After about 45 minutes of running on the water, the motor surges and bogs and continues that way until the motor cools down.
So far, things that I have done are rebuilt the fuel pump. Then I changed it out to the modern style which seemed to solve the problem, but then it came back.
Vents were open on the fuel tanks although both days it was at the 100 degree mark outside.
What else do I check? Most things I have read point back to the fuel pump, but I have done everything I can with that.
I'm not mechanically experienced, so although everything I have done on this motor I have done myself, it is with lots of coaching and I have avoided things like rebuilding the carbs because it is complicated on this motor and I will never get it right. Unfortunately, there just aren't many boat mechanics in my area and even less that will work on these old motors.
I had that problem also and found that the drop leg filter screen inside the fuel tank was partially plugged with years of gunk. If memory serves me the '66 was first generation of the CDI which was prone to problems when the heat was on. There are ways to correct this problem.
Bruce I changed the coil to the auto one you recommended a while ago. I didn't have this surge bogging issue at all last year. It started up at Shasta. The problem would have to be on both the old and new fuel pump then. I went to the more modern style fuel pump which seemed to give me better acceleration than the old style.
Cal-- Thanks, I have points ignition. i am going to have to check it again. The problem if it is a fuel tank is one is new and one is old and it seems to happen on both.
Have you tried to have someone look at the fuel line primer when the engine is doing this? See if the bulb is collapsed ( tank not venting or bad check valves ) also try having someone squeeze the bulb aggressively when the engine is doing this - to see if it clears up momentarily.
We found that a cheaper brand bulb had deteriorated from ethanol fuel and the inner ball was coming apart when we cut the outside off to look. A small piece had torn loose and was lodged in the line. New quality line and problem solved. We also found The neighbor's gas connection wasn't a matched set and was sucking air... to the point I could never get the ball to firm up. Each ends were different brands of aftermarket. Hope you nail down a simple find... maybe even a fuel line crack that is slight near a stress point. Just my amateur 2 cents. I want you to know I am no mechanic, nor authority on the matter. Just want a fellow boater to fully enjoy their rig.
Thank you. The fuel line and bulb were brand new OEM a year and a half ago, so while I don't think that is the problem, I bought another one just in case one of the valves went bad.
I have learned a lot since I got this motor. I didn't no the difference between a fuel pump and distributor when I started and I thought I had it dialed in pretty well, but this problem has just eluded me. And with no way to really test it without a two hour drive, it takes a long time to diagnose. Next trip isn't until the end of October.