2000 200 HPDI problems

[mrv8outboard]

I have a 200 HPDI that accelerates fine out of the hole up to 3500 rpm's after that the more throttle just flattens it out, pull the throttle back some and it picks up. there is 18 hrs on all new racor primary, paper primary in the plastic bowl on the block, yellow strainer on the vst, and metal inline from vst to high pressure pump. No codes and the software states "normal" on fuel pressure. I put a vacuum gauge just before the plastic filter on the block and get no vacuum thru the rpm range. Then a pressure gauge between the lift pumps and the vst with a reading at low rpm 3-3.5 psi at wot 5 psi. Then tested the output at the vst is 51 psi. I am thinking high pressure pump but that would mean both the pump and sensor would be bad because the software is saying "normal"

Any incite would be helpful.

Thank You

[boats.net]

Did you run fuel test while running at 3500 rpm's?

[mrv8outboard]

Every thing I stated in my post were at 3500 and the throttle to the full position and back to match the 3500. 0 in/vac and no air bubbles in the clear section of line, 5 psi at the lift pumps (3.5-4 at idle and just off idle), 51 psi at the VST, and the software states "normal" for high pressure.

[mrv8outboard]

There was like five responses to my post last night, then not a one this afternoon until yours. Did the data base get reset?

Thank you

[boats.net]

It sounds like a fuel problem but if all test are good then clean and test O2 sensor.

[mrv8outboard]

I have replaced the strainer between the VST and the high pressure pump. That has helped a lot. New question is were does the Yamaha software get the low pressure input from?

[mrv8outboard]

The paper element in the strainer between VST and high pressure pump was plugged and replacing helped. I have now replaced all of the filters and found the filter in the VST was plugged as well. The paper engine mounted one was not as well as the water separator on the boat was ok, but all have been changed. I will water test and get back to you all.

[mrv8outboard]

Well it has been a while but after the water test the motor ran fine up to WOT but on the software there was still a drop in high pressure to just below spec. That was then, now the issue is back changed all the filters and ran a pint of SeaFoam mixed 50/50 with gas through it. Still have low high pressure. Is there any screens or filters in the HP pump that I should focus on next. Otherwise it is going to need a 1292.68 list 988.40 cost replacement pump.

[boats.net]

Flagship Marine Engines can rebuild the high pressure pumps

www.flagshipengine.com
There is filters inside pump but are not replaceable unless you have it rebuilt.