Car is a 1992 Buick Century sedan with 3300 V6 engine and automatic transmission. Engine has about 80,000 miles which is low for its age. Car was running several months ago but just quit while driving on the highway. My friend has replaced lots of parts with the "shotgun approach" in hopes of getting it to run. ECM (engine control module), ICM (ignition control module), crank position sensor have been replaced with used parts. Starter will spin the engine but no attempt to start. I do not know if the used replacement parts are good. Today I attempted to assist with a methodical approach. This engine has individual port fuel injection with a distributorless ignition. All 6 electrical connectors at the injectors were removed. I checked the resistance of the injectors and 5 had values of 12.5 - 12.8 ohms. Number 6 injector had a resistance of 10.5 ohms. Online research tells me that the proper resistance should be in the 12 - 15 ohm range. I don't know if that low injector resistance on #6 could be a problem? With all 6 fuel injectors electrically disconnected, I removed the air filter housing and sprayed starting fluid directly into the throttle body while the starter was engaged. Engine did not start. I removed the spark plugs on cylinders 1, 3, 5 which are closest to the radiator. I reattached the plugs to their respective wires and laid the plug body on a metal engine support and engaged the starter. All 3 plugs had spark jumping the plug gaps. Since this engine fires the plugs in pairs, 1 & 4, 2 & 5, 3 & 6, my spark plug test confirms that all 3 coils are good and all 6 plugs are receiving spark. I checked the routing of the spark plug wires against a known, running 3300 V6 engine and the plug wires are correct between coil and respective plugs. Since I am getting spark at the plugs, I am assuming that the crankshaft position sensor and ignition control module are functioning properly. Since I disabled the fuel delivery and used ample starting fluid in the intake, I will assume that the no start is NOT due to fuel delivery issue. When spark plugs 1, 3 and 5 were removed, I placed my thumb over the opening and had the engine cranked with the starter. There was noticeable compression but this is a crude way to check compression. I am wondering if the crankshaft pulley has somehow slipped on the crankshaft and is out of time? Since it is keyed to the crankshaft I would think that unlikely. What have I overlooked? I am open to suggestions.