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Mat
Mat, Ford Senior Master Technician
Category: Ford
Satisfied Customers: 975
Experience:  11 yrs at FLM Dealer, Senior Master Tech 05-present, ASE Master tech, Auto trans & Diesel
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ford f350: starts hard..new glow plugs runs ruf until warmed u p

Resolved Question:

ford f350 2005 6.0 starts hard wen cold has all new glow plugs runs ruf until warmed u p
Submitted: 5 years ago.
Category: Ford
Expert:  Mat replied 5 years ago.
Hi I would like to help you out. Hard start 6.0L is a symptom of a weak ficm. Fuel Injection Control Module. These injectors run off 48 volts, not 12. The ficm has a dc to dc converter internal to it that takes the 12v input and converts it to a 48 volts for the injectors. When cold the glow plugs run and draw allot of power from the batteries, this lowers voltage input to the ficm causing the dc to dc converters to work harder. When these dc to dc converters get stressed out cold they fail to make 48 volts, When the power drops below 40 volts it makes the truck very difficult to start. When the truck is hot it will restart normal because the glow plugs dont run when oil temp is over 110 degrees and the batteries are just off recent charging from the alternators so they are strongest then. The truck runs rough when cold because the power to the injectors is allot less than required and they cant function as designed. Codes are usually set. a p0611 and sometime all 8 injector codes, these codes do not set the check engine light so you will have no visual warning.The ficm will need to be replaced. Now you have two options a full ficm is around $750 and needs to be programmed by the ford dealer upon installation or else the truck wont start, A ficm half shell is about $550 and requires no programming. The half shell comes with instructions and is easy to replace. The ficm half shell contains the half of the ficm that houses the dc to dc converters that have failed. please reply if you need a follow up. Thanks
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