Kubota B7500 wont start

CornGold3

New member

Equipment
Kubota B7500
May 27, 2021
17
0
1
Arkansas
I recently inherited a B7500 that will turn over but will not start. Where do I start to figure out what's wrong with it?
 

Henro

Well-known member

Equipment
B2910, BX2200, KX41-2V mini Ex.
May 24, 2019
1,566
437
83
North of Pittsburgh PA
I recently inherited a B7500 that will turn over but will not start. Where do I start to figure out what's wrong with it?
Start by making sure there is fuel in the tank.

Then separate the fuel line and see if fuel runs out of the line.

Change your fuel filter at some point.

Check you air filter to make sure it is clean and there is no blockage.

Report back with your results and someone with more experience and knowledge will be able to offer more advice...
 

CornGold3

New member

Equipment
Kubota B7500
May 27, 2021
17
0
1
Arkansas
Thanks Henro,

I removed the engine mounted fuel filter which had quite a bit of water in it, so I drain the diesel fuel out until all the water was removed from the tank. I removed the air filter and it looks really good. I put more fresh fuel in the tank. I tried turning it over but still the same thing, it's just spinning over but will not catch up. I sprayed starter fluid in the breather, it labor knocked a little but still would not start. I got in touch with the guy I bought the tractor from and he stated that he started the tractor one day, it was idling and suddenly it died and has not start again. He stated also that he took it in to a Kubota shop and they recommended an overhaul. I was just wondering is there a cheaper or alternate route?
 

Fedup

Member
Apr 6, 2016
77
1
8
Winchester
Just to be clear, you bought the tractor in this condition. The person you bought it from told you at that time about the running one day, died wouldn't start back, the overhaul recommendation, etc, and you bought it anyway? Or you bought it thinking you got a good running tractor at a good deal?
 

mendonsy

Member

Equipment
B7500HST/LA302
May 28, 2012
316
5
18
Mendon, NY
The B7500 has a small lift pump to draw fuel from the filter up to the injector pump. My B7500 developed a very small split in the hose between the filter and lift pump which cause it to draw air instead of fuel. The split was very hard to see and I only discovered the problem by accident.
The point of all this is that you should check everything between the filter and injectors for leaks.
 
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RCW

Well-known member
Lifetime Member

Equipment
BX2360, FEL, MMM, BX2750D snowblower. 1953 Minneapolis Moline ZAU
Apr 28, 2013
5,271
627
113
Chenango County, NY
Stop using Starter Fluid.

It can cause a bent rod.
 
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Henro

Well-known member

Equipment
B2910, BX2200, KX41-2V mini Ex.
May 24, 2019
1,566
437
83
North of Pittsburgh PA
Stop using Starter Fluid.

It can cause a bent rod.
PAY ATTENTION to RCW's advice!

Then consider if you could have a problem with the circuit/devices that shut the tractor down when the key is turned off.

I don't know your tractor. Get a workshop manual, which could be available at kubotabooks.com for free. You will have to look there and see if available.

Each tractor is different. Yours could have a setup like my BX2200, where you need a coil to be energized for the tractor to run. Actually, in my case, with the BX, there are two coils involved, but that is an aside.

It is possible that you have a fuel shut off solenoid coil that failed, which must be working to allow the tractor to run. This is just speculation, since I do not know your tractor.

DO NOT use starter fluid! If you do you may damage the engine more than you can imagine...
 
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JerryMT

Member

Equipment
Kubota M4500, NH TD95D,Ford 4610
Jun 17, 2017
234
7
18
The Palouse - North Idaho
Thanks Henro,

I removed the engine mounted fuel filter which had quite a bit of water in it, so I drain the diesel fuel out until all the water was removed from the tank. I removed the air filter and it looks really good. I put more fresh fuel in the tank. I tried turning it over but still the same thing, it's just spinning over but will not catch up. I sprayed starter fluid in the breather, it labor knocked a little but still would not start. I got in touch with the guy I bought the tractor from and he stated that he started the tractor one day, it was idling and suddenly it died and has not start again. He stated also that he took it in to a Kubota shop and they recommended an overhaul. I was just wondering is there a cheaper or alternate route?
It sounds like you drained a lot of water out of the tank and I would suspect this is where your problem lies. Bacteria can live in the fuel/water interface and live on the fuel causing snotty looking deposits that can clog tank outlets, fuel lines, fuel filter head and fuel filter itself. Draining the water helps but you have to get the rest of the crud out. This may require removing the tank but I would not do this unless you have to.

