Specs:
Year: 2014
Make: CombiLift
Model: C6000CB
Engine:3.0 GM IMPCO Tier 4
Good Afternoon, I have this unit (listed above) and I'm not seeming to get spark and I believe fuel injection aswell, Unit was running great and driving under its own power for days. I let the unit sit over the weekend I come back to a crank no start, I've replaced a lot on this unit as it is a Recondition Job, and I received this truck in literal pieces on 3 pallets. I've replaced the starter, plugs, wires, dist. Cap and rotor, completed a head job, all fuses and relays, battery, throttle body, radiator, so on so on, this was before it wouldn't start and it ran great, no CEL, no codes, no missfire, no rough idle, unit was done and got painted, receive the truck starts runs fine, let sit over the weekend and come back to the no start, diaging the problem I found no spark, checked continuity on wires going to distributor and they are good, going to coil, they are good, confused I replaced all the engine fuses (only 3 of them) and it started but ran rough and had codes, codes came up to be injectors 1-4, deleted the codes and the CEL stayed off, turned unit off and wouldn't start back, replaced the fuses again and still won't start, I leave the truck alone to work on another job and come back to it, unit started and running rough, this time no codes, confused I used the IMPCO systems and disabled injectors one by one to find the missfire, cyl 4 made no difference when deactivated, checked injector wires and got intermittent power, checked continuity and it was flawless (checked harness and no nicks, bends, cracks, etc) checked the rest of the injectors, same thing but only injector 4 wouldn't make a difference in the way it ran, replaced all 4 injectors, and went to turn it on, no start, irritated I check all wires to ignition (spark and fuel) and getting 0v on everything key on, spoke to combilift themselves and was givin the run down on what to look for, how to diag and found a relay that gave power to all ignition related systems (spark and fuel), relay tested good, used my meter to check voltage and noticed when key on I would get power for about 1-2 seconds and then nothing (usual with fuel injected systems to deliver fuel to the combustion chamber) but when the key was turned to the start position I would still receive 0v on all systems (unit will still turn over) key back into on and still no power, turn the truck off and turn it back to on and still 0v, but if I kill the truck with the red kill switch and turn it back on I get 12v for the same 2 seconds and then back to 0v, even stranger I will get SPARK just by turning the truck in the on position for the 1-2 seconds it gives power, I'm lost on what this could be, combi rep said Computer is bad or a bad crank sensor, replaced crank sensor to no avail, anyone else seen this? Any other routes or measures I should take? I apologize for the long read, but a lot was done and I'm still not receiving power as I should, thanks for the help.