gets. Even later in the day it runs fine below 3000, but if you bump the trim it causes the engine to miss. I am thinking the coil may be on the way out, but I am looking for suggestions.

 

[alldodge]

appeared to get worse and even started happening whenever I went over 3000RPMs. It seems to be something that is impacted by heat as the longer I run it on a given day the worse it gets. Even later in the day it runs fine below 3000, but if you bump the trim it causes the engine to miss

I think your running lean. Has the fuel filter been changed, and take it off and see if its full. Pour the contents of the filter into something clear like a baggie or jar. If all looks good, place a fuel gauge inline between pump and carb to see if your getting 4 to 7 psi throughout the rpm range

 

[bruceb58]

If you have a miss when applying the trim switch, you have a bad connection which causes a voltage drop when you turned on the trim. Take all the wires off the starter and clean them to shiny metal.

I had the exact same issue and I ended up having a loose connection down at the starter.

 

[Weekend Work]

Thanks for the advice. I will dig into it in the next day or two to see if either of these pans out.