115 Johnson Faststrike Problem

I have Johnson 155 hp Faststrike 1995. Starts great run great well until after running for awhile. I was on the river yesterday, I would be running at 5000 rpm, the horn would sound, motor drop to idle. One long horn that sticker says is overheating or fuel restriction.

Stop boat, turn off, fires right back up and runs great. Did this three times on a twenty minute run. On the way back ran all the way back without a problem.

I have replaced impeller, water pump, rebuilt carbs, replaced fuel lines and now I am stumped.The only difference is on the way back I did not push it past 4500 rpms. On the way down ran it at 5000 rpms.

Any ideas?

I had a 150 gt 1985 that at idle speed would sound horn before getting all the way thru a no wake zone,went thru same impeller etc.,turned out in my case to be a weak sensor.
Hopefully maybe someone knows.

possible fuel delivery problem.

don't know if this helps but got a 1998 115 fast strike and had the same problem and turned out I was low on oil in my automatic mixer. Just a solid beep.

[QUOTE=bassfish606;468811]don't know if this helps but got a 1998 115 fast strike and had the same problem and turned out I was low on oil in my automatic mixer. Just a solid beep.[/QUOTE]
that shouldnt be a solid beep...

thats what I thought also, but changed the water impeller, checked for bad fuel hose, and still didn't fix it, so I tried adding more oil (it was a little low) and that took care of the buzzer for me. That happen this spring and it hasn't happen since that. Just thought it may help out.