Kubota 9580

[Craig Noble]

Tractor keeps losing prime.
New lift pump installed, new rubber fuel lines installed, tank bypassed with external tank, water separator bypassed for testing purposes, all steel pressure fuel lines examined for cracks or loose connections, new fuel filter.
Tractor has been into Kubota for other work about 3 or 4 times and I have asked them to try and find the problem while they have it in the shop. So far no luck and the fuel issues persist.
I'm almost at the point of selling it and replacing it with an other old school tractor no newer than the early 1970's but not willing to take a $15000 loss of what I have into it.
If anybody out there has had to deal with this problem I would welcome your input.

Thanks in advance,
Craig

 

[dvcochran]

First and foremost make certain the tank vent hoses are not stopped up to dirt dobbers. This is a reoccurring theme and will cause your symptoms.

My M9000 had a similar problem. Not in exact order but:
Dropped the tanks, cleaned and inspected.
At first I blew out the existing lines taking them apart at each joint.
Cleaned water separator and replaced filter.
Replaced fuel filter.
I did better for a while but started the original problem; it would bog down and loose power.
I went back through the process of blowing out lines. On a whim I cut a chaffed end off the line between separator and filter and found about three inches of grass in the line. Somehow it was not blowing out using compressed air.
I replaced all the hoses And the clamps, cleaned the separator and replace the filter again and never had the problem again.

If you know for certain everything has been replaced (hoses/clamps, etc...) and the tanks are clean I think I would pull the pump and have it pressure tested. You probably know these system Pull the fuel into the pump.

 

[whitetiger]

I think I would pull the pump and have it pressure tested. You probably know these system Pull the fuel into the pump.

There is a mechanical fuel lift pump that pulls the fuel from the tank and through the water separator. It then pushes fuel through the spin-on filter and into the injection pump.
The failure is usually the mechanical lift pump or the filter head.

 

[dvcochran]

There is a mechanical fuel lift pump that pulls the fuel from the tank and through the water separator. It then pushes fuel through the spin-on filter and into the injection pump.
The failure is usually the mechanical lift pump or the filter head.

I stand corrected. Totally forgot about the little lift pump. The OP should be able to place it in a jar of fuel and test it out. At least that is how my local Kubota dealer/mechanic said they test them.

 

[whitetiger]

I stand corrected. Totally forgot about the little lift pump. The OP should be able to place it in a jar of fuel and test it out. At least that is how my local Kubota dealer/mechanic said they test them.

Put the lift pump in a jar of fuel to test it?????????????????????
Why not just pull off the outlet hose and crank the engine over. You get a quick, real-world, accurate, factual result. If it pumps fuel, it's OK, if it does not pump fuel and has fuel to it, it's failed.
You can also remove both hoses, put a hand vacuum pump on the outlet, block the inlet, pull 3-5 inches. See if it holds a vacuum. If it does, the diaphragm is good.

 

[dvcochran]

Put the lift pump in a jar of fuel to test it?????????????????????
Why not just pull off the outlet hose and crank the engine over. You get a quick, real-world, accurate, factual result. If it pumps fuel, it's OK, if it does not pump fuel and has fuel to it, it's failed.
You can also remove both hoses, put a hand vacuum pump on the outlet, block the inlet, pull 3-5 inches. See if it holds a vacuum. If it does, the diaphragm is good.

In a word, for isolation. Let's say there is an issue upstream of the pump and you test the way you mentioned and you 'feel' it check out. You replace the pump and still have the same intermittent issue. So all you have accomplished is the cost of time and materials. If you are the charging mechanic, this is the worst kind of troubleshooting, aka parts swapping. Costs that are unnecessarily passed on to the customer.
Removing the pump takes all of 2-3 minutes. It allows for a physical inspection of the pump and an operational test.
When I first had the same problem as the OP I sure wish I had isolated the components in order and tested them one at a time. It would have saved me a lot of time and grief.

