2005 Mercury Optimax problem?

Question

Ok guys, after replacing the powerhead gasket here are the results of the DDT test and pressure tests...

The only faults were SmartGauges that I didnt have hooked up like fuel, oil, tach, pitot, etc. an overreving, an overheat, and also a TPI Circuit to low. When he did the misfire tests (shutting down the cylinders one at a time) the #2 cylinder didnt do anything. So, he switched the plug wires...didnt fix it...switched the coil...didnt fix it...switched the coil driver...didnt fix it...switched the fuel injectors...didnt fix it...switched the air injectors...didnt fix it...took the pulse fuel pump apart and replaced the diaphram and gaskets...didnt fix it...tried new plugs...didnt fix it...all the continuity tests were good also. We did notice that the #2 fuel injector was perfectly clean but the others had black carbon on them...it's like there is too much fuel being dumped into the #2 cylinder and it's fouling the plug. So, I'm back at square 1!!! Still only reving 4950 RPM at WOT

Answer 1

If your injector is washed off with fuel,you could have either one of these problems.First is a leaking head gasket and second and much more costly is a chipped or broken reed valve.These are the only things that would wash off the injector.Good luck.

Answer 2

If you did all of this and the engine is running smoothly,  you may have a propeller that has too much pitch.   This engine should easily turn about 5600rpm at wot.  Try to find a local prop shop or marina that will let you test a couple of different props with lower pitch sizes to see if one of them corrects your problem.   If so,  you can have your current prop re pitched or buy a new one and keep your old one for a spare in an emergency.

Answer 3

One suggestion- borrow a different power pack that is working and try it out on it. At least it would tell you if that was the problem or not.