Komatsu Diesel dies

JerryCPP(WA) · Nov 23, 2019

I just got a PC05 Komatsu excavator. It ran well to load and unload and into shop for checkup. I drove it less than 100 feet to try it, and promptly killed the engine. Now it won't start. Turns over, full of fuel, filters clean, fuel pump pumps a little fuel to injector pump. Crack the throttle and it turns fast, maybe even starts and runs about 5 seconds, dies, then turns over slow. Let it sit for an hour, and again it turns over fast. After a lifetime of gas engines, this is my first diesel, and I don't know where to turn next. It's got fuel, it's got air. Many of you have a lifetime of diesel experience - what next?

Shortrun · Nov 23, 2019

(quoted from post at 17:12:19 11/23/19) I just got a PC05 Komatsu excavator. It ran well to load and unload and into shop for checkup. I drove it less than 100 feet to try it, and promptly killed the engine. Now it won't start. Turns over, full of fuel, filters clean, fuel pump pumps a little fuel to injector pump. Crack the throttle and it turns fast, maybe even starts and runs about 5 seconds, dies, then turns over slow. Let it sit for an hour, and again it turns over fast. After a lifetime of gas engines, this is my first diesel, and I don't know where to turn next. It's got fuel, it's got air. Many of you have a lifetime of diesel experience - what next?

Does it have a water seperator? That needs to emptied. Some tractors have 2 fuel filters, worth checking. I'm newer to diesels then you, so thats all i have.

jaoneill · Nov 23, 2019

Sounds like a fuel issue. Not familiar with that particular breed but, do you get smoke? If not, you're not getting fuel. It probably ran on what was in the injector pump. You say that there is a "little" fuel getting to the injection pump; you might want to disconnet a line to determine how much. The lift pump should feed the injector pump a pretty decent stream of fuel. Sometimes diesel tractors will have an inline screen ahead of the filters, worth a check.
Another possibility is that there is a bacterial infection in your fuel tank. I had that happen once with a tractor that sat unused for awhile. Bloody slime created by the bacteria will plug a filter quicker than I can type this.

Shortrun · Nov 23, 2019

Just FYI
https://www.ebay.com/itm/Komatsu-PC05-6-Filter-Service-Kit-Air-Oil-Fuel-Filters-W-3D72-2-Eng-/162431201829

Dieseltech · Nov 23, 2019

On some older Komatsu diesels with Diesel Kiki/Zexel injection pumps there's a fuel inlet banjo bolt with a removable screen inside that could be plugged. Ones I've seen were at the supply pump inlet, fuel was to the banjo, but very little at the outlet as the screen was nearly plugged. The screen threads into the bolt end, and can be removed for cleaning. Not sure if yours has the same bolt though.

tomtinker · Nov 23, 2019

Have you checked for a fuel line shut off valve?

showcrop · Nov 23, 2019

The nice thing about diesels is that it is nearly always the fuel. What does "fuel pump pumps a little fuel to injector pump" mean?

JerryCPP(WA) · Nov 23, 2019

Thank you for the replies. Fuel tank clean, no bacteria. Fuel filters clean and passing full stream. Full 1/4" stream at injection pump only goes out and inch or less, but bleeder screw on top of banjo bolt at injection pump squirts a .060" stream 4-5 inches. This is only a 3-cylinder 12hp engine, so shouldn't need a huge volume of fuel. Long ago I watched a mechanic bleed the injectors on a Perkins 3-152 after replacing the injector pump. Is that my next step?

jtwat · Nov 23, 2019

I have a PC27. If yours has a key shut off, check the fuel shut off solenoid. It is attaced to the injector pump and has two or three wires going to it. If it is sticking or bad, it will not let fuel into pump.

JerryCPP(WA) · Nov 23, 2019

Smoke as it turns over is thin and brown/gray. Throttle position idle - turns fast. More throttle, turns slow.

JerryCPP(WA) · Nov 23, 2019

The key switch is 3-position. Left = one red indicator light comes on, I assume that's the preheat. Center off = engine still runs. Right = alternator on? Full right = starter engages. This thing is about 30 years old - all decals and labels are long gone or under a lot of paint. There are 4 red indicator lights, three of which are dead. I'm not the first one there with the wiring but there is no solenoid in the fuel system; you push the throttle lever past idle to shut it off. No luck on operator's manual or repair manual; PC-05 has been superseded by PC05-3, -5, -7 and I have no idea what changes the dash numbers indicate. I think I may have an orphan.

tomtinker · Nov 23, 2019

Lossen the fuel line at one injector is the first thing I would do to check for air or fuel while cranking.

caterpillar guy · Nov 25, 2019

Sounds like it is not bled well enough. My welder has a kubota engine. I changed fuel filters and had a hard time getting it bled so it would run good. Called miller about it and they told me it was not bled well enough. So went back and bled it some more and has worked fine since.

JerryCPP(WA) · Nov 28, 2019

Thank you, Caterpillar Guy. That seems to be the consensus. I have a new fuel pump on the way; when it gets here and is installed, I'll bleed the lines from the tank all the way to the injector pump, and then the injector lines at the injectors.

Komatsu Diesel dies

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