B7100 fuel injector?

[Nlondon88]

I've got a B7100 that was operating perfectly until I let it run out of fuel. I filled up, bled the lines (probably touched something I shouldn't have) and now it seems like I'm only running on 2 cylinders or that the engine is getting too much fuel. Bogs down going uphill with lots of black smoke. 2 of the fuel lines from the injector seem to have good pressure, the 3rd does not. Any suggestions?

 

[Dave_eng]

I've got a B7100 that was operating perfectly until I let it run out of fuel. I filled up, bled the lines (probably touched something I shouldn't have) and now it seems like I'm only running on 2 cylinders or that the engine is getting too much fuel. Bogs down going uphill with lots of black smoke. 2 of the fuel lines from the injector seem to have good pressure, the 3rd does not. Any suggestions?

Tell us about how you bled the lines and which end of the line to each injector you opened. The injector end or the pump end.

Dave

 

[Nlondon88]

Tell us about how you bled the lines and which end of the line to each injector you opened. The injector end or the pump end.

Dave

I'm very new to tractors and diesel engines. At one point in time I probably adjusted every nut on the fuel line from the fuel filter to the engine. Everything I touched is all tight now but to bleed the lines and get it firing I adjusted the lines at the injectors (or closest to the engine) one by one to get the air out. 2 of those now will spray out if loosened. The 3rd has solid flow but does not spray.

 

[Dave_eng]

Are you using any manuals for learning how to do things. Your bleeding procedure bears no resemblance to what is in the Owners manual.

Go to this link and start downloading and reading.

Kubotabooks.com

Messing at the injection pump end of the lines is not good.

Dave

 

[Nlondon88]

Are you using any manuals for learning how to do things. Your bleeding procedure bears no resemblance to what is in the Owners manual.

Go to this link and start downloading and reading.

Kubotabooks.com

Messing at the injection pump end of the lines is not good.

Dave

No I just watched a couple YouTube videos. Thanks for the link! Pdf of owners manual will be handy.

Any diagnosis or suggestion on the power issue?

 

[85Hokie]

No I just watched a couple YouTube videos. Thanks for the link! Pdf of owners manual will be handy.

Any diagnosis or suggestion on the power issue?

Tell us WHAT you did - specifically, you by chance DO anything to the injector pump?

As you may have read now in the manual ............. take throttle wide open, loosen the bolt on side of the pump............ turn key ......... allow to bleed until NO bubbles..........

 

[Russell King]

Specifically did you turn any of the nuts on the lines at the injection pump? The ones on the lines up to the injectors. Did you turn or move the large nuts there?
If you did then you will probably have to get the pump repaired by a professional repair shop.

What happens when the tractor is running and you loosen the nuts on the fuel line at one injector at a time? Does the tractor run differently until you tighten the nut back up.

 

[Nlondon88]

Tell us WHAT you did - specifically, you by chance DO anything to the injector pump?

As you may have read now in the manual ............. take throttle wide open, loosen the bolt on side of the pump............ turn key ......... allow to bleed until NO bubbles..........

View attachment 73816
View attachment 73817

I did mess with the nut you circled here. I actually took it all the way out and put it back in but not while I was turning the ignition over. I tightened that nut back up then traced those lines above to the engine. I loosened those one by one while turning the engine over until no air was in the lines and the engine started. The tractor ran for about an hour but the whole time I could tell it didn't sound quite right and it didn't operate quite right.

 

[Nlondon88]

Specifically did you turn any of the nuts on the lines at the injection pump? The ones on the lines up to the injectors. Did you turn or move the large nuts there?
If you did then you will probably have to get the pump repaired by a professional repair shop.

What happens when the tractor is running and you loosen the nuts on the fuel line at one injector at a time? Does the tractor run differently until you tighten the nut back up.

I tried to turn those larger nuts just above the injector but they didn't budge and I didn't want to break them. One of them may have moved 1/8".

When I loosened the nuts up at the injector (I assume those are the ones closest to the engine) 2 out of the 3 would impact engine performance. When loosened one at a time those would cause the engine to falter. The 3rd one seems to have no impact on the performance of the engine but still has fuel flowing through it.

 

[Russell King]

That injector is probably bad and needs replacement or rebuild.

