Honda 15hp stop and surge issue

[odes20]

Not sure if this is a limp home mode override, but having bought this 2009 model BF 15 recently, I test run it and it runs beautifully but if I then run it up above 3/4 or full throttle for a bit, it shuts down, to idle, surges about 4 times and then stops. It then starts first pull straight away, and runs perfectly till the same issue happens again.

I have replaced impellor which was old and breaking before I tested, then after first test I removed the thermostat which looked pretty forlorn as well. I was thinking of testing it again this arvo and when the prob occurs, I might disconnect the temp sensor and run it just to see if it is faulty or whether its a heat related issue. Having said that the motor doesn't seem to be hot at all when it occurs, and as mentioned starts up immediately and powers away for quite a time before the issue occurs again.
Any ideas or experiences appreciated.

Thanks. John

[TheRealPoMo]

Fuel line or tank breather issue?

[Fed]

Sounds like its running out of fuel, check for fuel restrictions and tank venting.

What pomo said.

[odes20]

Took it down this arvo and ran it again. Once again stopped about a minute and a half after accelerating to full throttle. Disconnected temp sensor, and ran without stopping at all. Re connected sensor and it repeated the problem. So im thinking the sensor could be at fault as the motor seemed no hotter to touch after a longer run without sensor connected, not that I could detect anyway.

[Spaniard_King]

You Have a blockage in the cooling water system

Possibly under the power head or in the cylinder head Itself, this usually occurs when it is not flushed properly

[odes20]

So Gary the head will have to come off? New head gasket?

[Spaniard_King]

yes new head gasket and exhaust cover plate gasket

[odes20]

Thanks Garry
Ill get it sorted

[odes20]

We removed the Temp Sensor and found a blockage was gunked up not allowing the flow of water to surrond the sensor. After a little dig it freed with plenty of water flowing out of the sensor hole. Blew air down the same hole at strong pressure as well.

Then went out tested it extensively at WOT and general higher revs where the overide had shut it down before on a regular basis, and it never failed once. Complete water test was for over 30 minutes so im happy to see the prob resolved.