Re: engine bogs down after warm up?
I assume if it's been in for tuneups and run in test tanks for 5 minutes then it's been compression tested and spark tested, impeller changed, etc. So we'll skip that for now.<br /><br />Take the shroud off and take it for a run back and forth in front of the dock. Bring it up to "misbehaving" status and do some troubleshooting right then.<br /><br />You could have an exhaust leak that's filling the shroud with exhaust. After 15 minutes it's starved for oxygen. Does running it without the shroud make it run better?<br /><br />Is it getting hot? Make sure it's as cool after 20 minutes as it is after 10 minutes. The motor should be up to operating temp and the thermostat open after 10 minutes. If the motor keeps getting warmer after that then you have a cooling problem. Hot is serious. If it's getting too hot to touch then you're hot horn is broken and you're killing the motor. Shut it down!<br /><br />Ignition parts (dying coils, powerpacks, even cracked spark plugs) can start misbehaving after warming to a high enough temperature and holding there for a bit. After the motor gets warm and begins acting up and won't do anything but idle, start pulling plug wires one at a time. If you pull a plug wire and the motor doesn't run any different then you've dropped that cylinder. Bring along a bolt that you can fit into the spark plug boot. As you pull plug wires, push the bolt into the plug boot and hold it close to the motor block. Look for good spark. Wear rubber dishwashing gloves and keep clear of the flywheel while doing this.<br /><br />Post results.