Remove the line from the tank to the filter, holding something under it to catch any fuel. The fuel should gush out like a cow peeing on a flat rock. If it doesn't you have found an obstruction between the tank and the filter. Remove the line from the tank and clear it and then using a small wire clean out any debris from the tank outlet. Next remove the filter from the housing and using compressed air, blow through the tank line attachment and see if the passages in the filter head are clear. If they are not they will need to be cleaned out. If they flow well then replace the filter with a new one and reconnect the line to the filter. Open the line between the injector pump (IP) and the filter on the pump end. Blow through this with compressed air. Again you are looking for high flow. Next assemble the entire fuel delivery system ( tank to filter , filter assembly, filter to IP). Kubota's often have a small lift pump in the circuit before the IP so make sure that is working by cranking the engine and feeling the IP end for pressure pulses and or fuel delivery.
Next bleed the fuel system per the owners manual. At this point you should have fuel to the IP. Reconnect the line to the IP and assure that you have bled the system properly. The engine should start if the IP is working and the engine has adequate compression. Make sure the battery is fully charged before you try to start.
 
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CornGold3

New member

Equipment
Kubota B7500
May 27, 2021
17
0
1
Arkansas
Start by making sure there is fuel in the tank.

Then separate the fuel line and see if fuel runs out of the line.

Change your fuel filter at some point.

Check you air filter to make sure it is clean and there is no blockage.

Report back with your results and someone with more experience and knowledge will be able to offer more advice...
Thank you for your response,

I made sure there was fuel in the tank, I didn't change the filter but I did remove the filter and the bowl and drained out the
PAY ATTENTION to RCW's advice!

Then consider if you could have a problem with the circuit/devices that shut the tractor down when the key is turned off.

I don't know your tractor. Get a workshop manual, which could be available at kubotabooks.com for free. You will have to look there and see if available.

Each tractor is different. Yours could have a setup like my BX2200, where you need a coil to be energized for the tractor to run. Actually, in my case, with the BX, there are two coils involved, but that is an aside.

It is possible that you have a fuel shut off solenoid coil that failed, which must be working to allow the tractor to run. This is just speculation, since I do not know your tractor.

DO NOT use starter fluid! If you do you may damage the engine more than you can imagine...
Ok, I got it, No More Starting Fluid!
I'm going to go online and see if I can order the workshop manual for the B7500.
Thank you!
 

CornGold3

New member

Equipment
Kubota B7500
May 27, 2021
17
0
1
Arkansas
You did push the stop knob in I assume???
It sounds like you drained a lot of water out of the tank and I would suspect this is where your problem lies. Bacteria can live in the fuel/water interface and live on the fuel causing snotty looking deposits that can clog tank outlets, fuel lines, fuel filter head and fuel filter itself. Draining the water helps but you have to get the rest of the crud out. This may require removing the tank but I would not do this unless you have to.

Remove the line from the tank to the filter, holding something under it to catch any fuel. The fuel should gush out like a cow peeing on a flat rock. If it doesn't you have found an obstruction between the tank and the filter. Remove the line from the tank and clear it and then using a small wire clean out any debris from the tank outlet. Next remove the filter from the housing and using compressed air, blow through the tank line attachment and see if the passages in the filter head are clear. If they are not they will need to be cleaned out. If they flow well then replace the filter with a new one and reconnect the line to the filter. Open the line between the injector pump (IP) and the filter on the pump end. Blow through this with compressed air. Again you are looking for high flow. Next assemble the entire fuel delivery system ( tank to filter , filter assembly, filter to IP). Kubota's often have a small lift pump in the circuit before the IP so make sure that is working by cranking the engine and feeling the IP end for pressure pulses and or fuel delivery.
Next bleed the fuel system per the owners manual. At this point you should have fuel to the IP. Reconnect the line to the IP and assure that you have bled the system properly. The engine should start if the IP is working and the engine has adequate compression. Make sure the battery is fully charged before you try to start.
Hello JerryMT, I apologize for the delay, the Memorial Day Holiday along with other gatherings took up most of my time during the weekend. I will start on your suggestions this evening after work and will report back what I did and the result I achieved. Thanks for your help.
 

CornGold3

New member

Equipment
Kubota B7500
May 27, 2021
17
0
1
Arkansas
It sounds like you drained a lot of water out of the tank and I would suspect this is where your problem lies. Bacteria can live in the fuel/water interface and live on the fuel causing snotty looking deposits that can clog tank outlets, fuel lines, fuel filter head and fuel filter itself. Draining the water helps but you have to get the rest of the crud out. This may require removing the tank but I would not do this unless you have to.

