I have a 15 hp 2001 4 stroke Mercury outboard that I bought new and for years ran great. In the past few years I started to experience hard starting and sometimes the engine would die. I found some particles in the carb bowel and added an inline fuel filter and then found the cause after much frustration. The problem is the stock Mercury fuel hose from the tank is deteriorating internally and blocks the fuel flow almost completely. The inner lining has broken down to light brown particles that plug everything. The fuel hose I have is gray in color and I was unable to blow air through a 2 foot section. I replaced the tank fuel hose, primer bulb, fuel line to the carb in the engine (it was blocked also) and a new inline fuel filter. There is no way to tell the tank hose was bad by looking at it. You can push the check ball in on the engine side and fill a container to see if there are particles. The bad fuel hose does not seem to be well known as a major issue. The authorized Mercury dealer replaced the carb (expensive) and added the inline fuel filter when I had the engine serviced several times at the dealer and they did not find this issue. They recommended replacing the carb with a new and initially adding the inline filter every year. The problem came back in a short while and then I discovered the cause. The cold engine would start, run for 5 min then die and maybe start after an hour of trying. I hope this helps someone else!
PS - I don't understand why Mercury did not notify owners of this defect. My engine is registered with them when I bought it.
PS - I don't understand why Mercury did not notify owners of this defect. My engine is registered with them when I bought it.