Problem with 2004 200 HPDI - WOT won't exceed 4800

[nemako]

Trying to chase down an issue...... Here is what has been done for Spring maintenance:

- Replaced main fuel filter, VST filter, canister filter after VST tank.
- New plugs, 10 micron Yamaha fuel/water separator element.
- New LP pumps, cleaned O2 sensor
- Compression #'s within spec/even across cylinders (slightly lower in bottom 2 which I have read is normal).

Had tech check HP pump (680 psi) and pump in VST tank (50 psi). Pressures remain steady at speed all the way up to WOT. Engine idles low when started (500 rpm) and runs rough idling through the harbor..... seems sluggish overall. Idle rises to 1300 after cruising for a while. Not sure what to check next...... any help would be appreciated. Thanks.

 

[jeffersondodson561]

Re: Problem with 2004 200 HPDI - WOT won't exceed 4800

How about TPS voltage? Sounds like everything fuel wise is in spec to the engine. I would have mechanic syncronize the throttle plates and maybe a fuel vacuum test of the fuel system. Fuel restriction? How about crank postion sensor output?

 

[nemako]

Re: Problem with 2004 200 HPDI - WOT won't exceed 4800

I asked the tech about TPS voltage and he said it was within spec. He also did a feul restriction test which simulated peak flow and it did come back a little high. After replacing the primer bulb with a new Yamaha unit, it came down but still at the top of the acceptable range. I am going to check my tank pick-up and the anti-siphon valve next. My tank is only 3 years old, so no debris unless it entered the tank at a fill-up. Tech is looking at the boat again this week and plans to check the O2 sensor. The low idle at start-up is strange, almost like the cold start sequence isn't working. Maybe the O2 sensor is bad?

 

[jeffersondodson561]

Re: Problem with 2004 200 HPDI - WOT won't exceed 4800

O2 sensor will not have anything to do with low rpm ranges just higher "closed loop" rpm ranges. You have to remember all of the computing done by the computer is done with the assumption that all mechanical devices i.e. fuel vacuum, fuel pressure, regulator function are working properly.

 

[nemako]

Re: Problem with 2004 200 HPDI - WOT won't exceed 4800

Update..... Tech came back out and the engine threw an injector code when put in gear. #5 injector was not getting signal from driver (verified by swapping outputs). Spark plug in that cylinder looked brand new. I pulled my injectors for testing/cleaning and purchased a replacement injector driver (I have the dual setup). Should get things buttoned up this weekend. The injectors were a PITA to get out.... should I grease them when reinstalling? I have some synthetic grease or could buy something else.

 

[stylesabu]

Re: Problem with 2004 200 HPDI - WOT won't exceed 4800

silglide is great for injector o-rings. also always a good idea to keep a good clean 6 gallon tank of gas to double check fuel. most of my small engine troubles are fuel related( my fault for not keeping them dry. only mention because boats don't get used everyday and spend a lot of time outside