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I have a Scag Turf Tiger with the Kawasaki 29hp DFI engine. 1700 hours. Problems first started when I would get into some thicker grass, engine would start bogging down or missing and black smoke. I would slow down to a crawl to get through it. Sometimes it would do it and other times it would not. Now it has gotten much worse to the point that it has stalled out the mower. I started with simple things like new air cleaner, correct plugs, and fuel filter. Problem continued to worsen. I just replaced both coils and both are firing. One thing it does is when it starts this it emits a black smoke that almost burns your eyes. While mowing, I have pulled the plugs and they are black. Also I pulled the plugs when it was just at an idle and they were wet with gas. Compression checked at approximately 100psi both sides. Seems like a fuel problem. Please help

Sounds like a valve problem. I don't know that engine is it ohv?

Over head valve with digital fuel injection which means that it has an electric fuel pump, sensors and an electronic control module that meters fuel flow.

Wow that's a lot of tech for a small engine... Personally sounds like the valves are out of adjustment but there is aparently a lot involved there

Mad Mackie said:

Over head valve with digital fuel injection which means that it has an electric fuel pump, sensors and an electronic control module that meters fuel flow.

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So do you think It could be the electronic control module that is the culprit? Seems like it is definitely getting way to much fuel.

Unplug one spark plug wire and try to start. See what happens. The try it again but with the other wire unplugged, and that one plugged in......

Disconnect the battery positive, disconnect each electrical plug one at a time and inspect for dirt and corrosion, reconnect the plugs and the positive battery cable. While you are looking over electrical, make sure all cables and connections are OK for example where all the grounds are on the engine mounting bolt. Do any panel lights flash which would indicate engine fault codes?
Is the charging system putting out 13.8-14.5 VDC with the engine at WOT?
Have you ever replaced the PTO clutch?
Is there fuel dilution in the engine oil?
100 PSI compression is fairly low for these engines.
Mad Mackie in CT

Fish said:

Unplug one spark plug wire and try to start. See what happens. The try it again but with the other wire unplugged, and that one plugged in......

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I have checked and cleaned all connections. I said 100 psi but it was actually about 110. I can check that again though but pretty sure that was it. Yesterday I tried to start it for about 15 seconds. Would not start. Pulled plugs that were soaked with what smelled like gas.

A digital fuel injection engine uses electrically operated fuel injectors that are controlled by a electronic control module. There are sensor inputs to this control module that tell it what condition the engine is operating in. By condition, I mean the engine RPM, operating temperature, engine load, and possibly more. You may have a bad sensor(s) or a bad control module. It could be something as simple as a disconnected hose to the intake manifold for the manifold pressure sensor. Depending on the model of your engine, these systems vary in complexity due to system design improvements and stiffer emissions standards.
I recommend that you contact a local quality Kawasaki engine servicing dealer to start the process of resolving your engine problem before any more engine damage occurs. With 1,700 hours on this engine and a possibly a sizable service bill to resolve the problem, you may want to consider a direct repower of this machine. Check out on line places like Small Engine Warehouse, Tulsa Engine Warehouse and others for the price and availability of repower engines. Your engine is a horizontal crankshaft engine and with DFI probably isn't old. Fuel dilution of the engine lube oil can cause serious internal engine damage and quickly lead to engine failure.
I haven't dealt with any DFI engines in my limited service shop, but I've worked with EFI on many cars/trucks over the years.
Mad Mackie in CT

Well then, take it from there, disconnect the fuel line from the fuel pump, and aim it into a can, if the engine has been running flooded then it should finally start and run good for a few seconds until all of the fuel burns off.

But I am serious about the spark plug wire thing, try that secondly....

Adding to the direction that Fish is heading, there is an engine mounted "Y" harness each leg of which connects to the ignition coils. In these legs there is a diode installed and the purpose of these diodes is to prevent cross feeding of the primary coil voltage when the engine is shut down either by the key switch or the safety control module on the machine.
When the key switch is in the off position, it grounds this engine harness and shuts the engine down.
If either diode in the harness is shorted, then some strange problems can happen and get worse on a DFI engine.
Key switches are known to go bad as the coil primary voltage can be 200 Volts or more and this voltage is present in the key switch at all times the engine is running. The key switch can develop and intermittent problem and cause other running problems which react differently on a DFI engine as compared to a carburetor engine.
Just some thoughts!
Mad Mackie in CT

yeah, the unplug thingee is a good tool too, as I have seen a lot of twin engines run pretty good until they get into some grass, and it turns out that the engine is only running on one cylinder.

The greatest thing about my suggestion, is that it is free to try/test, and it narrows down the problem quickly...

Fish said:

yeah, the unplug thingee is a good tool too, as I have seen a lot of twin engines run pretty good until they get into some grass, and it turns out that the engine is only running on one cylinder.

The greatest thing about my suggestion, is that it is free to try/test, and it narrows down the problem quickly...

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I totally agree with everything you are saying. Both coils are new and both are firing. I have done this already. My question is if I pull the fuel supply this will not affect the dfi correct? They will still inject the same until the full runs out am I right? If so whatever is telling them how much fuel to inject is sending false info.

Mad Mackie said:

Adding to the direction that Fish is heading, there is an engine mounted "Y" harness each leg of which connects to the ignition coils. In these legs there is a diode installed and the purpose of these diodes is to prevent cross feeding of the primary coil voltage when the engine is shut down either by the key switch or the safety control module on the machine.
When the key switch is in the off position, it grounds this engine harness and shuts the engine down.
If either diode in the harness is shorted, then some strange problems can happen and get worse on a DFI engine.
Key switches are known to go bad as the coil primary voltage can be 200 Volts or more and this voltage is present in the key switch at all times the engine is running. The key switch can develop and intermittent problem and cause other running problems which react differently on a DFI engine as compared to a carburetor engine.
Just some thoughts!
Mad Mackie in CT

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i believe you are on the right track. It started but then just kept getting worse. It is a good engine IMO and I truly believe there is nothing wrong internally. It is so frustrating and I cannot wait to get this problem resolved. This is my last season in the mowing business so getting another machine is not an option.