Engine or Prop

[realem]

I have a 2gm20 and a three-blade kiwi prop. the boat just came back from the yard and when I put it in gear it is very rough and the engine stops with a lot of dark smoke.
help

[Pete7]

What work did they do in the yard?

Pete

[realem]

I had the bottom done and put my original 2 blade gori folding prop back on. It did not run right but the engine did run with a lot of chatter. I hauled again and put back the 3 blade kiwi prop. A lot of Chatter and the engine dies like load is to great

[SailingHarmonie]

Could be either… but sounds like you have something wrapped around your prop.

[realem]

Prop is perfectly clear and was clear in all circumstances

[realem]

I changed both injectors and still the same problem

[skipperpete]

If the yard only did the bottom paint and the propeller swap , it’s unlikely they introduced the problem with the black smoke and stalling so here are 2 possibilities that need to be eliminated in the troubleshooting process. The first is easy, check the position of the two decompression levers, amazingly the little Yanmar will run with one of those levers up and blow smoke like a Cuban cigar. The second is parasitic load from the alternator, yes it can happen although it rarely gets to the point where it actually stops the engine , instead , it can cause the engine to “hover” just above idle at full throttle and lay a film of soot on the water at the exhaust outlet so to eliminate this possibility just loosen the alternator belt or take it off and try for a start. The mixer elbow is always a suspect as is a blocked exhaust hose but these usually give a bit of a warning first rather than an instant problem.

[realem]

Thanks I will try both. I can get the engine to full 2500-3000rpm and it sounds great.
They never touched the engine but I will check anyway on the levers.
No problem loosening the belt for the Alternator.
I get plenty of water out the exhaust the smoke would indicate the the elbow is fine

[wyb2]

If it runs great in neutral your problem is almost certainly within or downstream of the transmission. Does your transmission have a clutch? Maybe the prop shaft isn’t turning at all and you are slipping the clutch until it manages to stop the engine.

[realem]

It does turn but I get a lot of chatter which can either be from the engine bogging down or the prop. I think it is a pretty straightforward transmission just put it in gear and go just pure linkage. I can disengage the shaft by un-bolting where the shaft and transmission come together and see what that does. It is a 2-cylinder engine. the shaft turns just fine in neutral

[realem]

Big Thanks for all the input someone might have the answer

[skipperpete]

Ok, so back to the propellers, is it possible that the wrong shaft key ended up with the wrong prop? Your kiwi prop has a really shallow keyway and a conventional square key can seriously damage the kiwiprop hub and perhaps lock up a blade..... one feathered and 2 on pitch ( if that’s even possible?) would certainly cause the symptoms you describe.

[Tin Tin]

So it runs fine in neutral. Did you try it in reverse?

[realem]

Same problem in Reverse. The blades seemed to move just fine after installation, however, I did have Gori feathering prop installed and a similar problem but the engine did not stall. A lot of chatter and shaft banging against the hull. I checked to see if there was any way the Gori blades can be installed incorrectly and I am pretty sure the cannot. So different prop similar problem but not bad enough to shut the engine down

[realem]

The parameter for the Kiwi is just at the edge of the engine capability. It was installed to give the boat more push against channel current under bridges