Crusader problems

Hello all. I'll do my best to keep this short. The boat: 1985 Gibson houseboat with twin crusader 270's. The problem: I start both engines which fire up perfectly. After about a half hour, as I watch the tach, the port engine starts losing rpms. All of a sudden it starts spittin and sputtering and stalls. It will fire right back up, but misses terribly, then stalls. Then the starboard stalls and does the same thing. (this is all within 2 minutes). I then start the port engine again. It fires right up until I give it a little gas, then it misses again. At idle it sounds fine. With port at idle, I start the stbd. and it immediately shuts down the port engine! With stbd running at idle, I go to start port again, and it stalls the stbd! This goes on until it won't start at all. Then, wait a half hour and you can fire up both engines again and run the boat for about 15-20 minutes before the same thing happens. I need towed every time, unless I wait for a half hour. What I have done: (did this to both engines) new fuel pumps, new reman carb on port and a rebuild on stbd, new dist caps, new rotors, new plugs, new coils, new resisters. I then pumped out the 2 year old gas out of the tanks and refilled with new fuel. I've used non ethanol for years.&nbsp;<br>&nbsp; &nbsp; The questions: What is causing both engines to stall, once they get to operating temp, the way that they stall? Why is it affecting both engines the way it does? It is at a marina with a technician, but he doesn't know what's going on. I'll be glad to answer any other questions you may have.

By the way. Forgot to tell you. Prior owner deleted the points and installed pertronix igniters.

Check the o-rings on gas caps. They need changed almost yearly.
Have your mechanic remove the pertronix plates in distributors and look at mechanical advance mechanism. My bet is either they arena advancing at all, or springs rusted out and they are going full advance right off idle. Let us know what you find

I most certainly will. I do change O rings every year. I took the plates off the distributors last fall, and the springs and such are rusted, but appeared to be working. We'll check again.

do you think that's why both engines stopped and also why one would shut down the other?