Engine stalling problem

[NoBozo]

Originally Posted by bigdog

Thanks MacShpMan for info about vent hose blockage. I have checked
hose at the top where it eixts the boat, however, have not checked
entire length of hose. Not sure how one would do that, or how to clean out.
Suppose I could run some plastic tubing down through the vent hose to check for obstructions, but then again don't want to force anything down
furhter if something is there....

I can relate to your friend's boat problems. I feel like I'm changing parts like clothes !

Talked to marine tech. this morning, he didn't have a chance to replace Distributor Cap or Rotor Friday because of backlog of customer repairs.
He's going to order parts Monday and work on boat Tuesday. After parts installed he said he'll take to nearby pond to test, best he can do under the conditions. I plan to be on that ride myself !

Marine Tech said it may be Carb problems again, but I reminded him the Carb about the complete Carb rebuild job he did 1 year ago. He said, Carb can still get gummed up with ethanol varnish, even after a short amount of time.

Explained to Marine Tech that I checked for Ignition Wire arching under the cover of darkness last night, and could not detect any arching from wires or Distributor Cap. He came right out and said 'It's not your wires, wires in a boat last forever' ! This seems very contradictory to what has been shared on this Forum. Then again, I'm not the Professional Marine Tech.
Honestly, the collections of knowledge and experience from members of this Forum, have been invalluable !

I find it extremely difficult to believe that the ethanol gas can be constantly causing my issues. Can't just be me ! Everyone would be having problems with their engines. Problem has to be something unrelated to gas.

Let me ask one last question..... If new Distributor Cap and Rotor, do not correct the problem, next replacement part may be the Coil.
Just a process of elimniation at this point....

How can you tell if you have a bad Coil? What are the symptoms?
Would symptoms be contant or intermitant, and it heats up?

Thanks agin.
Bigdog

Spark plug wires WILL deteriorate over time. Ten years of living inside that engine box with the heat will dry out the plug wire insulation and allow arcing...even if you cannot see it at night. Backfiring is likely an ignition problem. My educated guess is the distributer cap. Two screws loosened will allow it to be removed....without disconnecting the wires. Look inside the cap at the terminals around the inside rim. If the terminals look "Crusty", they can be scraped clean with a knife or screwdriver blade. The outside tip of the rotor can may also look crusty. Scrape them clean and you're back in business. Buy a new cap when you can scrape up the $45-50. I prefer Mercruiser parts rather than Sierra, even though Sierra is probably Half the cost.

Another possabity: If someone has been in the engine room, it's possable one of the spark plug wires came loose from a spark plug inadvertantly by being bumped into. I once actually had a spark plug wire dislodge itself from the plug during a backfire. At that time I was having plug wire crosstalking problems and at night, it looked like a christmas tree in the dark. If one leaky plug wire comes in contact with another leaky plug wire this will cause all manner of backfiring and rough running.

An ignition coil rarely fails, but when it does it usually happens when the coil gets hot and shorts out internally. When the coil is cold it may work fine.

BTW: A distributer cap for a boat with an inboard engine MUST BE Marine Certified. Automotive distributer caps are NOT acceptible.