my truck will start but sputters and back fires my uncle says the plugs are wet and making a yellow spark.

 

Clean or replace plugs and do a tune up with new points and condensor, cap and rotor if you are uncertain about their ageor condition. Lok under the hood with motor idling at night, garage lights off, to see if sparks are jumping around between wires. If the weak yellow spark persists have the coil checked or replace it. If all that fails check distributor ground wire which is inside under cap and see if it is in good shape, and not corroded or compromised. Also check the motor to frame ground strap and battery ground, cleaning each end for good contact.