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Message: <blockquote data-quote="SHEHAN_GIWANTHA" data-source="post: 22736907" data-attributes="member: 496236"><img src="https://www.thehulltruth.com/attachment.php?attachmentid=533821&stc=1&d=1432831825" alt="" class="fr-fic fr-dii fr-draggable " style="" />DefaultQuote:Originally Posted by REGMARINE26FS  View PostI have (2) 2002 F225 and vapor lock is my issue. along with many others reporting the exact same problem.and i was not suggesting the fuel loop back to the tank...i was suggesting a looped relief path, as it exists on my F225's today.One problem is that fuel being looped around a fuel pump causes the temperature of the fuel to rise. It can get quite hot actually. When the motor is at low RPM, and not using much fuel, then the looping of the fuel can become a problem with bad stuff happening. That is why Yams use a fuel cooler and in your case the lift pump that only runs for ten seconds out of every thirty seconds. The pump stops pumping for twenty seconds so as to minimize the temperature build up of the fuel. If there was only one fuel pump in the system, and if that pump was in the fuel tank or at the fuel tank, and if surplus fuel was routed back to the tank instead of simply being looped around a pump, the fuel would be much cooler. It would also get refiltered every time it came out of the tank. Not going to happen however because of integration issues. Early model motors dumped VST vapors into the intake system. Too much fuel vapor in the intake manifold causes an overly rich mixture. It can be so rich that the motor won't start or run. Just like an automobile being flooded. The more volatile the fuel, and the hotter the fuel becomes due to a pump working on it or the VST being in close proximity to a hot block, causes the fuel to boil. That boiling action send fuel vapors to the intake manifold causing the problem.Here is a diagram of an early Yam. Note that the VST vent line runs straight to the intake manifold. Later Yams have a different design that uses a shutoff valve and a charcoal cannister vapor recovery system.</blockquote>

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