Background: bought a leftover "NEW" 2002, never started or had battery in it. Found out was manufactured in Aug 2001. Its a Caravelle with a 4.3L Carbed V6 Mercruiser, Electric Fuel pump, prety standard. Test drove at dealers, ran fine on limited trip. Stopped on way home and filled up tank with regular gas, 21 gals/30. Took to Lake and went out, about 45min, no problem, Next day, hot July 4th, tubed for about 45 minutes, had some problems with dieseling, immediately turned back on, idled down and turned off, Mercruiser bulletin 97 on this problem, ok.<br />Evening tubing, about 45 minutes-hr, powered down to enter docking area about 500' of no wake started running real rough, shaking boat at about <1000rpms, finally quit, hard starting, got it started and went back out to good water and higher idle running rough, opened it up and at 1500 rpms ran fine and planed great cruised at 3000rpms... came back to cove, <1000rpms rough again parked into slip. Next morning, couldn't get to start at all, sputtering and backfired. Towed 90 miles to dealer. Mechanic hooked up to water ears and started right up. I think he had it at 1/4 throttle cause he powered back quickly. I have never started my 260 at 1/4 throttle but it was old and mechanical fuel pump.<br />Whew... well he could not duplicate the problem except dieseling which he adjusted the carb. didn't know about merc bulletin. Took back home 90 miles. Took out and on first start at idle shifter, no go, 1/4 throttle setting and started up and ran ok, but now TACH is floating and mostly pegged at bottom. Still ran good on 5 mile trip to fishing hole. Fished for awhile on trolling motor, Started up ok then after 30 seconds trolling "No Wake" started doing it again, sputtering and wheezing, increased rpms to ? and it ran fine, back at idle shaking... got out to good water and opened up 3/4 throttle and planed in 4 seconds and ran great. Returning to dock did ok again on limited idle time. TACH still not working.<br /><br />Anyone have any IDEAS!!! Loose connection? Bad gas? <br /><br />Thanks!
