I have this generator that seems to run out of fuel every 15 minutes. I have a clear fuel filter inline with the hose that runs from the fuel tank to the carburetor. Its all gravity feed. Anyway when the generator sits the fuel filter fills up. Once the generator is started you can watch the fuel in the clear filter slowly go down over 15 minutes until the generator starts to surge and run out of gas. Once you turn the generator off the filter slowly fills back up with fuel. Does not seem to matter if the fuel cap is on or left off. I removed the fuel filter thinking it may be an issue causing a restriction but the generator still does the same thing. Its like the tank can supply the carburetor 90% of the fuel it needs and but cant keep up with demand. What should i check?