Diesel runaway

[RAD88]

Is it possible for a clogged fuel filter to cause the engine to runaway? I have a 1977 Yanmar YSB-12 1 cylinder diesel which had worked perfectly for years and today on the second time running the engine it started to run away. After that i could not restart it. The engine would always start in 1 sec on the first try.

 

[Mark Maulden]

Well, your engine is about the same vintage as my volvo. Runaways are caused by uncontrollable fuel flow into the combustion chamber. So, 1) broken governor, 2) broken governor linkage to high pressure fuel pump, 3) hole in fuel lift pump diaphram letting fuel into the crankcase getting past the rings. This reply is based on my engine design. What is your oil level? What happens when you tryto start it?