Two Motor Issues

[rrichar1]

I have two boats with two issues.

1. My fathers 1982 Wellcraft 18 Fisherman / 1989 Johnson 120 HP. It has had a ring job, fuel pump, cleaned carburetor and maybe more. It runs fine at idle on ear muffs. I take it to the water and for the first 15-30 minutes in the water it runs great but then it stalls/dies and I can get it started a couple of times but it eventually dies and will not restart. We patched a leaky fuel tank but now think that it may have a leak in the fuel hose as the bulb will not get hard and stay hard. Our next test will be to put it back on an external portable fuel tank. Our first time out we ran it on the external fuel tank for a short 30 minute test trip and it did not stall but it was not a lengthy (time and distance) trip. Anybody have any ideas?

2. My Alumacraft Fish and Ski boat. I have a 1996 Nissan 90 HP motor that runs great from 1000 RPM up but from 1-1000 RPM the engine overheat (?) alarm will ring and only go off at 1000+ RPM. I haven't changed the impeller in a few years and will do that shortly but I also think it could be the thermostat (original, that I know of) or slightly clogged water jacket / coolling passages. Any idea on this?

Thanks for any suggestions.

Ron