Engine running lean at high rpm ?

[sunnyboy]

Hello everyone, I have an 18ft boat, with V6 4.3L Mercruiser and noticed on the last two outings that at high rpm ( 5k RPM), I was getting what sounded like a muffled popping sound.

I rarely run the boat at 5k RPM for long, but we were in a hurry to get back to the marina.

Anyways... it sounded like.... pop.......4-5 seconds pass pass.......pop...pop........3-4 seconds pass........pop...............pop..pop............

It only happens at 5k RPM.

I videotaped it the engine on the water at 5k rpm and have the sound. When I played the video back, with the engine cover off, it sounded more like the engine was missing, or leaning out.

I purchased a new fuel filter and Mercury Dri-Fuel, to rule out any water in the fuel.

Anyways, I will be installing the new fuel filter and putting the above additive in to see if that helps.

I figured, it was the cheapest place to start.

After consulting with my father, who knows engines, his thoughts are that the "popping" sound may be indicative of the engine missing, or leaning out at high rpm.

If the fuel filter gas treatment doesn't work, I think our next step will be to look at the carb.

[Slough]

A rev limiter will make a carbed engine miss. Has it always done this or just started?