Remove the line from the tank to the filter, holding something under it to catch any fuel. The fuel should gush out like a cow peeing on a flat rock. If it doesn't you have found an obstruction between the tank and the filter. Remove the line from the tank and clear it and then using a small wire clean out any debris from the tank outlet. Next remove the filter from the housing and using compressed air, blow through the tank line attachment and see if the passages in the filter head are clear. If they are not they will need to be cleaned out. If they flow well then replace the filter with a new one and reconnect the line to the filter. Open the line between the injector pump (IP) and the filter on the pump end. Blow through this with compressed air. Again you are looking for high flow. Next assemble the entire fuel delivery system ( tank to filter , filter assembly, filter to IP). Kubota's often have a small lift pump in the circuit before the IP so make sure that is working by cranking the engine and feeling the IP end for pressure pulses and or fuel delivery.
Next bleed the fuel system per the owners manual. At this point you should have fuel to the IP. Reconnect the line to the IP and assure that you have bled the system properly. The engine should start if the IP is working and the engine has adequate compression. Make sure the battery is fully charged before you try to start.
Hello JerryMT,

How can I determine which shop manual to download?
How do I know which engine I have?

Please advise, thanks!
 

JerryMT

Member

Equipment
Kubota M4500, NH TD95D,Ford 4610
Jun 17, 2017
234
7
18
The Palouse - North Idaho
Hello JerryMT,

How can I determine which shop manual to download?
How do I know which engine I have?

Please advise, thanks!
There should be a data plate on your tractor specifying the engine model number. There is on my old M4500. It should also specify the tractor model number and the serial number. You get the WSM that goes the model number.That's how it worked for me.

I'll warn you that the Kubota WSM's leave a lot to be desired, especially the older ones. They are among the most poorly written manuals I have ever seen.
Maybe the moderator, North Idaho Wolfman could give you some more info on these issues.
 

CornGold3

New member

Equipment
Kubota B7500
May 27, 2021
17
0
1
Arkansas
The B7500 has a small lift pump to draw fuel from the filter up to the injector pump. My B7500 developed a very small split in the hose between the filter and lift pump which cause it to draw air instead of fuel. The split was very hard to see and I only discovered the problem by accident.
The point of all this is that you should check everything between the filter and injectors for leaks.
There should be a data plate on your tractor specifying the engine model number. There is on my old M4500. It should also specify the tractor model number and the serial number. You get the WSM that goes the model number.That's how it worked for me.

I'll warn you that the Kubota WSM's leave a lot to be desired, especially the older ones. They are among the most poorly written manuals I have ever seen.
Maybe the moderator, North Idaho Wolfman could give you some more info on these issues.
Thanks JerryMT, I saw the tag at the bottom of the engine, located on the engine frame. I just can't decipher what the number means.
Will the number tell me the year model of this tractor as well?
 

CornGold3

New member

Equipment
Kubota B7500
May 27, 2021
17
0
1
Arkansas
Hello JerryMT, I apologize for the delay, the Memorial Day Holiday along with other gatherings took up most of my time during the weekend. I will start on your suggestions this evening after work and will report back what I did and the result I achieved. Thanks for your help.
JerryMT, I can I perform a compression check to ensure that I have adequate cylinder compression? I new so just as you've explained the other procedures please do the same for the cylinder compression check!
Thanks,
 

JerryMT

Member

Equipment
Kubota M4500, NH TD95D,Ford 4610
Jun 17, 2017
234
7
18
The Palouse - North Idaho
JerryMT, I can I perform a compression check to ensure that I have adequate cylinder compression? I new so just as you've explained the other procedures please do the same for the cylinder compression check!
Thanks,
Get yourself a diesel compression test kit with the adapter that fits the glow plug hole. Make sure the battery is fully charged.

Remove the glow plugs wires and then the glow plug. Remove them all to make it easy on the starter. Install the compression tester adapter in the first glow plug hole. Attach the hose with the compression gauge to the adapter. Crank the starter until the pressure does not increase any further and record the "dry" compression pressure reading. (Do not engage the starter for more than 30 seconds). Remove the gauge and put a couple of table spoons of engine oil in the glow plug hole, reconnect the gauge and repeat the test, recording the "wet " compression pressure. Do that on each cylinder and come back here with the numbers.

In general, your pressures should not be lower that 350-375 psi. Higher is better. They should not vary greatly ~+/- 10%. ( The WSM for your model will give you better numbers as these are based on my general experience.) If you see that that the wet pressures are significantly higher than the dry pressure this would indicate worn rings. If you have a cylinder that is low and does not improve with adding oil that indicates a leaking valve and it could be burned or out of adjustment.
 
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