I found multiple problems with this unit due to the harness. These harnesses are made with small wires and tight bends. I changed the one under the dash and the engine harness. If you are smelling propane then I would suspect the vaporizer. The pressures are supposed to be 4.5 to 5.0 PSI the plug on top is your test port these are not rebuildable. If you do change the harnesses you have a small on going to your cam and crank sensors as well. Also look a the load injector it's the small one next to the main injector. They have a plunger on them that stick from the gunk. Hope this helps.

I'm wondering if you even found out what the issue was? I have exactly the same problem, tcm 15 with a k21 starts and runs fine for a couple seconds then shuts off. Occasionally blows the injector fuse. Only code is for fuel injector. It also reeks of propane after like it is running very rich. Tried swapping the injector and nothing. A different tech changed the fuel injector ecu and that fixed it but two weeks later it started doing exactly the same thing. Not sure where else to look