M9000 Fuel Issue?

dvcochran · Oct 18, 2019

I have had my M9000 for 3 years and it has been a strong running, reliable tractor. After our first hay cutting this spring, which takes about 30-40 hours per tractor my M9 started loosing power after running for a short amount of time (15-20 minutes). It never stalled but would smother down like it was going to stall. I could clutch it for several seconds and it would pick back up and it would be ok for few minutes.
I thought I had bad fuel so I drained the tanks, checked the crossover line between tanks, blew out all the lines and vents, and replaced the fuel and water separator filters. Got fuel from another source and it ran fine through second cutting, third cutting and about 30 house of bush hogging.
Earlier this week I did about 20 hours of bush hogging and yesterday the tractor started doing the same thing it did earlier this year, smothering down and nearly stalling. I blew out the vents today, added 10 gallons of fuel from another source, added about 10 gallons worth of Power Service Cetane Boost and 10 gallons of PS fuel and tank cleaner and tried it again. After about 15-20 minutes of mowing it started doing the same thing only worse and stalled a couple of times.
I am not certain if this tracks, but the problem started yesterday after bouncing around on some rough, hilly ground.
I assume I need to drain the tanks and change the filters again? Is there anything else I should check?
I saw a few posts about the water separator and a screen. It is easier to remove mine from the tractor (1 bolt) when servicing so I had it off earlier this year and do not remember seeing a screen.

Any suggestions are appreciated.

Bulldog · Oct 18, 2019

If the filters don't fix it I'd probably look at the fuel line that comes from the tank to the primary filter. I've seen trash get right there and cause problems.

Roadworthy · Oct 18, 2019

It is possible you have an algae build up near or at the fuel tank exit. If you can remove the tank fitting you can easily check that. You could then use an algicide additive to control it.

Tx Jim · Oct 19, 2019

Several yrs back I owned a M4900 that acted similar to your tractor. I checked tank vents & blew out fuel lines but didn't solve the engine stalling problem. I talked to local Kubota dealer service manager. He told me to check for clogged screen in water separater fuel cut valve. I removed retaining screw & pulled valve out of housing. Tiny screen was clogged. Cleaned screen reinstated valve & engine stalling problem was solved.

dvcochran · Oct 19, 2019

Tx Jim said:
Several yrs back I owned a M4900 that acted similar to your tractor. I checked tank vents & blew out fuel lines but didn't solve the engine stalling problem. I talked to local Kubota dealer service manager. He told me to check for clogged screen in water separater fuel cut valve. I removed retaining screw & pulled valve out of housing. Tiny screen was clogged. Cleaned screen reinstated valve & engine stalling problem was solved.

Are you talking about the small shut-off lever on the water separator? You removed the screw and removed the handle/shaft and there is a screen there?
I have the separator pulled up on the KubotaUSA website but cannot figure out how to insert it here as a picture. Kubota will not let me hyper-link to the diagram page.

I you want to look it up search M9000 cab and go to fuel system. Parts #90, 100, 110, 120 and are you talking about "B"? I have not found a description for it yet.
Are we on the same page?

SidecarFlip · Oct 19, 2019

Bulldog said:
If the filters don't fix it I'd probably look at the fuel line that comes from the tank to the primary filter. I've seen trash get right there and cause problems.

Bingo.....

SidecarFlip · Oct 19, 2019

Bulldog said:
If the filters don't fix it I'd probably look at the fuel line that comes from the tank to the primary filter. I've seen trash get right there and cause problems.

That or the saddle tank vent line. The lift pump cannot pull enough head to overcome the fuel starvation issue from a clogged vent line or clogged feed line. Remember, the fuel is 'pulled' from the saddle tanks through the primary spin on fuel filter and the washable secondary filter / water separator via the lift pump, not 'pushed'.

dvcochran · Oct 19, 2019

SidecarFlip said:
That or the saddle tank vent line. The lift pump cannot pull enough head to overcome the fuel starvation issue from a clogged vent line or clogged feed line. Remember, the fuel is 'pulled' from the saddle tanks through the primary spin on fuel filter and the washable secondary filter / water separator via the lift pump, not 'pushed'.

