well im stumped i have a 1992 3.0l mercruiser. it ran like a champ before i did a tune up, now it wont start. so i put everything back the way i had it when it started and now it wont start. im so confused i checked all the plugs plenty of spark and brand new battery. the motor will turn over just about to start and then just continue to crank. please help thank you:mad-new: