I have a 2001 Yamaha VMAX 150 (carb) that has been intermittently dropping about 1000 rpm. Typically, it will drop to 4000 rpm from 5300 rpm while I'm running it. Sometimes this go on for hours, sometimes minutes. Sometimes it will run fine the next time I crank it, other times it won't. I brought it to the dealership twice already. Both times they told me they thought I had water in the fuel. After the first time, I drained the tank. After the second time, I had them install a Racor water seperator in the fuel line. In both instances they said they flushed the carbs and it ran fine. Both times it ran poorly when I put in the water. When this problem presents itself, it runs fine in neutral; but under a load the power loss is very evident. When this occurs, Ive noticed that when I reduce the throttle it surges when I get to about 1/3 throttle. Any suggestions? I'm growing weary of hearing "water in the fuel" from the guys at the dealership when I see no evidence to support that.
