Hard starting hot O-540

[Paul Klouda]

Greetings All,

I've got a ~450 hour factory reman O-540 that is giving me fits especially on hot starting. Example: Fly in and shut down after a 30 minute flight grab a $100.00 hamburger and then 30 - 45 min later fire up and launch. What was the usual start up procedure does not seem to cut it anymore. I would turn on master, boost pump, get positive fuel pressure, turn off boost pump, pump the throttle once or twice and then crank starter. In a few revs the engine would fire, and I would be on my way. Roll forward to now that does not work. Sometimes, I now have to throttle in and mixture to cut off turning the starter until I get the engine to catch and then quickly pull the throttle back and push the mixture in. Again, this is a normally aspirated engine, not fuel injected. I am not getting any back firing or other tells. The starter will sometime stall during a rev and I need to jog it to get it moving. I replaced the battery (Concord 35 extra crank power) no help, (have copper wires, Boggert) checked and tightened all the connections in the system and have new (less than 300 hours) on the mags and wires. Even starting cold using the prime can be a bit challenging. Once she's started I have had no problems.

Sorry to go on so long but I hope this paints the picture.

Any suggestions or input?

Thanks,

Paul