After enjoying most of the summer problem free boating, this morning reminded me of the joys of boating – problems 20 miles from the boat ramp. I have an Indmar 454 w/Berkley jet drive. After running for about 45 minutes at 3800-4000 RPM, my engine began backfiring, very sporadic, and only at 3900 rpms and above.
I shut down in the lake, couldn't find anything loose, distributor tight & vacuum. Started it back up and again, only at high rmps would it begin, and again only sporadic.
If I attempted to take off (full throttle), it backfired badly so I backed down and slowly accelerated up to a smooth ride. As long as I kept under 3900 rpm's no problems.
Any idea & thanks up front and appreciate your thoughts!
propless