Generator Shut-Down Checklist
I went through this earlier this summer, and here are the easiest ways to figure out what is wrong with your generator.
1. Check the sea strainer to make sure there is nothing in it. If you find algae jellyfish seaweed etc., clean the sea strainer and re-insert it. Then detach the wrong water hose coming to the sea strainer and clear any obstructions in the hose. I did this by using the exhaust from my shop vac and blowing through the hose until bubbles came out from the intake.
2. If the generator is still shutting down, then check the impeller. You will need to remove the cover of the impeller and check the impeller if you find any veins have been broken, you will need to remove the impeller and then fish out all of the pieces of the impeller and make sure that you get them all. The easiest way is to put them on a paper towel and reassemble the impeller to make sure you haven’t missed any pieces a free-floating piece or two can clog the intake to the heat exchanger and caused the shut down. Put in a new impeller and cover it back up.
3. If the generator still will not run, check the oil level and make sure you have oil. When you start the generator have someone on board check to make sure exhaust water is coming from the generator outlet. If there is no exhaust water coming there is a block somewhere in the cooling water system. Troubleshoot that.
4. If the generator still does not run, the last check is for the two emergency shut off switches on the generator there should be one shut off switch that is located on the exhaust section. Remove the wires from the sensor, and test it with a multimeter to make sure it is working. In my case the sensor would be open until the system was running, and then it would shut off during normal operation and if it sensed high temps it would throw open shutting off the system. The only way to verify that functionality was to connect the two sensor wires directly together, removing the sensor from the equation. In my case that fixed the issue, so I ordered a new sensor and replaced it. The other sensor is the oil pressure sensor, which will probably be located right near the oil filter. Check that sensor as well.
In my case this solved everything. I wish I had gone through this in this order as that is the easiest way to troubleshoot things. Good luck!