I was able to spend some time working on the tractor today. I pulled the separator and inspected/cleaned it. There was a small wad of trash/grass in the bowl which is of course concerning. I replaced the main fuel filter and blew out the line down to the tank. I would hear bubbling in the tank so hopefully that is a good thing. I removed the lift pump and tested it in a bucket of fuel. It felt strong and made a good stream once it got primed.
I had to go to work before I got a prime back to the lift pump. I am going to double check all the vent lines and try again to get a prime. Have you ever tried using a hand operated bleeder pump instead of cranking the starter so much? Any suggestions on the best way to pull prime from the tank up?
I was looking at the online diagrams; it does not show it but is there a pipe or something inside the tank to suction from close to the bottom of the tank? I wondered if something could be going on there.
What you mentioned about the vent lines makes sense. I had also thought about putting some small engine tank filters on the ends (like in a weedeater tank) of the vent lines to keep the dirt dobbers out. Does that sound like a good idea?
Lastly, I saw that there are check valves in a couple of places in the fuel lines. If they were bad the tractor would loose prime and be hard to start wouldn't it?

Tx Jim · Oct 20, 2019

dvcochran said:
I you want to look it up search M9000 cab and go to fuel system. Parts #90, 100, 110, 120 and are you talking about "B"? I have not found a description for it yet.
Are we on the same page?

If I'm understanding Kubota parts correctly "B" is included in complete seperator(key 010). Water sperator parts schematic for M4900 & M9000 are the same. Screen I cleaned resembled (B). Normally faulty fuel check valves cause difficult starting due to fuel draining back to tank from filter.

SidecarFlip · Oct 20, 2019

dvcochran said:
I was able to spend some time working on the tractor today. I pulled the separator and inspected/cleaned it. There was a small wad of trash/grass in the bowl which is of course concerning. I replaced the main fuel filter and blew out the line down to the tank. I would hear bubbling in the tank so hopefully that is a good thing. I removed the lift pump and tested it in a bucket of fuel. It felt strong and made a good stream once it got primed.
I had to go to work before I got a prime back to the lift pump. I am going to double check all the vent lines and try again to get a prime. Have you ever tried using a hand operated bleeder pump instead of cranking the starter so much? Any suggestions on the best way to pull prime from the tank up?
I was looking at the online diagrams; it does not show it but is there a pipe or something inside the tank to suction from close to the bottom of the tank? I wondered if something could be going on there.
What you mentioned about the vent lines makes sense. I had also thought about putting some small engine tank filters on the ends (like in a weedeater tank) of the vent lines to keep the dirt dobbers out. Does that sound like a good idea?
Lastly, I saw that there are check valves in a couple of places in the fuel lines. If they were bad the tractor would loose prime and be hard to start wouldn't it?

On the top of the spin on fuel filter (at least on both my M9's), there is a flat 'knob' if you want to call it that', that primes the filter and the seperator as well as the lift pump and the injection pump. Operates just like the pump on a Caterpillar diesel engine. You 'pump' it until it becomes hard to pump (at the same time the small handwheel on the top of the injection pump must be open to allow entrained air to escape. Pump it until it gets firm, start the motor and allow it to idle with the little handwheel open (on top of the pump) to let any residual air out, do that for a couple minutes and close it. That should eliminate any air in the system.

How it works on my M's. I'm sure the newer common rail motors are different.

A pickup screen on the tank might not be a bad addition. Something I might do myself. as my pickup / fuel sending unit and return lines are all easily accessable on the right saddle tank under the cab floor. My OS 9, not so much.

whitetiger · Oct 20, 2019

SidecarFlip said:
That or the saddle tank vent line. The lift pump cannot pull enough head to overcome the fuel starvation issue from a clogged vent line or clogged feed line. Remember, the fuel is 'pulled' from the saddle tanks through the primary spin on fuel filter and the washable secondary filter / water separator via the lift pump, not 'pushed'.

The lift pump sucks fuel from the tank through the water separator and pressures it through the spin-on filter to the injection pump.

The hand primer pump sucks fuel from the tank through the separator and lift pump and pressures it through the spin-on filter to the injection pump.

SidecarFlip · Oct 20, 2019

Whatever you say boss.

