Snapdragon III
New member
I am hoping for some good advice on getting my 2015 50HP Honda running properly. I bought the motor as part of the 13' tender on a larger trawler I purchased last year. It had been sitting for at least a couple years unused/broken down, in the tropics before I got it. It had a seized steering bar, and the high pressure fuel pump was corroded and seized, so it was not getting any fuel. I replaced those two parts and got it running pretty good, but I think I have a sensor related heat soak issue that I can't figure out. Here is a detailed description of the current problem.
After the work mentioned above, and new fuel, the motor starts and runs perfectly when it is cold. It will continue to run perfectly as it warms up, and everything is great. If you run it hard, then shut it down and park it at a dock, then come back about 30-40 minutes later, it will start right up, but if you give it more than about 1/4 throttle it will die immediately. If you let it run at idle, after 5-10 minutes, it will allow you to get up to 1/2-3/4 throttle before it dies, then another 5-10 minutes later it is back to running perfectly again. This is repeatable. I don't seem to be getting any check engine lights when this is happening. The conditions I was testing it in are winter/spring in Seattle area with cold water and air temperatures.
My theory is that one of the sensors is malfunctioning when it gets heated up past a certain temperature and gives an erroneous reading that causes the engine to die. It is not heating up from the engine running, but from the hot air inside the case when the hot engine is turned off. As the engine runs it draws cool air into the cover, and eventually cools the sensor off and everything works great again. The part I can't figure out is how to figure out which sensor might be causing this? I have not tried jumping the diagnostic port pins to flash error codes yet, but I assume I won't get anything that way since there is not check engine light? I did some googling for scan tools, but they all looked pretty expensive, of questionable quality, and require a windows computer which I don't have, so I would rather not go that route if I don't have to.
Any help you can offer would be greatly appreciated.
After the work mentioned above, and new fuel, the motor starts and runs perfectly when it is cold. It will continue to run perfectly as it warms up, and everything is great. If you run it hard, then shut it down and park it at a dock, then come back about 30-40 minutes later, it will start right up, but if you give it more than about 1/4 throttle it will die immediately. If you let it run at idle, after 5-10 minutes, it will allow you to get up to 1/2-3/4 throttle before it dies, then another 5-10 minutes later it is back to running perfectly again. This is repeatable. I don't seem to be getting any check engine lights when this is happening. The conditions I was testing it in are winter/spring in Seattle area with cold water and air temperatures.
My theory is that one of the sensors is malfunctioning when it gets heated up past a certain temperature and gives an erroneous reading that causes the engine to die. It is not heating up from the engine running, but from the hot air inside the case when the hot engine is turned off. As the engine runs it draws cool air into the cover, and eventually cools the sensor off and everything works great again. The part I can't figure out is how to figure out which sensor might be causing this? I have not tried jumping the diagnostic port pins to flash error codes yet, but I assume I won't get anything that way since there is not check engine light? I did some googling for scan tools, but they all looked pretty expensive, of questionable quality, and require a windows computer which I don't have, so I would rather not go that route if I don't have to.
Any help you can offer would be greatly appreciated.
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