black smoke at start, stop and full open

[Doug]

We are seeing a good gush of black smoke when starting (dark grayish/black) using adequate throttle. It starts right up, however. No exessive cranking needed.Also, after idling for 5 minutes, running up throttle and pulling shut off cable we get another blast of it.If we give her full open throttle while motoring (keep in mind we have already established our recently installed campbell sailer 3-blade prop is over propped and maybe the culprit on this one) she really puts it out. We do not see black smoke while motoring at 2,500 to 2,800 under normal conditions. Any ideas?Doug

 

[Gordon Torresen]

Black smoke

Your engine should start with no throttle. The design of the governor has the fuel setting for starting built in. Advancing the throttle when starting makes the engine try to get to the RPM called for by the throtle setting, hence a puff. Reving the engine and then pulling the stop cable makes no sense at all. Totally stopping all fuel from being injected into a turning engine deprives the cylinders from the lubrication provided by the diesel fuel. The fewer strokes made without fuel the better. You have the reason for the high speed smoke. Either turn slower or get the propper prop.

 

[Bryan C.]

Starting and stopping

I've heard some say that Yannies start best at about 1/2 throttle. I used to start with no throttle but tried 1/2 throttle and it starts much faster and easier. Agree with Gordon, don't kill fuel at high revs. I do rack er open for about 3 seconds when I shut down on the theory it helps blow out whatever carbon build up I might have accumulated. But then I let it idle for a few seconds before killing her.