@Craig Noble , did you figure out your problem? If you did hope you post how you figured it out to help others.

 

[whitetiger]

In a word, for isolation. Let's say there is an issue upstream of the pump and you test the way you mentioned and you 'feel' it check out. You replace the pump and still have the same intermittent issue. So all you have accomplished is the cost of time and materials. If you are the charging mechanic, this is the worst kind of troubleshooting, aka parts swapping. Costs that are unnecessarily passed on to the customer.
Removing the pump takes all of 2-3 minutes. It allows for a physical inspection of the pump and an operational test.
When I first had the same problem as the OP I sure wish I had isolated the components in order and tested them one at a time. It would have saved me a lot of time and grief.

@Craig Noble , did you figure out your problem? If you did hope you post how you figured it out to help others.

Sooooooooooooo, you think removing the lift pump and placing it in a jar of fuel is a foolproof method of testing it????????
I have worked as a dealership Tech for 40 years, had several hundred hours of manufactures sponsored training from 6 major tractor and diesel engine manufactures. Not one has taught to remove the lift pump, place it in a jar of fuel, and assess its fitness. That makes no logical sense at all.
Can you stick an injection pump in a jar of fuel and test it also? That would save a lot of time and money.

 

[dvcochran]

Sooooooooooooo, you think removing the lift pump and placing it in a jar of fuel is a foolproof method of testing it????????
I have worked as a dealership Tech for 40 years, had several hundred hours of manufactures sponsored training from 6 major tractor and diesel engine manufactures. Not one has taught to remove the lift pump, place it in a jar of fuel, and assess its fitness. That makes no logical sense at all.
Can you stick an injection pump in a jar of fuel and test it also? That would save a lot of time and money.

Welllllllllllllllllllllll, Yes. I have tested fuel pumps on numerous different equipment brands like this. It is a very, very common test.
Who said anything about the injection pump except you? That is a pretty stupid assertion from such an experienced mechanic, but I get the joke.
I laud your years of service and training. I never questioned your ability yet you chose to question mine. In many circles that is known as 'short man's syndrome'.

I feely admitted my omission of the pump in one of my posts and simply explained my troubleshooting process. I also explained that your test was inconclusive for my problem (as I had already tried it) and that I did not figure out my problem until I began isolating things piece by piece. Why you took my comments as a challenge I have zero clue.

You may be a great mechanic, I have no firsthand experience to confirm that. You may be a parts swapper, I have no firsthand experience to confirm that. But you certainly did get defensive when I mentioned this method of service now didn't you?
I have no beef with you but you need to check your ego. If you don't want to help people why are you on this site?

So, here is some added manufacturer training for you. Pop a hose with a low pressure gauge on the outlet side of the lift pump, manually operate it in a bowl of fuel and test for pressure. How hard is this to understand.
Sometimes close enough just, isn't. I get it. An experienced person learns the reward of skipping steps. AND an experienced person learns inherent risk of skipping steps. It does not appear you are there yet.

I don't feel the need to compare resume's but I no problem with it if you feel the need.

 

[whitetiger]

Welllllllllllllllllllllll, Yes. I have tested fuel pumps on numerous different equipment brands like this. It is a very, very common test.
Who said anything about the injection pump except you? That is a pretty stupid assertion from such an experienced mechanic, but I get the joke.
I laud your years of service and training. I never questioned your ability yet you chose to question mine. In many circles that is known as 'short man's syndrome'.
Maybe in your circle, but just for the record, I am 6'4". Hardly a candidate for your "Short man's Syndromne".

I feely admitted my omission of the pump in one of my posts and simply explained my troubleshooting process. I also explained that your test was inconclusive for my problem (as I had already tried it) and that I did not figure out my problem until I began isolating things piece by piece. Why you took my comments as a challenge I have zero clue.
You are telling people to remove their fuel pump, put it in a jar of fuel as the test to check if it works. You are not checking the actuator arm to see if it is slightly bent, you are not checking the cam lobe that strokes the pump, you are not checking to see if the diaphragm has a slight leak, etc.
Why go through all the steps of removing and half testing the pump when you can do it more thoroughly and quicker with it on the engine?
I guess that you did Baptize your pump though.

