Yanmar runs backwards??

[heritage]

The engine, 2gm20f, had not been started in several weeks. After failing to start after several tries, I was about ready to crack the injector fuel inlets to see if that helped. Before doing that I tried starting one more time. Thinking back, my finger may have slipped off the starter button and I quickly re engaged the starter. Then all hell broke loose. The starter had a difficult time turning the engine over and the low oil pressure horn and light came on. After maybe 1-2 seconds I released the button and dove down to check the engine. Heavy smoke was billowing out. I'm thinking electrical short or a fried starter motor. But I'm almost certain the smoke was exhaust fumes. After some research I am convinced the engine did a little kick back and started a backward rotation forcing the exhaust fumes out the air intake. Later, I bled the injectors and the engine started and ran fine. Anyone ever hear of a Yanmar trying to run backwards?

 

[Alan Gomes]

The engine, 2gm20f, had not been started in several weeks. After failing to start after several tries, I was about ready to crack the injector fuel inlets to see if that helped. Before doing that I tried starting one more time. Thinking back, my finger may have slipped off the starter button and I quickly re engaged the starter. Then all hell broke loose. The starter had a difficult time turning the engine over and the low oil pressure horn and light came on. After maybe 1-2 seconds I released the button and dove down to check the engine. Heavy smoke was billowing out. I'm thinking electrical short or a fried starter motor. But I'm almost certain the smoke was exhaust fumes. After some research I am convinced the engine did a little kick back and started a backward rotation forcing the exhaust fumes out the air intake. Later, I bled the injectors and the engine started and ran fine. Anyone ever hear of a Yanmar trying to run backwards?

Yup. There have been a number of reports of this with the 1GM, at least.

 

[LakeShark]

It is my understanding (and I am no expert) that any desil can run backwards in certain conditions. You should never though let it do this for long as it is detrimental to the engine and has the potential to cause a runaway condition that could place your engine, boat, and crew at great risk. On large commercial vessels (power of course) a runaway is stopped by blocking the exhaust and choking the engine. On smaller boats it is less of a danger and the exhaust can't often be blocked easily. The important thing to remember is to have the engine completely stopped before trying to crank and monitor it at start up.