First off, with fuel mileage that bad, I would be looking for a gas leak somewhere. If the sled was pumping gas through the engine at that rate, I would think it would be running poorly, like showtime4 said. If no leaks are found, then look for parasitic friction losses all through the sled. Here are some ideas for you.
Check the ski and track alignment. Center the track and make sure it's not too tight. Adjust the skis so they are toed out no more than 1/4". How are the hyfax and track clips? Worn hyfax or missing track clips can really make some friction.
Check the carbides. Are they straight? A bent carbide can really cause friction.
Check your clutches for proper offset and deflection. Any twisting motion in the belt will really rob power. How is the belt? A worn, slick belt will not transfer power well. Clean any belt residue off the clutch sheaves so the clutches can grab the belt efficiently. Use a degreaser and hot water, then scrub the sheave surfaces with a Scotch-brite pad or 200 grit sandpaper. The sheaves work better roughed up a bit than if they are slick.
Check the bogey wheels for a bearing that is frozen. Check the brake to make sure it's not hanging up (not likely, but it happens!)
Pull and clean the carbs. Check float height, and for proper jetting. What color are the plugs? You may be able to jet a size or two smaller to get better fuel mileage. You may have a jet that has fallen out or other problem in a carb. It's worth checking.
I would do all this before worrying about timing issues. It's not often that a stator plate gets loose. It could happen, but that would be really down on the list.
Good luck! I had a 440 Indy that was getting 6 mpg, and did all the above and got it up to 12. It ran great too, but the problem there was clutch offset and rich jetting. It took a while, but you should be getting better than 3-4!