You can swap it into another position and see if that cylinder now is the one that has no effect when you loosen the nut on the injector.

I would just replace it and see if the problem is gone unless it is an expensive part.

 

[North Idaho Wolfman]

Pull all three lines off at both ends.
Pull all three injectors out, keeping not of their original location.
Crank the engine and watch the injection pump outputs, you should get fountains out of all three the same height.

If you don't get all three to output the same fountains: You'll need to get the injection pump out and either rebuild it yourself or have someone rebuild it.
I've done a lot of them it's not hard, but it requires some finesse.

If the fountains are the same:
Then connect up one line to the injection pump (doesn't matter which port) off the side of the engine. Install an injector to the other end, leave line slightly loose, then bled line and snug fitting.
Hold a piece of cardboard under the injector and crack the engine looking at the pattern, should be a mist/ fine spray.
If it drips or sprays course, you have a bad injector.
If you have a bad injector, do yourself and the engine a favor and replace all three at the same time.

 

[Nlondon88]

That injector is probably bad and needs replacement or rebuild.

You can swap it into another position and see if that cylinder now is the one that has no effect when you loosen the nut on the injector.

I would just replace it and see if the problem is gone unless it is an expensive part.

Starting to sound like the injector pump. Looks like those about about $500. Not cheap but not the end of the world I guess. Thanks for the advice!

 

[Nlondon88]

Pull all three lines off at both ends.
Pull all three injectors out, keeping not of their original location.
Crank the engine and watch the injection pump outputs, you should get fountains out of all three the same height.

If you don't get all three to output the same fountains: You'll need to get the injection pump out and either rebuild it yourself or have someone rebuild it.
I've done a lot of them it's not hard, but it requires some finesse.

If the fountains are the same:
Then connect up one line to the injection pump (doesn't matter which port) off the side of the engine. Install an injector to the other end, leave line slightly loose, then bled line and snug fitting.
Hold a piece of cardboard under the injector and crack the engine looking at the pattern, should be a mist/ fine spray.
If it drips or sprays course, you have a bad injector.
If you have a bad injector, do yourself and the engine a favor and replace all three at the same time.

Based on what you're saying I'm really starting to think it's the injector pump. I know for sure the flow is different on one injector. Any suggestions on resources for rebuilding the fuel injector pump? A new one looks to be about $500.

 

[85Hokie]

Based on what you're saying I'm really starting to think it's the injector pump. I know for sure the flow is different on one injector. Any suggestions on resources for rebuilding the fuel injector pump? A new one looks to be about $500.

Wait a minute .......... the machine was running fine BEFORE you ran out of fuel - yes?

IF that was the case, then I cannot imagine the pump going bad - you could have a bad injector but I would not blame the pump just yet. As others have suggested.......... MOVE the "bad" injector to another spot........ if the problem moves (all of this AFTER you bleed perfectly) then you know the injector is at fault....... IF the same spot (injector) does not work well, then it could be the pump. But I would not throw money at a new pump just yet. And IF you decide to get a NEW injector, do as others have mentioned .... buy 3 - and dont go and buy them from someone not Kubota or another branded name.

 

[North Idaho Wolfman]

Pull the lines off the injection pump outputs and do a fountain test.
It's not very uncommon for crud inside the injection pump (there is a reserve of fuel in them) to get sucked into the delivery valves when you run them dry.
If it doesn't fountain, send me a PM and I'll rebuild it for you, it usually takes about 20min to fix them when they do this.

 

[NicO]

Hoping it’s ok to add to this thread as im having similar issue…

Looking for up to date Fuel filter part number for B7100B. Went to Napa (Canada, BC) they cross-referenced fuel filter 3380: 040422BD1 but this was NOT the correct part.


I did NOT run out of fuel but machine was driving fine, turned off engine, went to turn back on again and engine struggled to get up to high RPM (took a long time) when it did, i put into 1st High gear and it bogged the engine and it almost stalled. Put into 3rd Low and it managed fairly fine to get back in from field. Turned it off, went to turn on again and it wouldn't start. I must be honest, my fuel filter upkeep has been poor since i bought machine 3 yrs ago so assumed it was either this or water in fuel. I drained the the tank and went to replace filter with the filter my local shop cross-referenced to be the same but turns out it was slightly wrong. I cleaned the filter (which didn’t seem overly too bad) and cleaned the filter housing. I drained the fuel and didn’t notice signs of water. Did a basic tank clean and put back together. I followed the bleed procedure in the manual for both filter and fuel pump…but still not starting.

