Yamaha f40 suspect fuel starvation.

[cheetahcat]

Hi guys have a pair of yamaha f40 fuel injected models 2012 model years. I am having issues with the one, basically intermittently it will start surging and not rev over 2000rpm, sometimes eventually it will clear and run spot on up too full revs but if you go back to idle the fault re- occurs.seems like fuel is not being supplied, have tried different fuel line and bulb , tank, replaced fuel/water seperate filter and spark plugs, there are no fuel or visible air leaks. I suspect the low pressure fuel pump is playing up, any suggestions other than maybe swapping the pumps from one engine to the other, thanks in advance.

[99yam40]

test fuel pressure while problem shows up

I do not know how you looked for air leaks before, but slip a clear piece of tubing in the system after pump to watch for air bubbles during testing.

[MSmith1227]

Check to see that you are getting water flow through your fuel cooler.