Yamaha TRX850 Enthusiasts Forum

Had my fuel pump slowly die over a period of a 1000km or so. At first drop off of power was hardly noticeable but slowly got worse especially on long straight runs with no throttle movement. While trying to find problem checked pump which seemed to be operating ok so went on to other possible causes only to eventually come back to the pump. Replaced it, end of problem. Got me thinking tho' about the vacuum side of the fuel system. I can understand the pump running on vacuum but don't know what the vacuum tube to the fuel tank does. Any ideas?

There is a rubber diaphragm inside the fuel tap that stops the flow if there is no vacuum.

Cheers for that.