Diesel Mower Advice

[steveh_131]

I was hoping some of you mechanically inclined folks could give me some advice on this.

Got a Kubota ZD28 ZTR Mower. It only has around 500 hours.

It would get up to high throttle and then when I started the deck, it bogged down and died.

Now it's worse, wouldn't even idle without dying.

Today I checked the air filter, seemed fine. Fuel filter was a little worn out so I went ahead and replaced it. Primed the pump and started it. Died pretty quick. Primed it again and it had to crank a lot before it fired, but it keeps dying right after it starts. Lots of smoke is coming out the tail pipe. Can see the fuel filter about half-full with fuel.

I do alright with gas engines, but I'm not very experienced with diesel. Where would you guys start in troubleshooting this? It's had issues with corroding electrical, but I fixed those at the battery recently. It seems like all the smoke would rule out a fuel delivery issue, wouldn't it?

Appreciate any advice you can give.

 

[96firephoenix]

idk about diesel specific, but this is precisely what my gas mower was doing when I took it out for the season... turns out the fuel drained into the crankcase. drain your oil (you'll get upwards of 2x the amount usual to the crankcase), then add the recommended dose.

case in point - I got .5 gal (4 pints) of oil/gas mix out of my mower. spec fill is 1.5 pints.

 

[steveh_131]

Thank you for the idea.

Dipstick shows the oil a hair below the full mark - should rule out the fuel in the crankcase right?

 

[Mr. Habib]

Injector bad? Fuel pressure ok?

 

[HHollow]

First off I would check the deck for resistance. Maybe a mechanical problem there. My B7100HST Kubuta is underpowered and would not like a mower deack with a stuck bearing.

 

[17 squirrel]

What do you mean by primed the pump ?,
When you changed the FF did you bleed off the injector pump ? Did you also Bleed the injector lines also ?

 

[steveh_131]

Injector bad - Any good way to test this?
Fuel pressure - The filter fills up to about 2/3 high pretty quickly. Should I pull a line after the pump and see how it flows?
Deck resistance - This was my first thought, but it's doing it with the deck off now.

17 squirrel - The service manual says to hold the key in the "on" position for 30 seconds to push out air and bleed the lines after changing the filter. I'm guessing it has some sort of automatic bleeder down the line somewhere?

If it is starved for fuel, would it be spitting black smoke out of the exhaust? It seems like that would indicate that it is starved for oxygen, but the air filter is clean... anything else to check on this front?

Really appreciate the help, guys.

 

[17 squirrel]

The smoke most likely is just unburnt fuel from the engine not running on all cylinders.
I would crack then injector lines loose from the injectors and spin the engi e and see if all cylinders are purged of air. Spin engine over until you get nothing but fuel from each injecfor. You just need to break the lines loose a little and you can close them one at a time as the air purges out and you get nothing but fuel as you spin the engine over.

 

[96firephoenix]

Thank you for the idea.

Dipstick shows the oil a hair below the full mark - should rule out the fuel in the crankcase right?

Not necessarily.. that's what mine read with .5 gal. of oil/gas mix and with 1.5 pints of oil.

Same reading with categorically different amounts of fluid. o.0

 

[steveh_131]

For anyone else who comes across a similar issue:

These models have two fuel filters. One is before the fuel pump and one is after. The non-obvious one is below the engine. The manual says nothing about this second fuel filter, so it has never been changed and it was clogged tight.

Thank you all for your help and advice.