M6040 fuel flow path

[fruitcakesa]

I posted this new thread as I am still trying to track down my no-start issue and wanted to confirm the fuel flow path
From what I can trace, it follows this route:
1 - Fuel tank to water separator
2 - Water separator to lift pump
3 - Lift pump to fuel filter
4 - Fuel filter to IP.
Can someone confirm or order this correctly?
Thanks for all the suggestions in my other thread; the weather is supposed to moderate starting tomorrow so I can begin the troubleshooting on the M.

 

[kubotafreak]

Ive been following your issue. Have you checked the fuel shut off solenoid?

 

[JerryMT]

I posted this new thread as I am still trying to track down my no-start issue and wanted to confirm the fuel flow path
From what I can trace, it follows this route:
1 - Fuel tank to water separator
2 - Water separator to lift pump
3 - Lift pump to fuel filter
4 - Fuel filter to IP.
Can someone confirm or order this correctly?
Thanks for all the suggestions in my other thread; the weather is supposed to moderate starting tomorrow so I can begin the troubleshooting on the M.

I'm not familiar with all the fuel deliver systems that Kubota has but that's the general order of diesel engine fuel delivery systems.

 

[BruceP]

To be complete, this list should include the RETURN from the injectors back... (in some cased the IP also has a 'return' which is really bleed-by from the pistons)

 

[fruitcakesa]

To be complete, this list should include the RETURN from the injectors back... (in some cased the IP also has a 'return' which is really bleed-by from the pistons)

So, I should pull the supply line to the IP first and switch on to see if fuel flows?

 

[BruceP]

So, I should pull the supply line to the IP first and switch on to see if fuel flows?

I see you are a fellow Vermontisian

Are we still discussing the issue where your engine loses power on inclines?

This sure sounds like fuel-delivery problem to me. A pinhole leak between tank and lift-pump might suck air when having to 'pull' fuel up out of the tank.

One way to help isolate the problem is to feed fuel from temporary external tank (perhaps bungy-corded to the hood ABOVE the IP) so it is gravity-fed to inlet to lift-pump)

 

[fruitcakesa]

I see you are a fellow Vermontisian

Are we still discussing the issue where your engine loses power on inclines?

This sure sounds like fuel-delivery problem to me. A pinhole leak between tank and lift-pump might suck air when having to 'pull' fuel up out of the tank.

One way to help isolate the problem is to feed fuel from temporary external tank (perhaps bungy-corded to the hood ABOVE the IP) so it is gravity-fed to inlet to lift-pump)

I am indeed and yes that thread. But to answer my q, should I get fuel pumped from the ip supply when switched on?

 

[ruger1980]

I am indeed and yes that thread. But to answer my q, should I get fuel pumped from the ip supply when switched on?

I do not believe so. It looks like that model has a mechanical fuel pump. If you prime the fuel system with the hand primer you should get fuel at the injection pump inlet.

Does the engine lose power when the fuel tank is full?

 

[fruitcakesa]

I do not believe so. It looks like that model has a mechanical fuel pump. If you prime the fuel system with the hand primer you should get fuel at the injection pump inlet.

Does the engine lose power when the fuel tank is full?

Thanks for that, tank has not been full since the power loss issue began

 

[JerryMT]

So, I should pull the supply line to the IP first and switch on to see if fuel flows?

That how I would do it. If you get a gush of fuel, then the problem is not likely to be in that part of the fuel delivery system. If you have a lift pump then you'll want to activate it by turning on the key and attempting to crank the engine. If you don't get a gush of fuel, then you have to start moving toward the tank and repeating the test until you find the offending part. Does you lift pump have a "dome like" metal part with a screw in it? If it does, take it off and look for a screen under the dome.

 

[fruitcakesa]

That how I would do it. If you get a gush of fuel, then the problem is not likely to be in that part of the fuel delivery system. If you have a lift pump then you'll want to activate it by turning on the key and attempting to crank the engine. If you don't get a gush of fuel, then you have to start moving toward the tank and repeating the test until you find the offending part. Does you lift pump have a "dome like" metal part with a screw in it? If it does, take it off and look for a screen under the dome.

I'll have to look at it to confirm.

 

[BruceP]

Again...since your problem is engine cutting out when on an incline.... I suspect you will not find any issues with the tractor sitting level. Doing diagnostics with tractor on the level may not be worth the time.

My suggestion above using a remote fuel tank and actually DRIVE the tractor up an incline would give you some answers.

