Changed out fuel filter and now tractor won't start

[fruitcakesa]

I was having some intermittent power loss lately where the engine would just rev down and stumble along for a few seconds and then regain power.
I changed out the fuel filter and cleaned the fuel strainer.
Pumped up the filter till it was hard to push the pump, filled the fuel strainer and then started it.
It ran for a minute, then began to stumble. I was able to keep it running and started to drive it back to the shed when it stumbled again and then quit.
I have not been able to restart it since.
It will crank fine but no start.
I opened the fuel cap in case that was the issue but no go.
I am stumped [being relatively diesel ignorant].
This is a real problem with a winter storm on the horizon.
Any help is greatly appreciated

 

[Tx Jim]

My M7040 is one of the easiest diesel powered tractors to change filter & bleed the air that I've owned. By chance is fuel shut off at water separator housing? Have you checked for good fuel flow from tank? I once owned a M4900 that had fuel problems. Local Kubota service manager advised me to check for clogged screen in fuel shut-off valve. Sure enough tiny white screen was clogged. I cleaned screen & solved fuel problem

 

[leonz]

Is your mule a direct injected diesel or an indirect injection diesel?
Its most likely an indirect injection diesel from what you have described.

If it is an kubota indirect injection diesel it still has air in the fuel lines and
it must be bled out.

If you have metric tools it is easy to do if the indirect injection fuel pump
is on the right side of the motor and near the front of the upper cylinder block.

The steel fuel line at the very front on the injection pump has a banjo bolt on it
with a drain port and you need to loosen it to allow the air in the fuel lines to
exit the injection pump.

You only have to loosen the banjo bolt 1/2 a turn or so to open the drain port and
manually pump fuel through it to bleed the air out of the fuel lines.
When that is done tighten the banjo bolt back up using a light touch as the copper
washer under the head of the banjo bolt is very thin and can be damaged and cause
a fuel leak.

============================================================

If your mule had an direct injection diesel it would have fired and stayed running after you
replaced the fuel filter.

 

[fruitcakesa]

Is your mule a direct injected diesel or an indirect injection diesel?
Its most likely an indirect injection diesel from what you have described.

If it is an kubota indirect injection diesel it still has air in the fuel lines and
it must be bled out.

If you have metric tools it is easy to do if the indirect injection fuel pump
is on the right side of the motor and near the front of the upper cylinder block.

The steel fuel line at the very front on the injection pump has a banjo bolt on it
with a drain port and you need to loosen it to allow the air in the fuel lines to
exit the injection pump.

You only have to loosen the banjo bolt 1/2 a turn or so to open the drain port and
manually pump fuel through it to bleed the air out of the fuel lines.
When that is done tighten the banjo bolt back up using a light touch as the copper
washer under the head of the banjo bolt is very thin and can be damaged and cause
a fuel leak.

============================================================

If your mule had an direct injection diesel it would have fired and stayed running after you
replaced the fuel filter.

Direct injection

 

[fruitcakesa]

My M7040 is one of the easiest diesel powered tractors to change filter & bleed the air that I've owned. By chance is fuel shut off at water separator housing? Have you checked for good fuel flow from tank? I once owned a M4900 that had fuel problems. Local Kubota service manager advised me to check for clogged screen in fuel shut-off valve. Sure enough tiny white screen was clogged. I cleaned screen & solved fuel problem

The screen in the fuel strainer is clear

 

[CobyRupert]

Don’t know about that system, but with others, and brake systems, where pump is remote from bleeder, it’s handy to have two people so you can close bleeder when fuel is actively squirting out instead of closing it at a pump pause.

 

[LouNY]

Have you opened the bleeders on your fuel system?
Does it have one on the filter, if so open it and use your hand pump till bubble free fuel is coming out,
then close it. Move on in your system to the injection pump crack open the bleeder and again pump till
free of air.
Then you may have to crack loose the fitting on the lines to the injector and crank the tractor over till they start spitting fuel,
about that time she should be starting to spit and sputter and as they are tightened she should run.
Unless your shutoff solenoid has failed.

 

[CobyRupert]

I understand bleeding injectors, I’ve never had to do this, as I was always able to bled between filter and pump (at pump) and go.

When you bleed at injectors, is the purpose to eliminate air downstream of the pump? Or are you eliminating air upstream of the pump?
I never thought about it, but why wouldn’t air trapped “downstream” of the pump to the injectors not just get displaced through injectors by fuel being pumped behind it?

 

[fruitcakesa]

Don’t know about that system, but with others, and brake systems, where pump is remote from bleeder, it’s handy to have two people so you can close bleeder when fuel is actively squirting out instead of closing it at a pump pause.

There does not appear to be a bleeder. The procedure is: pump the fuel pump until resistance is felt, then crank engine.
I have done all that.

 

[LouNY]

When the injection pump is pumping small amounts of fuel and the injector lines have a lot of air in them the air will compress and not pop the injectors open to escape the system.