You had an issue before unplugging the ECT. That condition probably was getting worse and you just think unplugging the ECT made it worse.

Did you check the fuel psi and regulator as suggested above ? Loading up at idle / low speeds and engine running better or normal at high speed is the condition this will create.

my guess,,pull the injectors and have them checked,1 or more are dumping fuel.

He did.
Post #3 http://www.offshoreonly.com/forums/g...ml#post4337915

well who actually did the work?

starting to think engine may be worn out,,compression test and leak down is in order.

Sounds like a wireing harnesses issue if you have replaced everything else. I would have thought crank or cam sensor, or the injector driver in the MEFI, but you eliminated those.

Ok. more info. I checked most wires to ecm J1 and J2 plugs. Wiring to distributor, coil, coolant sensor,MAP sensor, throttle position sensor, Intake air temp sensor, hot wire, switched hot wire, and grounds, injector hot and ground wires and all test ok. Here is a interesting development.. I borrowed a scanner from a friend and it would not detect mefi3. Its said check connector. Thought it may be s fluke. So I caved in and took it to a local boat repair business yesterday. Guess what....their scanner would not detect the mefi3 either. His fear as well as mine is that the mefi3 died a sudden and horrible death! Everyone seems to agree that me unplugging the ECT sensor had nothing to do with it but boy what timing. Need suggestions on who to send this mefi3 to to be checked to see it it is shot or not. By the way, the engine ran 100+ before the incident and 100+ 2 hours after the incident so I doubt if it is worn out. It also started a couple of time in the barn but now with no injector pulse, it you want it to start it takes starter fluid. Also, to answer some of your questions, I had the injectors cleaned first thing at the same place that did it for me 5 years ago an the same boat. Fuel pressure is the same as it has always been, may have been some of my loading problem but not my current problem. Thanks to all for your imput. At this point I am sending this mefi3 somewhere just need suggestions. I have talked to Eddie at Young Performance and he was very helpful. I don't think he can check just the computer without it being hooked to the boat but I will reconfirm, He is in Nashville which is only a 3 hour drive for me. Again .....thanks.

I can check it out. I have a test harness that we can plug it into and see if it's any good. I also have a few Mefi 3's if needed. Hopefully, yours isn't password protected.

I think I saw you on the Ohio when this happened. I thought you were on fire at first with the amount of black smoke you were dumping out.

Thanks again to Young Performance. Just talked to him on the phone again. To correct an earlier error...he can indeed check the mefi3 without the boat. He has the test leads to tell me what is going on with the computer and to do whatever is necessary to get me back on the water. I will be sending him my mefi3 possible today if I can get the time.