Diagnosing a Cranky Engine
Posted: July 1, 2012
If it matters, I always add the appropriate amount of fuel stabilizer at each fill-up. I have tried using marine-grade fuel (purchased at a marina), but it did not help. The fuel filter was recently replaced, but it did not resolve the problem. What could be the issue?
Fuel-injected engines can have this issue as a result of air bubbles in the injector lines expanding when the engine reaches operating temperature and is then shut down. Some airplane engines are notorious for this problem and have a special sequence of startup procedures for use when the engine is hot (sort of like your throttle pumping solution). You could take a look to see if any fuel lines are routed too close to the engine, exposing them to excessive heat.
Posted By: Harold Brandon On: 7/30/2012
Title: Hard starting when hot
Mercury has a flyer out that addresses vapor lock in IO's because of the high volume of alcohol in the fuel now. I would think the standard fuel stabelizer would add more alcohol.