On my Yamaha S250TXRV (ox 66 efi v-76 1997) - <br />My engine is back to it's old tricks - rpm drop off at speed and occasional trouble idling. I called the shop which repaired it last time and spoke to the mechanic. He did not hesitate to tell me that the culprit was probably the screen in the vst tank.(there was lots of debris in the fuel last time and he cleaned the screen and replaced the fuel pressure regulator - at which point the engine ran perfectly) I removed the tank and cleaned the screen and reassembled the unit. It seemed to run really well for about five minutes and then back to it's old tricks.<br />When I returned to the house I pulled the vst tank again and found it was leaking at the back of the unit. Upon closer inspection, I found a broken o-ring causing the leak. Could this now be the problem with fuel pressure? (I ordered a new o-ring and am hoping this solves it)