1GM 10 Yanmar Running backwards

Spill point too early. Adjust the injector timing. Or the bores could be very worn and it's firing on engine oil before the fuel is injected, sending the piston back down before its reached the top. But if it was running on engine oil it would run away uncontrollably probably.
 
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Spill point too early. Adjust the injector timing. Or the bores could be very worn and it's firing on engine oil before the fuel is injected, sending the piston back down before its reached the top. But if it was running on engine oil it would run away uncontrollably probably.

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No, no they can all do that sir (Well mine certainly has done once or twice). It happens if you release the starter just before it fires, the piston 'bounces' off the compression and starts to run in reverse. Smoke comes out of the air intake and if you don't stop it damn quick the pump impeller melts.
It may even be that the alternator running backwards will empty all the electric out of your batteries and you will end up with bilges full of loose electrons.
 
apart from the air cooling alternators will run in either direction without leaving any electrons in the bildge. Just a thought.
 
Dunno, but it is a fact that they can.
More importantly, the way to prevent it is to always give it at least half throttle when starting it. i.e. it is only known to happen if trying to start it with no throttle.
 
Just remember forwards is backwards and vicky versa and don t stick your head in the engine compartment /forums/images/graemlins/laugh.gif /forums/images/graemlins/laugh.gif Might need a new impeller after a minute or two..
 
My 1GM 10 did this once in 7 years of starting it with no throttle as it seems to start better that way, my biggest worry would be it not picking engine oil up from the sump as the pump would be running backwards and burning out the air filter foam.

Pete
 
No, feel free to disagree. The was advice given to me by Yanmar's European service manager who probably has as much experience of these engines as anyone.
I ran a 1GM10 for several years without experiencing the phenomenon, and I invariably started the little love without any throttle. If it happens regularly though I would suspect the injection timing is out.
 
I've had this a couple of times, when hand-starting them. Seemed to run quite convincingly in reverse!

I'd put it down to bad luck if it happens. If it's a regular problem, then look into it. If it just happened once, don't worry about it.
 
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