Duramax Lifetime Supporter
Join Date: Aug 2012
Location: Carson City, NV Proud Participant, Federal Witness Protection Program
Hello and welcome to the Forum!
As you have learned, relying on advice from the PO can be risky, unless the CP3 was professionally diagnosed, in writing.
“... cracked the line to the fuel rail tee and 1&8 inj and got fuel.”
A visual indication of fuel at the points you noted above says nothing about fuel pressure there but If it is adequate, whatever pressure sensor that is talking to the FICM may be defective or a signal is not getting to the FICM because of a wiring problem.
As you probably know, the Fuel Injection Control Module (FICM) will not wake up and fire injectors until it is informed of around 5000# of rail pressure. I’m not sure where the FICM gets that signal, but should be easy to learn.
Can’t recall where you can tap an injector firing signal. Relatively high “fire” volts that drops down to “hold” volts I believe.
Or, all is well up to the FICM and injectors are not firing because it is defective. Good move on pulling glow plugs to check there. If GP’s are still out, R&R of those inexpensive items would be a smart move.
Some things to consider and I’m sure others will weigh in.
Keep us posted.
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