6.0 diesel has been hard to start. turn switch off and on 4 times to eventually start. now with 2 new batteries it wont start and only turns about 2 revs. egr delete just installed with complete kit. had fuel leak on side of fuel filter housing. replaced o ring.. not cam sensor because tach works while trying to crank. this is my sons truck to work and back dont know what to check next. can you please help. thanks.