250 HPDI Restricted to 4600 RPM

Hello all,

Loss of top end. Normal WOT is 5600. What I've done:

-Plugs are clean
-Compression is 115-122 on all cylinders
-Racor replaced
-Engine mounted fuel filter replaced
-VST filter replaced and the VST was totally clean

And I've almost exhausted my outboard mechanic skill level.

I "heard" that the low psi fuel pumps can cause this, but before I buy them I wanted to see if anyone out there agrees through experience.

So, does anyone?

[boats.net]

Yes need to check fuel system, low pressure pumps, VST fuel pressure and high pressure fuel pump pressure. Would need to it connected to computer diagostic to check high fuel pressure and check for faults.

[Mdelgado]

Greg, how did you make out? I'm having a similar issue with my 300 HPDI

[Tucker]

I'm reading lots about these LP fuel pumps going bad. I thought the HPDI was Yamaha's best motor. Why are these LP fuel pumps the weak link?