Yamaha 70 TLRY not keeping prime at full throttle

[gatorsc]

I have a 2000 model yamaha 70 TLRY. It will run fine up to 3/4 throttle. But once I open it up to full throttle, it looses prime. It will run at full throttle, but I have to assit it by pumping the in line priming bubble. The vent on the tank is open, and fuel connection look good. I replaced the priming bubble, but still having issues. I do have a water seperator on the system, and putting a new filter on it now. Just wondering if anyone had any suggestions on what else to try. Still wondering if maybe a loose fuel line connection some where could posibley allowing it to "catch air" and not run properly. Any input is appreciated!

[robert graham]

Maybe you just need to replace the fuel pump. Everything you've described points to a bad fuel pump. Good Luck!

[pman]

Gator- Did you try replacing the fuel pump as Robert suggested? I have the same 2000 70hp Yammy with the exact same problem you have mentioned. Never even thought about the fuel pump, but that certainly makes sense!

Pearsall

[99yam40]

It is best to test the fuel pressure and vacuum it can and does pull and see if it is sucking air into the fuel system. That will point to any problems

[Jockey]

How do we test that 99yam40 I have the same problem on a 2002 F60.

[99yam40]

search in the frequently asked part of the forum for testing fuel system

[stylesabu]

i chased it problem for 6 months didn't happen all the time.it turned out to be an o-ring in one of the quick disconnects. I happened to see it drip on day in the driveway. i had pumped up prime and just let it sit. it should take hours for it to get. ive seen other stay hard for a day.point is smallest leak can cause loss of prime.fuel pump kits are pretty cheap and like water pumps should be replace as prevent maint.