Small Engine Troubleshooting Problems? Ask a Mechanic Now.
Make and model ? Same problem with old carb?
Briggs single cylinder OHV engine. Was old carb doing the same? Is the exhaust open and not plugged with debris?
Remove exhaust and test run without it!
If old carburetor did the same , exhaust may be plugged. But if it is just with new carburetor, the float and needle valve can be stuck!