Fuel from the fuel tank (1) suck up by feed pump (9) through the separator (2) and then enter the fuel filter (3). After impurities such as dirt, water etc. are removed, the fuel enter the injection pump (4) and is pressurized. The fuel pressurized by the injection pump to the opening pressure (13.7 to 14.71 MPa, 140 to 150 kgf/cm2, 1991 to 2062 psi) of the injection nozzle (5) is injected into the combustion chamber. Part of the fuel fed to the injection nozzle (5) lubricates the moving parts of the plunger inside the nozzle, then returns to the fuel tank (1) through the overflow pipe (7) and check valve (8) another end of overflow pipe is connected to pump body by joint. Thus, this system is designed to prevent mixing of air into fuel which causes hard starting. [1] FUEL FILTER The fuel filter is installed between the fuel tank and fuel lift pump, and serves to remove dirt and impurities from the fuel. Fuel from the fuel tank enters the outside of the filter element (2) and passes through the filter element under its own pressure. As it passes through, the dirt and impurities in the fuel are filtered out, allowing only clean fuel to enter the interior of the filter element. The feed pump (1) sends fuel from the fuel tank to the injection pump by applying pressure to fuel.

whitetiger · Oct 20, 2019

SidecarFlip said:
Whatever you say boss.

Fuel from the fuel tank (1) suck up by feed pump (9) through the separator (2) and then enter the fuel filter (3). After impurities such as dirt, water etc. are removed, the fuel enter the injection pump (4) and is pressurized. The fuel pressurized by the injection pump to the opening pressure (13.7 to 14.71 MPa, 140 to 150 kgf/cm2, 1991 to 2062 psi) of the injection nozzle (5) is injected into the combustion chamber. Part of the fuel fed to the injection nozzle (5) lubricates the moving parts of the plunger inside the nozzle, then returns to the fuel tank (1) through the overflow pipe (7) and check valve (8) another end of overflow pipe is connected to pump body by joint. Thus, this system is designed to prevent mixing of air into fuel which causes hard starting. [1] FUEL FILTER The fuel filter is installed between the fuel tank and fuel lift pump, and serves to remove dirt and impurities from the fuel. Fuel from the fuel tank enters the outside of the filter element (2) and passes through the filter element under its own pressure. As it passes through, the dirt and impurities in the fuel are filtered out, allowing only clean fuel to enter the interior of the filter element. The feed pump (1) sends fuel from the fuel tank to the injection pump by applying pressure to fuel.

You might want to go look again, the lift pump is between the water separator and the fuel filter on all M series tractors. Even yours.

SidecarFlip · Oct 21, 2019

whitetiger said:
You might want to go look again, the lift pump is between the water separator and the fuel filter on all M series tractors. Even yours.

Right out of the shop manual (copy and paste), have it in hard copy and PDF.

Irregardless, there is, most likely, a flow issue between the in tank fuel pickup and the injection pump or clogged filter. Could also be a failing component but I don't think so. Could also be a blocked fuel tank vent hose in as much as they do not vent via the fuel cap which is why I stated ( think I did) to remove the fuel cal and stuff a shop towel in the filler opening and run the tractor. The towel will allow the tank to vent without allowing foreign material to enter the tanks. M's only draw off the right tank, not both. The under frame crossover equalizes the fuel level in both tanks.

Process of elimination.

dvcochran · Oct 21, 2019

SidecarFlip said:
On the top of the spin on fuel filter (at least on both my M9's), there is a flat 'knob' if you want to call it that', that primes the filter and the seperator as well as the lift pump and the injection pump. Operates just like the pump on a Caterpillar diesel engine. You 'pump' it until it becomes hard to pump (at the same time the small handwheel on the top of the injection pump must be open to allow entrained air to escape. Pump it until it gets firm, start the motor and allow it to idle with the little handwheel open (on top of the pump) to let any residual air out, do that for a couple minutes and close it. That should eliminate any air in the system.

How it works on my M's. I'm sure the newer common rail motors are different.

A pickup screen on the tank might not be a bad addition. Something I might do myself. as my pickup / fuel sending unit and return lines are all easily accessable on the right saddle tank under the cab floor. My OS 9, not so much.

Thank you, work has been taking all of my time and I cannot stay on the fuel issue long enough to figure it out. I have a POS John Deere 2640 that I can feed with so getting by. I guess I should not dog it too hard, it does at least start and run with a little effort.

On the top of the primary filter assembly there is a "button" or round knob. I tried pushing it vertically and it would not move. I tried turning it horizontally (spinning it) and inadvertently backed the screw holding it on complete off. A PITA to get back on with the hood and loader on the tractor.
To clarify, I should be able to push that knob DOWN and pump fuel? It felt very firm.
I do see the sending unit. There is a tube going up to the elbow on top of the tank?
The last thing I tried doing is to trace the line up to the primary filter. Again, had to do by yourself with the loader bracket in the way. I will have an extra set of eyes/hands tomorrow and can hopefully figure this out.
Regarding the vent piping and lines; do you ever do more than compressed air to clean them out? One time when the tractor was smothering out I took the fuel cap off wondering if I could hear a "whoosh" of air but did not.
I feed at two different location so I have to figure this out.
Thanks for any advise.

