My otherwise always reliable 2003 Volvo 5.0 GL-B engine stopped a few days ago while my son was towing some friends on tubes. It stopped at speed, with no warning. Wouldn't start. While getting towed to the dock (only a couple of hundred yards away), it started again, but only at idle, and then quit after about 10 seconds. I changed the fuel/water separator, but no affect. Then I looked down the carburetor (not fuel injected), and saw no evidence of fuel when either advancing the throttle at idle, or when turning the engine over. So...what else should I check, and/or how do I confirm that it is the $235 fuel pump before I spend the $$? What else should I check first? Thanks!