Originally Posted by Strokin304
After having some electrical issues we replaced the main engine harness. Replaced starter and got new batteries as well. Truck turns over but wont fire up. Have fuel in upper bowl, have good high pressure oil (1.5-2 volts tested with meter while cranking.) Swapped FICM(mine tested fine but just to rule it out) with a known working one. There is small puffs of white smoke coming from the tail pipe while cranking. Any help would be greatly appreciated.
When you say puffs of smoke, is that supposed to mean it TRIES to start? If you so, I'm going to go out on a limb and say your issue is either insufficient fuel pressure and/or non-firing injector(s) causing your no-start issue. Just by virtue of the fact is TRIES to start tells me you have ICP pressure (1.5 to 2.0 volts is more than sufficient) and FICM_SYNC as well as SYNC. Does fuel fill up the secondary fuel filter housing instantly and overflow rapidly when you cycle the key to RUN? If so, you likely have more than sufficient fuel pressure. Do you hear ALL injectors pre-cycling when you cycle the key to RUN? If so, you need to get your hands on a scan tool that can run an Injector Buzz test. Listen carefully for buzzing of all eight injectors when the test commences, to be followed by clicks from each individual injector in cylinder NUMERICAL order (not engine firing order). The NON-CLICKING injector(s) will be the one(s) not firing that's likely causing your no-start, provided there is sufficient fuel pressure (about 56 psi or more at key-on/engine-off).