04' 250 HPDI not screaming and flying

[LOWTYD]

Hello all, I believe this may be my first post on here since I joined a while back. I've always used the forums for research and guidance but now I have an issue that has been addressed several times here and in other boards. The dreaded "HPDI sluggish, missing and will not rev above 4k RPM's." Anyway, I figured it was the VST so I pulled it and it was spotless, canister...everything, not a speck of anything in it. I pulled the VST screen anyway and hit it with some carb cleaner and blow it out with an air nozzle. It looked the same after as when I started, clean. Put everything back together and pulled my plugs, they were carboned up pretty good, not caked but definitely small chunks so I cleaned them and put them back in. No water in the motor mounted water separator. Filter there looked clean as well although I know I should replace it also. While trying to eliminate variables today, I was choking to make sure I was holding pressure on the bulb once it was tight and noticed when I looked at the VST, I noticed a small amount of gas seeping from the case where the two halves come together. It does not leak there when running, only once you shut the motor down. I see where this could cause fuel starvation, but not the missing. Planning to get new VST screen, gasket and mid fuel filter. Any help diagnosing this issue would be greatly appreciated.

[R.grover]

Replace that gasket.
Do a pressure and vac test on the fuel system.

[LOWTYD]

Replace that gasket.
Do a pressure and vac test on the fuel system.

Picking up parts today. Can I check pressure at the Shrader valve in top of the VST tank? Is that tank pressure, fuel pressure or something else.

[DoktorC]

I'd replace the Yellow pickup filter in the VST and the chrome canister filter on the output line of the VST to start....and change the VST o-ring (they are a PAIN to get back into place if they come out when you split the canister..)

[LOWTYD]

Thanks. Yesterday, I put the o-ring in the freezer for 20 minutes or so, hoping it would shrink down and stay on in place while I put the halves back together. I didn't use anything like grease or Vaseline to hold it in place either. I'll make sure I do it on the fresh gasket so it doesn't get pinched or moved out of the indention.