'85 115 hp OMC 2BBLC Cross Flow High Speed cut out

[Auxlarry]

Took the boat out yesterday for a great day on the water in Tampa Bay and started having an issue after about a half hour of run.
Had been running great at WOT, 5700 RPM and charging around 14.2 volts when all of a sudden it started slowing down and felt like it was running on 2 cylinders. i noticed at that time that my tach was around 6100 rpm (even though I was slowing) and my voltage was around 12.2 volts.
Checked my fuel bulb and it looked good and pumped but it made no difference and I tried choking and it made no difference except it felt like it was flooding when choked.
Ran this way for about a minute and then it started picking up again, came up on plane and then it bogged down again.
Limped my way back to the dock and took the hour drive back home.
when I looked into it at home it fired right up, ran and idled normal.
Checked the plugs and they were a beautiful tan color, checked spark at over 7/16" and checked compression.
#1 115 psi, #2 118 psi, #3 115 psi, #4 118 psi
Fuel system is new from a cleaned tank to a new fuel filter/seperator. New lines and new pump (run premix), carbs have been rebuilt.
I think I have ruled out fuel issues but can I be having a problem with an electrical breakdown when parts get hot? I did a quick ring out of my stator, timer, and packs and they ohm out per cdi but that was a cold test. Could a stator or regulator cause my tach/voltage/run issue?

Larry

 

[emdsapmgr]

Re: '85 115 hp OMC 2BBLC Cross Flow High Speed cut out

Probably easiest to check the spark first. You are right, weak ignition components tend to fail when they heat up to normal operating temps. I'd run the engine with a friend till it warms up and starts to slow. When the engine starts to slow down, remove the cowling and put an inductive timing light on each of the 4 plugwires. Run the engine under load. The flashes in the gun will tell you what is going on with the ignition/spark. You do have two, identical power packs on that engine. If one side (head) loses spark, you can swap those packs and see what happens. If you still have solid spark and the engine has still slowed, I'd start looking at the fuel system. Your engine will charge high when first started, then the voltage will taper off-a normal thing once the battery recharges. Usually when the combination regulator/rectifier starts to go, not only does the voltage act up, but typically the tach will also start to read funny. Based on your comments, you may have a problem with it. I'd get the engine slowdown issue addressed, then get into the charging issue. Since the engine ignition runs on it's own power, the only time you use the battery is for starting. It will take a long time to run the battery down on that engine even if the charging side is non-functional.