SidecarFlip · Oct 21, 2019

dvcochran said:
Thank you, work has been taking all of my time and I cannot stay on the fuel issue long enough to figure it out. I have a POS John Deere 2640 that I can feed with so getting by. I guess I should not dog it too hard, it does at least start and run with a little effort.

On the top of the primary filter assembly there is a "button" or round knob. I tried pushing it vertically and it would not move. I tried turning it horizontally (spinning it) and inadvertently backed the screw holding it on complete off. A PITA to get back on with the hood and loader on the tractor.
To clarify, I should be able to push that knob DOWN and pump fuel? It felt very firm.

Vertical movement only and I've done what you did and with the loader on, you need midget hands to get the knob screw back in...lol. I should move up and down, it's spring loaded so it comes up under spring pressure and when pushed down you can
'hear the fuel gurgle in the right saddle tank

I do see the sending unit. There is a tube going up to the elbow on top of the tank? Yes, along with the sending unit power wires that energize the float and energize the fuel gauge.

The last thing I tried doing is to trace the line up to the primary filter. Again, had to do by yourself with the loader bracket in the way. I will have an extra set of eyes/hands tomorrow and can hopefully figure this out. One thing about M9 with loaders installed is, it's real tight in there.

Regarding the vent piping and lines; do you ever do more than compressed air to clean them out? One time when the tractor was smothering out I took the fuel cap off wondering if I could hear a "whoosh" of air but did not.
I feed at two different location so I have to figure this out.
Thanks for any advise.

Candidly, I have never had a fuel starvation issue with either but I'd only use low pressure compressed air and there would be no 'whoosh' when removing the fuel cap because it would be negative pressure not positive and probably not all that much pressure differential.

dvcochran · Oct 21, 2019

SidecarFlip said:
Whatever you say boss.

Fuel from the fuel tank (1) suck up by feed pump (9) through the separator (2) and then enter the fuel filter (3). After impurities such as dirt, water etc. are removed, the fuel enter the injection pump (4) and is pressurized. The fuel pressurized by the injection pump to the opening pressure (13.7 to 14.71 MPa, 140 to 150 kgf/cm2, 1991 to 2062 psi) of the injection nozzle (5) is injected into the combustion chamber. Part of the fuel fed to the injection nozzle (5) lubricates the moving parts of the plunger inside the nozzle, then returns to the fuel tank (1) through the overflow pipe (7) and check valve (8) another end of overflow pipe is connected to pump body by joint. Thus, this system is designed to prevent mixing of air into fuel which causes hard starting. [1] FUEL FILTER The fuel filter is installed between the fuel tank and fuel lift pump, and serves to remove dirt and impurities from the fuel. Fuel from the fuel tank enters the outside of the filter element (2) and passes through the filter element under its own pressure. As it passes through, the dirt and impurities in the fuel are filtered out, allowing only clean fuel to enter the interior of the filter element. The feed pump (1) sends fuel from the fuel tank to the injection pump by applying pressure to fuel.

Any chance you can send me the WSM in pdf format so I can correspond the numbers in you post?

whitetiger · Oct 21, 2019

Depending on whether your M9000 is a cab or ROPS model dictates how the fuel tanks are vented. ROPS models run a vent hose from the LH tank to the RH tank, then from the RH tank to the fill tube and use a vented cap. The cab models use vent hoses in the hood support in front of the cab and a non vented cap. I assume you have a cab as you mentioned mud dobbers plugging the hoses. There is one for each tank and must be clear.

The fact that you stated you found grass debris in the water separator bowl pretty much says that the RH tank has debris in it and it is intermittently plugging the standpipe into the tank. The debris is most likely keeping enough fuel from being sucked out of the tank to supply your engine. The RH tank will need to be cleaned out. The standpipe, hose and water separator would also need to be blown out.

I run into this problem 5 or 6 times a year on M series as its not that uncommon.

SidecarFlip · Oct 22, 2019

dvcochran said:
Any chance you can send me the WSM in pdf format so I can correspond the numbers in you post?

PM me with your e-mail addy and I'll send you a PDF copy.

Jlambert · Aug 10, 2022

I agree the shop manual does say it goes through the spin on filter first, but it doesn't. I was scratching my head when I saw that because you want the water and big debris filtered out before the spin on filter.

M9000 Fuel Issue?

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