I am having problems with my 2000 Chevrolet C3500, 7.4L truck. When I start my truck after it has warmed up it tends to flood itself out when starting. I have to crank the motor longer than usual and when it starts I get black smoke out the tail pipe. I have changed the Mass Air Flow sensor in the air tube between the air filter and the intake. there are two sensors I have replaced. 1. Mass airflow sensor 2. Air temp sensor....When I start the engine in the morning I dont have this problem. The times that I have this problem is when I have been driving for a while in town (stop and go) runningplace to place, this is when I have this problem.I would appreciate anyone's ideas on fixing this. I am going to change the spark plugs but I also need some advice on removing and replacing the distributor cap. It looks like it is behind and underneath engine components on this vortec 7.4L. I hope this chore is going to be easy....Thanks Andy

 

I see that the OP got no responses, and I've scoured the forum for threads with identical symptoms, but have found none.

If the engine has sat for an extended period of time, my van starts instantly if I start it with the fob (starting it cold without the fob is to risk flooding it). But if the engine has been running (10 hours, 10 minutes, or even 10 seconds) and I shut it off and then try to restart it (immediately restart it or even going into a store and coming out), the only way I can start it is if I stand on the gas as if clearing a flood. Even then it'll start rough, and lots of black smoke will come out the exhaust. If I try to drive away too soon, the engine will die, so I have to rev the engine, producing more black smoke until the engine finally runs smooth after about 30 seconds. After that, it runs very smooth and sounds great, but I have to put it neutral when approaching any stops, because the thing idles so high that it's burning up my brakes if I leave it in gear while decelerating.

Has anyone else run into this? What's wrong with my 2001 Express 1500?

 

OK, here's the update....

After looking through various other threads, I suspected other sensors, like the Engine Coolant Temp sensor, and, sure enough, when I took the vehicle to Advance to have 'em check for diagnostic codes, it threw a P0101, P0118, P0125, P0128 and another one to do with a catalyst something-or-other. The P0118 was the t-stat, and the P0128 was the ECT sensor if I remember correctly. Since I could blast heat in the cab, I assumed the t-stat was working, so I replaced the ECT sensor and....

....SUCCESS! No more flooded starts after it warms up, and no more popping it into neutral approaching stops and back into gear when the light turns green. Runs like a champ.