I have a great old 1990 V2500 that all of a sudden went really rich. I drove to work fine, parked, came out at the end of the day, and it immediately flooded when I tried to start it up. Trouble codes at that time were: 15: Coolant temperature sensor, low temperature 34: MAP sensor voltage low (faulty wiring, now working fine) and I believe: 45: Oxygen sensor - rich exhaust Visual inspection of fuel injectors revealed a great deal of gasoline being consumed. Removing either fuel injector connector, the engine was able to start but obviously ran a little rough. It is apparent that the ECU is sending too much voltage to the injectors. Whether this is directly the ECU or if it's a failed sensor affecting the ECU remains to be seen. I assumed it's the MAP sensor because a low voltage is consistent with full-throttle operation, so it seems possible that's what caused the fuel injectors to open up. After replacing the MAP sensor and the wiring to it all the way to the ECM, I reset the ECM by pulling the battery for a while. I brushed the spark plugs, reconnected the battery, started it up, and ran it at about 1/2 to 3/4 throttle for a couple minutes to clean it out. I imagine considerable soot was in the engine after driving 3 miles home with a trailing cloud of black smoke. Probably not a good idea to operate it in that condition but I did what I had to do. The exhaust was good and black at first, but it cleared up after ~ 30 seconds or so. After releasing the throttle, the engine seemed to be idling normal and smoothly. Almost immediately when I attempted to drive, it shuttered, killed and was flooded out again. NO trouble codes this time. I theorize that there's something screwy with the ECM, maybe it needs to be replaced. It's sending too much voltage to the injectors. But ECMs expensive and I'm not convinced that's what's wrong. So at this point, it would help to narrow down: - Which sensors have the ability to affect fuel injection? - If these sensors are not to blame, what problems can cause these sensors to give an abnormal reading? ALSO: I swapped in some spare injectors which behave identical.