I have an older model riding mower w/an 18 horse briggs twin II and I
Rebuilt the carb and it ran fine for a little while but now it seems like
It is starving for gas! It has spark! Can anyone help me
Thanks Bill:

Try it without the gas cap, runs fine? Then move onto making sure gas is getting to it well from the gasline, take it off at the carb, let it go in a gascan, and watch for good flow. That's OK? Does it have a fuel filter? Still could be a clog in the carb, How did you rebuild it the first time? Usually its best to get a rebuild kit for it, tear it down, soak it in a bath type carb cleaner, blow it out with carb cleaner for extra, and compressed air through any and all holes you see.

Try it without the gas cap, runs fine? then move onto making sure gas is getting to it well from the gasline, take it off at the carb, let it go in a gascan, and watch for good flow. Thats OK? Does it have a fuel filter? Still could be a clog in the carb, How did you rebuild it the first time? Usually its best to get a rebuild kit for it, tear it down, soak it in a bath type carb cleaner, blow it out with carb cleaner for extra, and compressed air through any and all holes you see.
Thanks briggsdude
It was my gas cap it had no vent hole!! Thanks again! Bill

Glad to help. See if you can find a cap that will fit and vents and you should be set. You might can leave it loose for now.