Low voltage on Yamaha 225 4 stroke 2004

[rib4charter]

I have been trying to fix my engine for a year now. My engine doesn't go above 3200 rpm. I can throttle up to 3/4 and then it just bogs down like it is fuel starved. First thing I checked was the fuel, no water, added Starbrite just to be sure. Changed the water seperator just to be sure, still the same problem. I bypassed the water seperator went straight to the main fuel line, same problem. Checked the filters on the engine, clean, but replaced anyways, still the same problem. The VST tank was corroded and replaced, worked for a day, then the same problem. The fuel pump was also replaced as it was shot with 930 hours on it, still the same problem. Compression checks out, fuel lines check out, I ran it off a separate tank still had the problem. I noticed the battery gauge was blinking and reading 11.8 then 11.4 as the engine spooled up. Could it be an electronic issue? Would low voltage at 11.4 cause the fuel pump not to build enough pressure at high RPM?

 

[rib4charter]

Re: Low voltage on Yamaha 225 4 stroke 2004

The mechanic has been looking at if for 4 days, still trying to diagnose, any thoughts?

 

[rodbolt]

Re: Low voltage on Yamaha 225 4 stroke 2004

first fix the charging system issue.
then test fuel rail pressure at the problem RPM.
then I would find a real tech.
never seen a shot HP pump unless water got it.
well maintaned 930 hours is barely broken in,poorly maintained and its about done.
and yes as both the ign system AND the fuel system require 12V to operate its possible thats your problem.
make sure your tech has school certificates from yamaha for 4 stroke systems,electrical systems and fuel systems, if its not on the wall leave.