The fuel shut-off selinoid is on the firewall side of the injection pump, on top. May have to remove air cleaner housing. This is on a 2040 with yanmar 4-cyl. Mine shorted out and would not start. Local dealer did not have one ,Alaska Diesel Electric sold Yanmar marine, so I was to get the part from them. I had a 940 that had same engine-drive train except without all lock-out sensors and safety stuff. I'm not familiar with the 920.You will need to check around the injector pump, there should be a solenoid if its not a mechanical shut off. It could simply be some junk got into it and a clean may fix it.
Depending on the type of setup it could be a 1 or 3 wire solenoid. If you can't find it, look for wires going to the engine around the injector pump.