2000 HPDI 200's 900 hrs Low rev's

[Lizziejane]

These engines have been flawless for 900 hrs but about 20 hrs ago the stbd engine would start & idle OK, but not rev, in or out of gear to match the Port eng. After about 5 minutes at 1300 rpm (throttle had to be much further up on Stbd engine) The problem cleared and it ran fine all day. Both both engines run on same tank.
Had a independent, certified Yamaha mechanic do an annual in May, Plugs, Spin on & Water sep filters, water impellers. Coming back from the shop, Alarm sounded with good cooling stream visible, revs cut back on stbd Engine. I thought low fuel, or weed on intake, Let it sit and started up & ran OK back to slip (6 miles).
Happened again about 5 running hrs later. Cleared & ran fine 8 hours/offshore.
Refilled fuel tank, which had run low on last years fuel (used Stabil & Ring Free)
On the way back from fill up, Stbd engine would not rev. This did not clear this time. Mechanic is swamped and has not been able to get over to see boat at slip past 4 weeks (I have no trailer).
No water visible in filter.
I ordered parts for VST filter & downstream canister filter, all clamps and Diaprhram replacement for Low pressure fuel pump. Also Yam Diagnostic software. Per posts here I removed VST tanks. I have not put it back together yet, but the VST filter looked pretty clean to me. Not a spec in the VST tank after draining. Black crud came out the intake end of the canister filter. Hard to wash off hands.
Can anybody recommend anything else I should do/check/replace before reassembling? Can I check the pump in the VST tank with 12 volts across the red & blue leads safely?
Thanks!

 

[rodbolt]

Re: 2000 HPDI 200's 900 hrs Low rev's

clen the VST pump filter, replace the medium pressure inline filter use a CV clamp tool to properly set the new clamp.
use a standard automotive fuel rail pressure tester to test VST output pressure, should be between 45 and 50 PSI any time the pump is on.
this is standard maint, the VST and filters should be cleaned and inspected every 200 hours or YEARLY whichever occurs FIRST.
O2 sensor cleaning/TESTING is also evey 100 hours or so.
they typically dont make 200 hours.

 

[Lizziejane]

Re: 2000 HPDI 200's 900 hrs Low rev's

Thanks for the information, Rodbolt. Should I test the pump in the VST in any way before reassembling? I can do the pressure test off the Schrader valve, correct?
I guess I'm pretty overdue on these fuel filters. Hope that does the trick!

 

[Lizziejane]

Re: 2000 HPDI 200's 900 hrs Low rev's

As a wrap up, I put the new VST strainer on, even thought the old one looked pretty good. Changed both low pressure, diaphram pumps and changed the canister filter, downstream from the VST tank. Pressure at the VST valve was 50 lbs. Something worked. seems to be running / revving OK now. I will do a sea trial tomorrow. Thanks for the help!