Yanmar 6LPA-STZP2

[Twilite]

This is a thread with hopefully everyone that now has or has had the Yanmar 6LPA series 315hp engines to discuss problems and remedies with such a popular engine and to help anyone with problems they may be experiencing as well.



Currently the problem I am having is that when on plane, the engine abruptly just shuts down, throwing anyone on board forward like you just slammed on the brakes! Not good and dangerous too!



Sometimes the engine just sags down a little and other times it will completely shut down entirely but will crank and start right back up.



I have inspected the fuel side of the problem and did find that the input and output elbows on the racor were a little loose after noticing the vacuum gauge on top of the racor was falling off a little from the -3to4lbs required vacuum so that the fuel injection pump wont be sucking any air anywhere from the pick up tub in the fuel tank all the way to the injection pump.



Well, tightening the two 90's did not fix my problem but needed to be corrected regardless. So next, I disconnected the fuel line from the engine side of the racor and placed it in a separate 5gallon container of diesel to see if it did the same thing and it did. No change. So I was convinced then it was not a fuel problem.



So I started looking at and studying the wiring diagram in the back of the operational manual, I see that the motor (the injection pump) requires 12volts to run through the ignition switch. So I then placed a the positive lead from a voltage meter with a Min/Max recording on the source wire on top of the injection pump with the ground on the engine block, and noticed while on plane, that when the engine sagged a little, (lost power) the meter did show a drop in voltage to about 10.5vdc..So I will now be tracing the wires from the front panel cranking switch through the kill switch to the engine stop solenoid on top of the injection pump to hopefully determine along the way, where the 12volts is being lost. The kill button on the front panel opens this 12volt circuit to the fuel injection pump that shuts down the motor. So I will follow up with my findings and repost..