I have a Miller Bobcat 225. It will not start and run with out pouring gas into the carb? I have changed fuel line and filter? Help!!! Please

Visit the on-line store, know as reliable-store, they have the repair manuals. I'm sure you will get the solution of your problem.
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did you try a touch of starter fluid in the carb just to verify that the engine is getting spark? ethanol gas... if it hasn't run in a few months and you left the gas in it... you better revisit the carb cleaning

Onan engine? If so, check your fuel pump. It will be located on the engine cowling. You'll see 2 fuel lines, one on top and one on bottom. These are the fuel in/out lines. The line you WON'T see is the vacuum pulse line that hooks to the rear of the pump assembly behind the cowling. This line operates the pump via a vacuum pulse created by the engine.
You can remove the pump mounting screws and the pump will pull away from the cowling a short distance exposing the vacuum pulse line. Make sure it's attached and not dry rotted. If the engine has set up for any extended period, there's a good chance the pump gaskets are "glued" to the pump chambers (internally) by bad gas and not allowing the vacuum to pump the fuel. Onan has (when I was working on them) kits for these fuel pumps and I've installed them successfully, but it might prove to be somewhat tedious if you're not well versed in kits of this sort or not extremely mechanically inclined. But if memory serves, a new pump was priced within reason. Good luck.

Will it start if you put a little gas in the carb before cranking? if it fires then, sounds like a stuck fuel shut off valve, located on bowl. one wire going to it.

ethanol gas.... probably turned your fuel line to jelly

Replace fuel pump.

I had a problem like this a few days ago try taken of the air filter to were u can see the choke it may not be opening rite just cause it opens don't mean itsnot opening rite get a small spray bottle put gas in it and as u start ur welder spray the choke with with the gas a lil if it starts turn ur switch to run for while it workd for me if that don't maybe change the spark plugs

The fuel pump is one of the probable faults, or the needle valve in carb is stuck in closed position.

If the fuel hose is removed at carb, it should squirt gas as the engine is cranked over. If not, look in tank to see if the screen on the barb threaded into the tank has not clogged up with debris. If it is clean, replace fuel pump.

If it squrits gas- open up the carb and check to make sure the float is able to pull the needle valve down as well as the float level setting. When the bowl is exposed, look for sediment as well.

Sounds like a fuel pump to me.

Check the oil safety switch maybe it is bad. It will stop running if low on Oil or wont start.