Turpentine
Turpentine is one chemical that removes pine sap from your wooden deck. Apply the chemical directly to the sap or with a coarse sponge, then dab the sap thoroughly. Use a dull putty knife to scrape away any sap residue. Follow up the removal by scrubbing the area with a stiff-bristle brush in the direction of the wood's grain. Do not over-saturate the wood with turpentine.
Turpentine is available at hardware, home improvement, chemical supply, paint supply and retail superstores. The chemical is safe to use on wood and around grass and landscaping. Wear rubber gloves and a nose mask to keep the chemical off your hands and out of your nose.
Sandpaper
Sandpaper is a non-chemical method of removing pine sap from your wooden deck, but it is a slow removal method. Use medium-grit sandpaper to sand the sap in the direction of the wood's grain. Use a new piece of sandpaper when the old one becomes gummed up with sap.
Deck Stripper
Another way to remove pine sap from your decking is by using a commercial deck stripper. Spray the chemical on the sap and use a long-handled brush to spread the chemical. Let the deck stripper stand for 10 to 15 minutes, then rinse it off with a water hose. Deck stripper is safe for use around grass and landscaping, but you need to wear rubber gloves and a nose mask to protect yourself from the chemical.
Note, deck stripper can leave a fuzzy residue on your deck's wood. Use a piece of medium or fine sandpaper to remove the residue, then apply a sealer to the decking.
Follow-Up
Rinse your wooden deck thoroughly with water to remove any sap and cleaner residue. If desired, mix 1/2 cup of dishwashing liquid and 1/2 gallon of warm water in a bucket and pour the solution onto your deck to remove any dust and dirt. Rinse the deck and let it air dry.