Rpm issue on hpdi's

[Cobia270]

Hey guys I have twin 2001 200 hpdi's. Put the boat in the water today after a long winter. Winter maintenance included new vst filter,new plugs, new fuel filter and water separator, new water pumps,and new low pressure pumps. The only filter I didn't change was the canister filter above vst. Boat got up to 3300 rpms smoothly the second the tried to push it my port engine wouldn't climb and in fact it dropped rpms until I let off the throttle. Give it throttle again and it runs smoothly til 3300. Any ideas?

[gunz@pc]

may sound funny but....

K had the same issue a few weeks ago got to 3500 rpm (YDIS all good) and then no higher, went back pulled the plugs looked fine but had some extra so put them in and now good to go WOT like new. Hope it helps>

[Cobia270]

I changed the plugs when I got back to the dock and took her back out to the same problem. Is it possible one of the lp pumps were no good?

[gunz@pc]

Maybe but once it goes from the LP side it goes to the hi pressure pump. I saw about 40 to 44 psi when I hooked up my gauge to the VST schrader valve. Then when I hooked up the YDIS I checked the HP side and was getting about 680- 702 psi. One thing on friends engine that went wrong was his shift switch was not letting his other 2 non firing cylinders kick in when it went into gear. VST screens can get really clogged and Mr Rodbolt has a great way to clean, might want to do a search on that. But basically you take the VST drain out get some carb cleaner bend to straw upwards put it in the hole and give her a squirt. Other problems we have had are clogged Fuel injectors. Good luck hope she gets better.

[Cobia270]

Thanks but don't think it's vst filter since I changed it with my spring tune up

[Cobia270]

Rodbolt any ideas?

[Cobia270]

Spoke to a mechanic today who thought it could be a shifter switch. Any thoughts?

[Pbailey15]

In not sure exactly what model you have, I had a very similar problem on a F90. Mine would cut out around 2500 as I recall. I too changed every filter, but then found what's called a strainer on tne parts breakdown inline between the low pressure and high pressure pump.

It was clogged and changing it fixed the problem. Not sure if your model has it. A little difficult to see on mine. Inline and under a holder.

[Cobia270]

Went to the boat today and changed out the strainer with no change. Does anyone know at what rpm the 5th and 6th cylinders are supposed to kick in?

[rodbolt17]

why oh why would someone NOT change the medium pressure filter.
that's the one between the VST and the HP.

if the shift position switch tell the ECU its in N the ECU shuts down cyl 2,3.

if the switch tells the ECU its in N and the ECU sees the RPM above about1500 it also shuts off cyl 5&6..
if the ECU sees an in gear signal when started it limits the RPM to about 2300.

its a rather unsophisticated ON or freaking OFF switch.
simple to test easier just to watch it on YDS.
its either ON or its OFF.

a quick run with YDS can show switch operation AND HP rail pressure.
gotta test it at the FAILURE RPM and load.

no other way.

[Cobia270]

The only reason I didn't originally change the medium pressure filter was because I changed it last year and only put on about 40hours with it. So the bottom line is I can't do anything else til I get a computer on it?

[Cobia270]

Does anyone know the location of the shift position switch ? I'm still at least a week away before I can someone to put a computer on it.