I have seen many posts regarding the engines not running properly or dieing out etc. One guy told me that he had issues and did all kinds of things to get it to run Point, and so on. The problem with it was found out. It was a pinched fuel line due to the routing of the hose. He fixed that and it ran well. My 1818 has the onan 18HP Preformer. Runs well but I went to the electric fuel pump due to the constant sludge in the tank that you cannot change and I added a filter for that and it's been fine. The other issue I have is the forward and reverse on the right side not working and I have not gotten to that as yet. During my first days of having this I had starter issues. On these you have to pull the engine and slide it out the rear. You may know all this. I bought a new starter and no change it would catch properly So out the engine came. New ring gear and all that stuff. What I noticed while doing all this was a crack in the casting where the starter bolts to. Who would have thought that and had that welded up given all my skills and master of none. Since then no real issues. But the forward and reverse fails and I hope it's not a hyd motor/pump etc. Hard to find. Sorry for the long note but it haunts me. Just some odd things that have happenend that no one looks for normally. Good luck!!