Yamaha HPDI poor performance at WOT

[niklas63]

Hi everybody I have a problem with my Yamaha HPDI 200hp -01 that I hope someone can help me to solve.

I recently changed motor on my boat from a Mercury 200 EFI XRI -91 to this Yamaha HPDI 200hp. The Yamaha perform worse then the Mercury, I lost 5 knots with the change.

The motor feels strong up to approx. 4000rpm then it start to hesitate, I can?t rev it above 4500rpm.

I have the Yamaha Diagnostic system so I have checked the fault codes and there are none.

The O2 sensor readings doesn?t fluctuate at idle and it?s stable at ~0,8V and if I cover the no.1 throttle plate hole the value stays at ~0,8V.
When i run the boat the sensor measure 0,0v most of the time.
The motor perform exactly the same with the O2 sensor disconnected as connected.
I have swapped the O2 sensor 3 times and cleaned the housing ant tube but it act exactly the same.

At WOT the TPS reads 3,9V and 71,4deg is that ok?

Engine Monitor readings at WOT:

,Monitor Item,Result,Unit,
,Engine speed,4525,r/min,
,Fuel pressure (5.0?0.8),4.84,MPa,
,Fuel pressure (725?116),701.62,psi,
,Atmospheric pressure,1006.9,HPa,
,Atmospheric pressure,29.8,inHg,
,Ignition timing,BTDC 14,deg,
,Battery voltage (12-16),13.77,V,
,Oxygen sensor voltage (0-1.0),0.66,V,
,TPS voltage (0.5-4.5),3.90,V,
,Throttle valve opening (0-90),71.4,deg,
,Fuel injection duration,2.21,ms,
,Water temperature (below 90),53.5,?C,
,Water temperature (below 194),128.3,?F,
,Intake temperature (below 70),21.0,?C,
,Intake temperature (below 158),69.8,?F,

 

[niklas63]

Re: Yamaha HPDI poor performance at WOT

Does 3.9V sounds ok at WOT or is it to low?

 

[rodbolt]

Re: Yamaha HPDI poor performance at WOT

numbers look good, if the motor sat you may need to clean the injector screens.
on the O2 sensor check the sensor output with a digital multimeter.
if you are using the same prop from the merc check for gear ratio differences.

 

[niklas63]

Re: Yamaha HPDI poor performance at WOT

I checked the o2 sensor with both yds and digital multimeter with same result.

I have a prop with less pitch and with this prop it rev a littlebit more, around 5000rpm but it start to hesitate at 4000rpm just like the other prop.

I have tried to clean the injector screens by myself, no difference.

I have read about a screen in the high pressure pump could this one be clogged though the yds reads 700psi at wot?

 

[niklas63]

Re: Yamaha HPDI poor performance at WOT

I noticed that the vst o-ring is sealed with some kind of silicone looking sealant, could that foul the o2 sensor?

 

[ARCHSEA BUNKER]

Re: Yamaha HPDI poor performance at WOT

Get the proper o ring for the vst, when you have the thank open check the filter screen, dont expect to see a lot off crap, spray/soak screen with carb cleaner, there is also an acorn type filter on top of the vst tank cover that gets overlooked and caused me a lot of problems, its very small, mabey a quater inch wide. Get the manuel and it shows the location, you should be getting 56000/ 57000 rpms, good luck