quote BillW:
Wow, that is a great find and good to know! While I have done that test many times on stern drive engines (propane works, too) and even on a couple of Merc four strokes with PLASTIC manifolds, I would have never considered that area, as a possible leak! Have you taken it apart yet, to see what the problem was?
No, I haven’t driven back out there since getting it running. I figured I would let the owner test it out for a few days to see if any further issues surface. This motor is around 10 years old and I believe 3 weeks is the standing record for longest time running. Hoping we set a new record!
The problem with taking it apart to check further is that I will have to launch my boat or borrow one to get to the rear of the motor and honestly, I am a bit weary of messing with it. I am easily 20 hrs into this thing. I am reasonably sure that either the intake manifold flange is slightly off square or has some defect on it’s face that is allowing the air to enter. The other possibilities are the plastic spacer or, less likely, the bracket supporting the choke. The electric choke isn’t shown in the picture I posted but it sits directly above the carb. Maybe it is bent enough to torque everything slightly out of line and allow air to pass by those paper gaskets.
