Rough idle and high RPM's at startup on Pro XS

[MikeBelter]

I have a 225 Pro XS (2B122654) that started idling very roughly after a 15 min run yesterday. It was also hard to shift back into neutral. When I start the engine it revs up to 1500+ rpms immediately and then settles down to about 780-810...which is above normal. I had to get back in for weigh-in but I took it easy and it seemed to run fine when I got on plane with no missing. Today I tested it out a bit at idle and it seems to be surging about 50-100 rpms when idling in neutral and when I drive at idle speed the rpms seem to fluctuate about 20-60 +/-. Engine still revs to 1500 rpm+ when I start it. Any ideas?

[lpugh]

Check for fuel leaks under the cowl. pay particular attention to the water in fuel sensor in the front of the VST
If no fuel leaks are found you will need to leak down pressure test the fuel & air pressures @ 5, 10, & 15 seconds. You will need dual glycern filled gauge set (they are not cheap)

[JOE54]

^^^^^ +1 likely find a bad tracker valve

[MikeBelter]

There's some fuel seeping from the tube that connects the drain on the VST. But the problem I noticed was entirely happening at idle. When I ran on plane it seemed to run just fine.

[SilverFox579]

There's some fuel seeping from the tube that connects the drain on the VST.

There should NOT be fuel there.

[JOE54]

There's some fuel seeping from the tube that connects the drain on the VST. But the problem I noticed was entirely happening at idle. When I ran on plane it seemed to run just fine.

possible drain screws leaking on vst if that raw fuel is present inside cowl could be problem , leak needs to be repaired

[MikeBelter]

Yea I'm wondering why there was any leakage at all. The allen screws were not real snug though so that may be why. Not sure if that's related to my idle issue though. But at least something to report to the shop.

[JOE54]

easy to tell pull cowl off and start it allowing fuel vapors to be airborne

[EuropeanAM]

Might consider removing cowling and then pumping primer bulb firm. Visual inspection for leaks.

Cycle key ON. Again, visual inspection for leaks. If zero/no leaks seen, AND NO FUEL SMELL, start and visually monitor for leaks.

ANY FUEL LEAKAGE carries with it a risk of Fire or Explosion. This is something that must be corrected before running the engine on the water.

[21xTriton05]

There's some fuel seeping from the tube that connects the drain on the VST. But the problem I noticed was entirely happening at idle. When I ran on plane it seemed to run just fine.

Likely one of the drain screws is loose or the o ring is ripped on this. The black hose does nothing other than help you drain the VST into a bottle or something without it dumping in the cowl.The revving up is likely an issue with a rail diaphragm

[MikeBelter]

Yes it was a rail diaphragm. Two of them actually. The drain screws on the VST were just a little loose causing seepage.