Hard Warm Starting Yanmar ysm8
I have a yanmar ysm8 with the following problems: It won't start warm (it starts instantly when cold) and it emits soot out of the exhaust. Also when I bought the boat it had no thermostat and started well when cold as well as after it was run (although after it was run, the engine was still cold due to the lack of a thermostat)
Here's what I've checked. I have replaced the injector, cleaned the mixing elbow, set the valves, checked the delivery valve, battery connections, etc. I haven't checked the compression, but suspect it's good because it starts very well when cold.
2nd, The soot. I'm assuming that the two problems are related. Soot comes out of the exhaust when you accelerate or are running at high throttle. I have hooked the fuel line up to good gas with the same results, so I expect the fuel tank isn't dirty. I tried some high sulfur diesel in the engine. With the high sulfur diesel the boat didn't emit nearly as much soot, but still wouldn't start while warm.
I'm suspecting a few culprits for the problem:
1. ignition timing might be off, I'm not sure because this is unlikely once again because it starts instantly when cold and the engine runs perfect.
2. Lack of ventilation in the engine room. I have a 26ft. s2. The only ventilation is a 3" vent elbow. Does this allow sufficient air flow. I know diesels require a lot of air and even more in my warm climate (I think)
3. My starting battery is a dual cycle 600??CA. Also my batteries are mounted in the engine room (which gets hot. I don't know if heat affects batteries.) Also The battery cables are standard 4 gauge??? they are pretty long as well. Once again I don't know if this matters because the boat starts instantly when cold.