1200 Non PV Running Issue

[ktyamaha36]

I have a Yami SUV with the 1200. Has had oil B/o kit installed for 5+ Yrs now mixing at 40:1.

It ran great and have never had a issue with it. Last time it was out it started cutting out and would not stay running unless you pulled the choke at idle, and would barely get up on plain . (Lacking Fuel). Let it sit all summer. Just got done pulling the carbs, Cleaned them up (Minimal trash in filters) Blew all the ventri's and jets out and put them back together. All diaphrams and gaskets were in great shape! Changed the fuel lines & filter also. Put fresh gas in it and took it to the lake.

Now it Idles great, give it WOT and it gets up and goes, Will run around the lake all day at WOT. It seems to still have a fuel issue at 1/2-3/4 throttle. From Idle it will get up on plain and run for a few seconds then act like its running out of fuel. Let off and pump the throttle a few times then go to WOT and it hauls a$$ all day again. So from an idle to WOT there are no issues, but try to cruise 30+ MPH its a no deal...

Do you guys have some ideas on what could be causing it to loose fuel at mid throttle? But be fine at WOT? Plugs look good. Its def a fuel delivery issue, just cant pin point it!

Any help with this thing will be great its driving me nuts

[Dapal79]

my suv was having some fuel issues as well...not the same that you describe but i found that my check valve that vents air into the tank was not working properly. I'd say it's worth the 5 min it takes to remove it and test it.

[jim mcgreehan]

...also, do those carbs have an accelerater pump on them that you could check(?).