Honda 150

I've got a 150 that starts and runs right up to about 3000rpms and than bells go off and it boggs down. It stays running with the alarm going but won't run back up untill you shut it off and restart. Than shortly after going passed 3000 rpms does it again. It runs all day with or without load under 3000 rpms. We've replaced exzuast heat sensor and both oil pressure sensors. Its got plenty of oil and is pumping water just fine. Its seems to got to default mode as to not tear up engine but can't find problem thats putting it in there. Any tips???????

Is it throwing any codes? That would be my first item. Try draining the HP fuel pump vapor separator and see if you have water or debris.

the code seems to be low oil pressure. Cold the engine runs for 10 - 15 minutes no problem but after warmed up it goes into default mode within a minute of exceeding 3000 rpm?

I hope it I am wrong. Remove air intake box on top of upper pully. On the STB. side is the crank possion sensor. See if the pully is not rubbing on it. If so then the crankshaft thrust bearing has failed. Or the optional test is the " PRY" test. Use very large screw driver or bar and GENTLEY attempt to lift pully.Manuf. spec for end play is 0.14. Good luck Thanks Martin

Sounds very very familiar...you can't miss it when youo see the flywheel dropped down and rubbing on that sensor! I tried the pry methos but it doesn't have to move much at all to indicate the failed crank thrust bearing...hope your luckier than i was.....