I have a 2004 Optimax 250 Mercury on a jet pump in a seadoo utopia. I had a huge problem last year and thought I should share the fix, which came a full year later. So after my daughter ran the boat out of gas in June 2015 the local on-lake marina charged me $2,500 to get it going, replacing lines, pumps, belt, battery, filters, etc. When I took the boat back it immediately had an issue, hesitating and cutting out at high rpm. Once the sputtering started, it would continue at any rpm above 2,000. I took it back within minutes. They chased the problem, adding $2,000 in repairs replacing the compressor, cleaning the VST, etc. Nothing worked. Finally in September 2015 I took the boat back angry. Marina would not give me any sort of discount, etc. even though $3K was labor. In any event, I took the boat home and stored for the Winter. In Spring 2016 I took the boat to a large local dealer with reputable mercury mechanics. They got the boat running perfectly, but they too had a little trouble finding the problem, so I figured it made sense to post it here for others.

It turned out that the original mechanic did not do all the work he said he did, including the filters and tensioner spring, which prompted this mechanic to start over, from scratch with testing, etc. He found that the pickup pump was running at 10 volts, but at higher rpms (in the water under stress) it would drop to 0 volts. When replaced, the boat ran great to 4,500 rpm but then sputtered above that speed. The mechanic noted that the VST was dirty and that the original mechanic did not clean it out. He order a kit and cleaned it out, replacing the small parts, assuming reeds, and filter, etc. Once that was completed the boat ran perfectly to 56 mph. Its perfect now. All in, the boat has new pumps (3), lines, filters, belt, battery, tensioner, air compressor, some sensors, regulator, coils, etc. I have $6K in repairs, which still beats a new $45K jet, but not by much!