So i have to share this information for anyone else out there that just might be having the same issue that i had with my 2000 Evinrude 4 stroke 50hp. I picked this motor up as a project for 200 bucks. It was in rough shape, missing pieces, rust, etc.... I rebuild the whole motor, using the shop manual the whole way. I put roughly $400 worth in parts to get it into running shape. After putting on the last part, i hooked up my remote start and battery and fired her up. She purred like a kitten, for about 10 seconds, then it just ran horribly rough. It would surge and stall, surge and stall, repeat, repeat repeat. I checked for fuel, spark, and compression. I had them all. I checked fuel pressure, it was good. I checked my injectors and cleaned them, and did a spray test on them. Everything checked out good. I started running checks on all the sensors and they all checked out. Just for the heck of it, i started it up and unhooked the MAP sensor, walla!!! Engine was back to purring. I plugged the sensor back in, back to running rough. I would get a beep code when i unplugged the sensor, but never got the code when it was plugged in. Anyways, long story short. If your motor is running like complete crap, check the dang MAP sensor. It took me about 25-30 hours of tinkering to finally find the problem.