You may be a great mechanic, I have no firsthand experience to confirm that. You may be a parts swapper, I have no firsthand experience to confirm that. But you certainly did get defensive when I mentioned this method of service now didn't you?
When a post miss leads people, I point it out. If you are don't want to help people, why are you on this site?
I have no beef with you but you need to check your ego. If you don't want to help people why are you on this site?
Seems that an ego check is more suited to you.

So, here is some added manufacturer training for you. Pop a hose with a low pressure gauge on the outlet side of the lift pump, manually operate it in a bowl of fuel and test for pressure. How hard is this to understand.
You are only testing part of the fuel lift pumps operation as I listed a few paragraphs before. Just because the pump builds pressure in a jar or bowl of fuel does not fully test the fuel pump. The engine has a cam that strokes the pump in a certain range only, something you can not duplicate in your jar of fuel. The diaphragm may have a leak that you are not testing for either.
If you leave it on the engine, crank the engine to check its operation, you get an accurate and real-world test of the pump. By checking it with a handheld vacuum pump, you will verify the diaphragm has no leak. How hard is this to understand??
Go back and reread your very own post, #4.

Sometimes close enough just, isn't. I get it. An experienced person learns the reward of skipping steps. AND an experienced person learns inherent risk of skipping steps. It does not appear you are there yet.
That is nothing more than your own opinion, void of any facts.

I don't feel the need to compare resume's but I no problem with it if you feel the need.
LOL, I have absolutely no need to compare resumes, especially after this thread.

This forum is to share and help people, not mislead them.

 

[dvcochran]

Like I have already said but apparently need to tell you again, your method(s) would not diagnose my issue. Isolating things was the best way to find my problem; this is consistent with troubleshooting across planes.
Of course the rod and actuation of the pump is going to be tested in place, but only AFTER all other issues are resolved.

You are obviously oblivious but short man's syndrome has Nothing to do with stature. Think about it for a little while and I am certain you can figure this one out.

I am telling people my experience with a similar problem and what I did, and not do, that led to fixing the problem. All you have done is crow about your height (?), years of experience, and bash other peoples ideas that are different from you own. That is the worst kind of help.

 

[kubotafreak]

Craig,
What timeline are we talking loosing prime. 30 min, two days, two weeks? Usually they leak externally and can be spotted easy. Some try the white powder method to a cleaned engine to spot the wet areas.(I never tried this except the spray for weather-strip water leaks).
I think the leak if not external is from injectors leaking down, or the high pressure injection pump is. To test, I would remove the hard lines, place great care in not turning the delivery valves at the top of pump(double wrench to remove hard line here). With the injectors and delivery valves should hold fuel on top of them. If either a delivery valve head, or injector top has leaked down, I would suspect.
Does the machine smoke much on restart hot? Would be a hint some fuel has leaked down from an injector. If you seem to be gaining oil, your injection pump may be leaking into the crankcase.
Hope this gives another perspective since you seem to have chased the feed lines already.

 

[whitetiger]

Like I have already said but apparently need to tell you again, your method(s) would not diagnose my issue. Isolating things was the best way to find my problem; this is consistent with troubleshooting across planes.
Of course the rod and actuation of the pump is going to be tested in place, but only AFTER all other issues are resolved.

You are obviously oblivious but short man's syndrome has Nothing to do with stature. Think about it for a little while and I am certain you can figure this one out.

I am telling people my experience with a similar problem and what I did, and not do, that led to fixing the problem. All you have done is crow about your height (?), years of experience, and bash other peoples ideas that are different from you own. That is the worst kind of help.

You are miss leading people and you can keep your personal attacks to yourself.