Duramax Lifetime Supporter
Join Date: Aug 2012
Location: Carson City, NV Proud Participant, Federal Witness Protection Program
Glow plugs are digital in that they work or they donít and from your original post, you have replaced everything related to their operation, including the plugs.
Also, as I mentioned in my earlier post, above a certain temperature (maybe 50?) I donít believe they are essential for startup since the heat of compression is enough to ignite the fuel.
Most owners with starting issues have a problem opposite to yours which is related to the return circuit inside the injectors. When cold, the thicker diesel fuel is not particularly bothered by a sketchy return ball/seat, but on a hot start the thinner fuel bleeds past the defective ball/seat, causing rail pressure to be below the minimum required to ďwake upĒ the Fuel Injection Control Module.
Long crank times or no start is the result.
Since you seem sure your glow plugs are lighting up, I think the next thing to do is determine rail pressure during a cold crank. Why your system would do the opposite of most no-start, injector related situations is a mystery, but knowing rail pressure needs to be checked before proceeding with other tests.
There are apps available for use with an OBD2 transmitter ($25) and work on a smart phone (Android or iOS) that will tell you rail pressure and much more.
Or go to a reputable shop and have them run diagnostics. By the way, are you getting an MIL lamp? Codes?
That big chunk of change you dropped at the last place has got to hurt and I think many of us have been there.
2003 GMC Sierra 2500HD SLE ExtCab CA Emissions; 155k; Allison 1000 w/Transynd X2 Flush & Fill; 8' bed; AFE/CAI; MBRP 4" Exhaust; Side Tint, 33% VLT, rear, Limo; Smittybilt Stainless Side Nerf Bars; Sprayed-in Bed Liner; MadJack Fuel Filter Access Door; Regular Used Oil Analysis (latest available on request), Blackstone Labs; EGT/Boost Gauges; Dual Chrome Dipsticks, JC Whitney; Stainless Steel fuel filter head bleeder screw; New WP and Hydroboost; Billet Aluminum Fuel Filter Housing Spacer; Professionally repaired instrument cluster (new steppers and lamps); Does anybody ever read this s%#t?; Injectors under warranty @ 70k; 2nd set DIY @ 155k