2013 yamaha 115 4 stroke outboard Power loss

[apqe4848]

Hi,

I have

2013 Yamaha 115 4stroke outboard power loss problems.


The engine always starts, idle and run at throttle under 3,000 rpm. It bogging down at higher throttle settings and would only run well again after throttling down for a minute or two. The longer I let it struggle at higher throttle the longer it takes to settle down again at lower throttle.

Fuel tank cleaned-ok,

injectors-ok,

fuel separator-ok,

fuel filters-ok

What could the problem be?

[99yam40]

restriction or sucking air on the suction side of lift pump would be my guess,
monitoring the pressure on the output side and vacuum on the suction side might show a restriction.
air leak would need to install a clean line to watch for bubbles during a test.

pressure relief valve sticking open might starve the VST at High RPM if recirculation too much fuel
just a thought