'96 Yamaha 225 2 stroke. Model L225TXRU
Problem: Engine stalls if idled for very long. Fuel pumps won't deliver adequate fuel at idle. Good fuel flow at higher rpms. Engine runs rough and has knocking noise when trolling at idle speeds. Runs great at all other speeds.
I've changed out all 3 fuel pumps. I have replaced primer bulb, and fuel line from tank to bulb. I have bypassed fuel line altogether and run from separate portable tank.
I used clear tubing at the output of each fuel pump. Noticed lots of bubbles on the top two pumps but the bottom one looked pretty good. Switched top and bottom pumps and the bubbles still existed on top pump so it doesn't look like it's a pump problem. Also, all 3 pumps work well at any speed higher than idle.
Is there a way to test vacuum level? I wonder if there just isn't enough vacuum (or a leak somewhere) to adequately drive the pumps. If there is a way to test vacuum, what should the vacuum level be at idle?
Any other ideas of what could cause this problem?
Problem: Engine stalls if idled for very long. Fuel pumps won't deliver adequate fuel at idle. Good fuel flow at higher rpms. Engine runs rough and has knocking noise when trolling at idle speeds. Runs great at all other speeds.
I've changed out all 3 fuel pumps. I have replaced primer bulb, and fuel line from tank to bulb. I have bypassed fuel line altogether and run from separate portable tank.
I used clear tubing at the output of each fuel pump. Noticed lots of bubbles on the top two pumps but the bottom one looked pretty good. Switched top and bottom pumps and the bubbles still existed on top pump so it doesn't look like it's a pump problem. Also, all 3 pumps work well at any speed higher than idle.
Is there a way to test vacuum level? I wonder if there just isn't enough vacuum (or a leak somewhere) to adequately drive the pumps. If there is a way to test vacuum, what should the vacuum level be at idle?
Any other ideas of what could cause this problem?