B3300SU Running Issues

[Caden]

Hi all.
I was recently asked to help a friend who was having running issues with her Kubota B3300SU, hyrdrostatic model.
I'm a tractor man in general but I'm no expert mechanic. At least not compared to some of y'all here.
I took a quick look tonight and have some questions before I get in to it.

She was having intermittent no start, and by that I mean crank but no start.

After some research it seems that the safety switch on the rocker treadle works not by preventing a crank but by preventing the engine from starting while still allowing a crank. This is a new concept to me. Have I misread something here?

The treadle was sticking, not allowing it to return to neutral position. I lubed the linkage and the roller bearing thing that the treadle pushed on. That got the treadle returning. Still no start.

Noticed crank was slow. I jumped it with my truck and got it to crank faster and start. This was after neutraling out the treadle.

I thought all was all good...

After working it for about 25 minutes it began to die out slowly like it was starving for fuel. Tried to restart once, and had slow crank again. At this point I stopped and towed it back to the shed.

So as I question my next move I am wondering about the battery. Having a slow crank after running a while seems like a bad battery. I thought maybe I had a voltage drop that allowed the fuel shutoff solenoid to close.

What are y'all thoughts here?

 

[Russell King]

I would think it has a fuel issue like biological growth that is clogging up the filter and lines.

I would drain the fuel out of the tank through a paint strainer and see what comes out, if anything. Probably change filter or at least examine how the fuel flow is coming out to the injector pump. Does it have some type of lift pump?

 

[Caden]

@Russell King thanks for the reply.

From research I did I believe it may have a lift pump, but will have to verify in person.

I looked through the clear plastic fuel bowl to the cartridge filter, it looked clean. There may be another filter somewhere else on the machine.

The maintenance history here is anyone's guess.

Lift pump may be another thing effected by a weak battery, do you think?

 

[North Idaho Wolfman]

It has a mechanical lift pump so not effected by battery.

Use the WSM to trouble shoot any possible issues with the Stop solenoid.

 

[whitetiger]

Lift pump may be another thing effected by a weak battery, do you think?

Definitely not, as this model has a mechanical lift pump.
The controller dictates when the engine can run by controlling the shut-off solenoid.

A simple test is to remove the shut-off solenoid and run the tractor. If the running issue persists, it is totally mechanical, not electrical.

You can also check the fuel flow to the injection pump by removing the output hose from the pump and cranking the engine.
You could have a lift pump failure or a fuel flow from the tank to the lift pump restriction.