2004 Mercury Optimax 225 Stalling

rapishorrid

Seaman Apprentice
Joined
Apr 2, 2016
Messages
30
The other day my '04 Optimax 225 began running poorly while on the water. It was revving in neutral, wouldn't shift easily and was struggling at higher RPM's in gear. In neutral the alarm would go off continuously, but then disappear when shifted into gear - so we slowly limped the short trip home in gear. At the dock we discovered that the entire lower cowling had filled with fuel. Turns out the water-in-fuel sensor (#30 on the VST diagram below) had disintegrated allowing fuel to flow freely out of the VST. ?

With a new sensor the motor starts, idles and runs great all the way up to WOT with no alarms. The only problem is that it's still difficult to shift into reverse, and the motor sometimes stalls completely when shifting or when initially throttling up from in-gear idle (this can be avoided by continuing to throttle once it stutters). This never happened before the water sensor failure. ?

Since we did have to remove the entire VST to access the sensor, which includes disconnecting the high pressure lines to the fuel rails - my first thought is that there's a fuel pressure leak on one of these connections (although there is no visible leak). But then again I would think a motor with a fuel delivery problem would not perform flawlessly at WOT...?

Thoughts??

VST Diagram
 
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