My 2000 f350 7.3 with 81250 miles has become a bear to start after it has sat for 12hrs with temps in the mid to high 30's( Burlington County,NJ near FT.Dix) I plug it in at night but have no access to a plug at work where it sits for 12-13hrs during the day. I think my glow plugs are the problem. Anybody else think of anything else that could cause this? Thanks

 

Glow plug relay is a common problem. The glow plug relay is the one closest to the front of the motor in back side of fuel filter.

 

If you think it might be the glow plugs a quick test to do on them , Dont forget to check your fuse's !!!!

Take a common ole circuit tester , the kind with a clip on one end an a poker on the other ( test lite ) , hook the clamp end to the battery postive , an pull the wire off the glowplug, touch the end of the test lite to the top of the glow plug , if it lites up it shows the glow plug is good. ,,,

If it dont lite up the glow plug has shorted out an needs to be replaced. the lamp acts as a resiter. dont ever hook a straight hot wire up to the glow plug it will fail very quickly !!!!!

Theres no sense in replacing all the glow plugs at once , there expensive to boot, Ive seen guys replace them like spark plugs , its a waste of time an money

 

and if all your glow plugs are good check the module next

 

I'm no expert on diesels but I've done a few computer based classes just to satisfy the boss. I have no interest in being a diesel tech so I've really just done what I had to do to pass the classes. As hard as I tried not to, I still learned a few things. I learned that the injectors are in some way driven through the oil system. You have the regular pressure oil system for lubricating moving parts, then you have the high pressure oil system to drive the fuel injectors. At the top/center/front of your engine should be a bolt w/ 1/4 inch drive square socket which when removed will let you check HP system oil reserve. It's possible that the system is allowing the reserve oil to flow back down into the oil pan and taking time for it to build pressure again to get the injectors working. Another important factor is the proper oil grade and viscosity. 15w/40 is specified for newer 6.0 and 7.3's in normal temperature. 10w/30 is recomended for colder area's. Make sure oil level in pan is correct (fresh oil/filter change takes 15 qts)

When it's cold, open up that inspection hole and take a peek inside. If it's not within a half inch of the top, fill it with whatever grade oil you used during your last oil change then try starting it up. I bet it will start pretty easily.

You haven't fixed the problem at this point, but at least you know where to start looking. High pressure oil system for injectors.

 

I had the same problem and it wound up being a relay module for the glow plugs. I think it was about $200 for the repair at the dealer.

 

you are right around the millege where glow plug failure is common.