Just for reference the only website I was able to find that discussed troubleshooting of the ETQ diesel engines was
Practical Machinist.com. They really dove into all sorts of possible problems with a members generator engine that wouldn't start. I had a good time reading all the things they threw out for the guy to check out. It came down to the fuel pump unit in the engine being frozen up for some reason. The fuel pump is simply bolted to the engine and it is connected to the hard line that you can follow down the side from the top. It is actuated by an internal cam that presses the pump in and a spring pushes it back out until the cam pushes back etc. His spring and pump was seized up for some reason but once he shot it with a heavy dose of WD-40 it freed up and worked just fine. He has some nice pictures which have the components labelled which helped me out a little since my labels aren't so easy to read anymore.