Honda BF15 15HP outboard dies at full throttle

[codybadger]

Hi all, I'm new to the forum. Hoping to get some help here:

I've just acquired a honda BF15 motor for use on my 14' RHIB. I went out crabbing for the first time this weekend, and the motor dies at full throttle. It idles fine, ran all day at lower speeds, but whenever we sustained full throttle for over 30-60 seconds, the motor would lose almost all of its power. It would stay on, and surge a little bit at a very low level. It would either idle after that or just shut off. If it was idling and we gassed it, it would die instantly, but it'd restart on the first pull, have no memory of power loss, and go up to full throttle again.

I'm no expert, but this feels like a computer control issue to me - shutting the motor off resets something. Could it be overheating? I could be totally off here. Would love some insight. Thanks.

Here is a photo of the motor running and the cooling water exiting the motor at full throttle:

 

[ahicks]

My bet is that it's running out of fuel when it needs anything over a just trickle. It can't get the necessary fuel flow rate to run beyond a certain throttle setting.
Usual suspects, in no order-
Fuel line sucking air - could be loose at either end (look for fuel stains), or the pick up tube in the tank may be cracked/broken
Fuel line collapsing internally- these new emissions type hoses don't have a real good reputation, not REAL unusual.
Fuel pickup screen in tank plugged
Fuel tank vent not open or plugged somehow - generally will collapse the primer bulb.
Plugged fuel filter

 

[MattFL]

I agree completely with the above, it definitely sounds like it's starving for fuel.

 

[km1125]

Have you tried pumping the primer bulb when you first get symptoms? That could tell a lot by how it responds.

 

[Sea Rider]

Old gray fuel hoses used to have an internal second sleeve which deteriorated over time in small pieces and partially clogged the hose when more fuel intake was in demand, check if it's a single or double sleeved fuel hose. Been there and that sucker nearly drove me insane till the culprit was found...

Happy Boating​

 

[codybadger]

Have you tried pumping the primer bulb when you first get symptoms? That could tell a lot by how it responds.

Yeah. We had the same result when pumping or not pumping the bulb when this would happen.

 

[ahicks]

Yeah. We had the same result when pumping or not pumping the bulb when this would happen.

That might point to a partially/mostly plugged fuel filter.

 

[raczekp1]

this motor have overheat sensor located in Left hand of the head. if vater pump is not working well or thermostat is fully close than sensor will activated. and cdi will go to limp mode on higher rpm

 

[codybadger]

update: so i brought my motor to a shop, we ran it from his fuel tank and line, and it ran fine at full throttle in forward.

 

[ahicks]

Glad you found the issue, and thanks much for getting back with us so that all can possibly learn something from your experience. -Al

 

[Sea Rider]

update: so i brought my motor to a shop, we ran it from his fuel tank and line, and it ran fine at full throttle in forward.

Was the motor run with a special test prop in a deep water tank at full throttle in forward gear ? If the hose was the cukprit get a new fuel line and test the combo at open water at full throttle and check if misses or not.

Happy Boating​