Yanmar 2GM won’t start.

[skipperpete]

Yesterday I went to start a reluctant 2GM Yanmar and thought it would be the usual well documented fuel problems that happen, air in the fuel, blocked filters or suction line, stuck injector pump plunger..... but not this time. The engine has excellent compression and cranks as it should but simply wouldn’t fire up or even attempt to spin faster, almost like the pull stop was on. After a fair bit of troubleshooting I found yet another way for a Yanmar to NOT start. After changing the fuel filters and bleeding the fuel system a couple of times I cracked the lines at the injectors and spun er over with the decompressor levers on and got a bit of fuel at both injectors. So tightened the pipes and tried for a start but not even a slight change in cranking speed so cracked the pipes again but left the decompression levers in the run position and was very surprised to get finely atomized fuel out of the front injector pipe nut, clearly the nozzle on the front cylinder was stuck open and the compression was forcing the fuel back out of the pipe union very energetically. I pulled out both injectors and was planning to free up the plunger on the bad one and clean what I thought was the good one but in fact both needles were stuck, one forever and the other I managed to free up but will be replacing both nozzles.
I suggest to NOT spin over a GM series Yanmar with the injectors out, I think there’s a reasonable chance the top half of the precom could be forcefully ejected..... I was initially considering doing this to check the spray pattern of the removed injectors but abandoned the plan.
PeteJ