I have an old Briggs and Stratton 3.5 classic engine. When the engine is dead cold, the primer has trouble sucking in fuel. The primer itself is in good condition. After about 10 pumps on the primer, I can finally feel fuel coming in and my mower is ready to start. When the engine starts, it hesitates on idle and I have to push the primer to force fuel into the engine or else it'll stall. After doing this for about 3 minutes, the last 2 minutes where it is forcing fuel itself, the engine is weak. After about 5 minutes, or when the engine is warmed up, it goes to full power and back to normal; starting is good and strong with one pull.
Note: All maintenance has been done and I put carb cleaner mixed with gas every year.
Note: All maintenance has been done and I put carb cleaner mixed with gas every year.