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Captaink73 · 09-05-2016, 08:48

Hey all,

I need some advice. I have an old Yanmar 2QM15 that's having an issue. I took it out recently and it took a bit of coaxing to get started. When I have the shifter in "warm-up" it seems to rev fine (although not as responsive as normal), but when I put it in gear I get minimal power and no rev even at full throttle. It's also putting out a lot of black soot out of the exhaust. The fuel is fresh.

I'm thinking it's probably the fuel injector pump or the governor. Any ideas?

**skipmac** · 09-05-2016, 09:03

I think black smoke usually indicates a very rich mixture, too much diesel or not enough air. Always try the easy, cheap fix first. Any change the air intake is blocked? Maybe a bird moved in a built a nest?

boatpoker · 09-05-2016, 09:13

or ..... very poor compression.

Captaink73 · 09-05-2016, 09:16

Air intake seems to be fine. There's nothing clogging it.

**skipmac** · 09-05-2016, 09:55

I am assuming from the context of the question that this is a recent and sudden phenomenon? If that is the case then I would look for something that could change suddenly and not a gradual issue like injectors slowly wearing or compression slowly getting worse.

captjcook · 09-05-2016, 18:28

Is the prop fouled. Will certainly yield black smoke and low revs...

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lateral · 09-05-2016, 18:47

Exhaust mixer elbow clogged-clean soot out
Stuck/varnished up injector - check each spray pattern

gypsea67 · 10-05-2016, 07:22

Check prop. I had similar situation and prob was covered in barnacles.

Cadence · 10-05-2016, 07:59

Quote:

Originally Posted by skipmac

I think black smoke usually indicates a very rich mixture, too much diesel or not enough air. Always try the easy, cheap fix first. Any change the air intake is blocked? Maybe a bird moved in a built a nest?

Or Mud Daubers, wasps, They will build anywhere quickly. Maybe something as easy as they have obstructed the breather for you fuel tank.

Best of luck, I hope it is simple.

reed1v · 10-05-2016, 08:35

Your head gasket is blown and maybe the piston rings. That is if you are lucky.

**skipmac** · 10-05-2016, 08:48

Quote:

Originally Posted by captjcook

Is the prop fouled. Will certainly yield black smoke and low revs...

This is a very strong possibility.

coastalexplorer · 10-05-2016, 10:34

Remove the injectors and take them to where they rebuild them to have them tested.

IF they are Bosch and they sent jets of fuel in four directions like a cross they need to be rebuilt: so they spray a mist instead. I had to do this to my Volvo. It would not start before injector rebuild. fired on the second revolution after. So start with the injectors before worrying about the pumps.