John Deere 115 lawn tractor - won't start. Replaced fuel filter, fuel pump, spark plug, oil filter (changed oil), but still won't start. Engine cranks, but won't run.

Here's the link and I'm sure you will get the solution of your problem.
John Deere D110 Lawn Mower Tractor Workshop Service Repair Manual

Specifications

Engine HD45

Engine Model Number(Kawasaki FC420V
Horsepower (10.5 kW (14 hp)
Displacement (423 cc (25.8 cu.in.)
Crankcase Capacity w/o oil filter (1.3 L (1.4 qt.)
Crankcase Capacity with oil filter (1.6 L (1.7 qt.)
Spark Plug-Gap (0.64 mm (0.025 in.)
Spark Plug-Torque (20 N·m (15 lb-ft.)
Cylinders (One
Stroke/Cycle (Four
Lubrication (Full-Pressure
Oil Filter (Standard Single Element
Air Cleaner (Dual Stage

Engine HD75

Engine Model Numbe(Kawasaki FC540V
Horsepower (12.7 kW (17 hp)
Displacement (535 cc (32.6 cu.in.)
Crankcase Capacity w/o oil filter (1.6 L (1.7 qt.)
Crankcase Capacity with oil filter (1.9 L (2.0 qt.)
Spark Plug-Gap (0.64 mm (0.025 in.)
Spark Plug-Torque (20 N·m (15 lb-ft.)
Cylinders (One
Stroke/Cycle (Four
Lubrication (Full-Pressure
Oil Filter (Standard Single Element
Air Cleaner (Dual Stage

Fuel System

Fuel (See Fuel in the Service Miscellaneous section
Fuel Filter (Single Stage, 60 Micron
Fuel Pump (Vacuum Operated-Diaphragm
Fuel Delivery (Gravity Feed to Fuel Pump)
Fuel Tank Capacity (19 L (5.0 gal.)

Drive Train Mower Deck (36-inch)

Blades (2
Blade Bolt Torque (81 N·m (60 lb-ft.)
Cutting Heights (25-114 mm (1-41/2 in.)
Weight (86.7 Kg (191 lb)
Overall Width (chute up) (927 mm (36.5 in.)

Mower Deck (48-inch)

Blades (3
Blade Bolt Torque (68 N·m (50 lb-ft.)
Cutting Heights (25-127 mm (1-5 in.)
Weight (83.6 Kg (184 lb)
Overall Width (chute up) (1308 mm (51.5 in

ower Deck (54-inch)

Blades (3
Blade Bolt Torque (68 N·m (50 lb-ft.)
Cutting Heights (25-127mm (1-5 in.)
Weight (86.7 Kg (187 lb)
Overall Width (chute up) (1460 mm (57.5 in.)

Recommended Lubricants

Engine Oil (John Deere PLUS-4
Grease (John Deere MOLY HIGH Temperature EP
Transmission Oil (HY-GARD-J20C (TURF-GARD-SAE10W-30 (PLUS-4-SAE10W-30 (TORQ-GARD SUPREME-SAE30
(Specifications and design subject to change without notice.)

Check your fuel filter and change it if you havent changed it in a while

Sounds like a faulty fuel pump.Did you check that?

in the carb did any of the screws have any micro bored holes for gas to go through like in many small engine iv found . clogged with goop. does it have a gas bowl an a screw on bottom take it out if does an look it over close.

Change your fuel pump.

some models have a fuel pump some are grivitey

If the starter motor is actually turning the engine then the first thing to do is check the spark plug to see if you are actually getting a spark. If there is a spark, then move on to the fuel system to eliminate restrictions in the flow. The problem could be due to a dirty fuel filter, faulty fuel pump or solenoid fuel valve, no voltage on valve or dirt in the float bowl or a blocked float valve.
Have a look at these tips for troubleshooting lawnmower starting problems. They apply to tractors also:

http://www.fixya.com/support/r9118692-lawnmower_not_starting

Unless you have a diesel, the black smoke at start up is not normal, it should be white if anything. It sounds like you are burning very rich, or no air at all, check the air filter, check the fuel cond, check the governor thing, make sure it moves freely and rebounds. Change the spark plug. I don't know what else it could be without being there. The carb could be clogged up, some carb cleaner wouldn't hurt. Hope this helps.

How old is your ? Sounds like ignition problem,If your engine is older you would have points when the points are bad they can stick together and will result in shutdown after unit cools a little it will restart !