I just finished swapping out my flywheel, clutch assembly, and manual transmission. The car started and ran great for about 15 minutes. Then, when coming back from store, when starting the car again, it would start just fine for 2-3 seconds then just "shut-down". It would repeat this cycle again and again.

I also noticed my "check engine" light was on. I still have not hooked back up my oil sending unit, my reverse gear module, or my speedometer unit (Ineed to get a new one first.)

Should my car start and stay running with these still disconnected? Is there something else under the hood I might have inadvertantly unhooked, or some wire or unit I might have damaged? I'm baffled and hope someone can tell me how the t-shoot this problem.

 

I'm baffled and hope someone can tell me how the t-shoot this problem.
Check engine light means it stored a trouble code so go to a big parts store like Advance Auto, have them pull the coeds for free and they'll give you a print out of what caused the check engine light. Could be staving for fuel, when was the last time the fuel filter was changed? Is the fuel pump pressure within proper parameters? Failing fuel pump could make the engine start then stop. Get the codes pulled then go from there.