As ruger1980 suggests, FILLING the fuel tank and climbing up an incline may reveal some interesting results. (but may be far more expensive test than a 1-gallon tank strapped above the IP)

 

[fruitcakesa]

I tried the bottle feed to the IP and it popped a few times but it has been so cold that the battery ran low before it could catch.
However, while I was cranking it, a dribble of fuel began to flow the now open port on the fuel filter.
I put the battery on charge and plugged in the block heater and will try again in a couple of hours.
Maybe there is still a bunch of air between the FF and the IP?

 

[BruceP]

I tried the bottle feed to the IP and it popped a few times but it has been so cold that the battery ran low before it could catch.

I hear ya. Today it hit 29F...the warmest day in over two weeks.
Not the best weather to be working on equipment outside.

I would expect the lift-pump to be moving fuel... hence the dribble out of the open outlet of the filter.

Perhaps you can re-plumb the remote-tank to feed the inlet of the lift-pump. In this way, the fuel is still getting filtered before entering the IP. (we dont want any debris entering the IP nor injectors)

I say this because, based on your declared problem of stalling on an incline... I suspect there is a slight leak between tank and lift-pump. (which sucks air due to possible vacuum on an incline)

If there were a leak between lift-pump and IP... it would simply leak fuel. That section of fuel-line is always slightly pressurized and NEVER has a vacuum.

 

[North Idaho Wolfman]

Yes you have the path of fuel right.
Mechanical lift pump, so only pumps when cranking, (Everything you say is pointing to this being your failure point.)
If you didn't shut the fuel off at the strainer and your only getting minor fuel out of the filter outlet port, then that is pointing to the lift pump being bad, it should pulse fuel at a pretty good pace.

If you fill the tank then you won't have an issue because the lift pump becomes unneeded as gravity does the work, but when the lank level gets too low then it cant get fuel to the injection pump.

Really quick way to find out if this is your issue, fill the tank up!
If you can blead it and have it run normally, you have a bad lift pump!

 

[fruitcakesa]

Yes you have the path of fuel right.
Mechanical lift pump, so only pumps when cranking, (Everything you say is pointing to this being your failure point.)
If you didn't shut the fuel off at the strainer and your only getting minor fuel out of the filter outlet port, then that is pointing to the lift pump being bad, it should pulse fuel at a pretty good pace.

If you fill the tank then you won't have an issue because the lift pump becomes unneeded as gravity does the work, but when the lank level gets too low then it cant get fuel to the injection pump.

Really quick way to find out if this is your issue, fill the tank up!
If you can blead it and have it run normally, you have a bad lift pump!

Thanks Wolfman, the weather is supposed to warm over the next couple of days so I will be at it again tomorrow.

 

[fruitcakesa]

Since it is a balmy 20*F day, I headed out to the tractor to work.
First off, I disconnected the line from the FF to the fuel tank and blew compressed air into the tank.
I heard it bubbling so guessed it was cleared if it had been blocked.
Attempted to start after pumping the primer many times. Still no start.
Then I pulled the line from the FF to the IP at the FF and cranked it and fuel flowed freely from the open port... OK we got fuel at the filter.
I then pump the primer 60 more times and tried a crank and it fired a few times...yesss!
More priming, cranking, popping. After about 4 rounds of this it fired and continued to run...yay
So, perhaps it was something in the tank blocking the outlet.
I guess at some point, if this is the case, it will eventually plug again since it would still be in the tank.
A little compressed air now and then I can manage. Dropping the tank to clean it is not a winter job for me.
I went out and box bladed the drive uphill at full throttle and it did not miss a beat.
Thanks to all for the great advice.

 

[North Idaho Wolfman]

Excellent to hear!

 

[JerryMT]

I hear ya. Today it hit 29F...the warmest day in over two weeks.
Not the best weather to be working on equipment outside.

I would expect the lift-pump to be moving fuel... hence the dribble out of the open outlet of the filter.

Perhaps you can re-plumb the remote-tank to feed the inlet of the lift-pump. In this way, the fuel is still getting filtered before entering the IP. (we dont want any debris entering the IP nor injectors)

I say this because, based on your declared problem of stalling on an incline... I suspect there is a slight leak between tank and lift-pump. (which sucks air due to possible vacuum on an incline)

If there were a leak between lift-pump and IP... it would simply leak fuel. That section of fuel-line is always slightly pressurized and NEVER has a vacuum.

If there is an upstream restriction I would expect there to be little fuel for the lift pump to move. I wouldn't declare the lift pump as the culprit just yet. If there is full fuel flow upstream of the lift pump then I would agree.