Pull the fuel line off from the carb & crank the engine
You should get a strong flow , perhaps pulsing a bit if all is good
If not then you have a fuel supply problem so you trace it back, one item at a time
There are 6 things that can cause poor fuel flow
1) floating debris being sucked into the pick up tube forming a plug ( by far the most common )
2) failure of the venting system, particularly those with charcoal canisters ( No 2 )
3) delamination of the fuel line collapsing and blocking off the flow
4) ON JD's with hang down pick up tubes, cracks in the tube ( works ok when the tank is totally full the stops when the level drops )
5) bad impulse connection to the pump ( impulse pumps only )
6) failure of the impulse pump.
Note the pump is the least likely to be your problem but usually the first thing people replace for no good reason .