After no success with that we moved past the pump to see if the injectors were receiving fuel so did a bleed at the pump end and the injector end. Two of the lines seemed to have a flow of fuel but one in particular seemed to always have bubbles coming out. The 3rd took a lot more time to receive fuel and when it did it seemed the fuel flow was minimal. Oddly, this 3rd injector seemed to get the machine closest to starting when cracking the nut/bleeding, but when tightening nut back up it went back to struggling. My automotive mechanic friend who was helping me seemed to think he’d expect more pressure from the pump at each of the injectors (He’s not got much experience in this type of machine though).

We removed the air filter and that made no improvement so no apparent issue there.

Our next planned move is to inspect the fuel lines after the fuel filter & replace as necessary.
Find the correct fuel filter & replace.

Wanted to try and establish why there seemed to be bubbles coming out of the line between the pump and injector but pump bleed port and fuel filter bleed ports seemed free of bubbles.

After reading this thread I plan on performing the fountain test on the fuel pump and swapping over the Injectors and looking for discrepancies/patterns.

One thing that i noticed, but not sure if it’s connected… Usually after warming glow plugs, starting, and running the tractor for a while, if I then shut the engine off for s short while I don’t usually need to re-heat the glow plugs to start, but the last few uses we had to warm glow plugs every time we started the tractor. Could this be a symptom connected to this issue??

Long post but figured its better to be as thorough as possible.

 

[NicO]

Pull the lines off the injection pump outputs and do a fountain test.
It's not very uncommon for crud inside the injection pump (there is a reserve of fuel in them) to get sucked into the delivery valves when you run them dry.
If it doesn't fountain, send me a PM and I'll rebuild it for you, it usually takes about 20min to fix them when they do this.

Hi, I have a B7100 based in Canada, BC.

If it comes to it and I have to rebuild the fuel pump do you have any tips, tricks, vids or shopping lists i will need.

Also, do you have any current part numbers for fuel filter, the one I bought was SLIGHTLY different dimensions and had metal at booth ends…the one currently in the machine only has a metal bottom.

 

[North Idaho Wolfman]

First look up inside of the filter housing as these filters are know for the metal ends popping off the filters when they are old and getting stuck in the top of the filter housing.
P/N 15231-43560 all of them have 2 metal capped ends.

As far as what your experiencing, sounds like you have a pump issue, not something you want to deal with without the proper tools and equipment to test and repair it.

FYI: You won't get any pressure out of the fuel injection lines, they need a closed system to build pressure.

When you remove the Injection pump, remove and save all of the shims under the pump as that set the timing.
You will simply reuse these shims with the rebuilt pump and the timing will be right.

I use Oregon Fuel Injection for all of my pump rebuilds.
I would also suggest you replace all three injectors while your at it.
They sell those too.
And test all there glow plugs.

 

[torch]

If the engine is running, it's easy to figure out which injector is affected. Simply loosen the line fitting on top of the injector, one cylinder at a time. If the engine rpm drops, then that injector is doing something. If it doesn't, you found the bad one. Now leave it cracked open for a few moments to ensure it is fully bled. If the rpm picks up when you retighten it then you "fixed" it.

Sometimes the little buggers just want more bleeding.

 

[NicO]

First look up inside of the filter housing as these filters are know for the metal ends popping off the filters when they are old and getting stuck in the top of the filter housing.
P/N 15231-43560 all of them have 2 metal capped ends.

As far as what your experiencing, sounds like you have a pump issue, not something you want to deal with without the proper tools and equipment to test and repair it.

FYI: You won't get any pressure out of the fuel injection lines, they need a closed system to build pressure.

When you remove the Injection pump, remove and save all of the shims under the pump as that set the timing.
You will simply reuse these shims with the rebuilt pump and the timing will be right.

I use Oregon Fuel Injection for all of my pump rebuilds.
I would also suggest you replace all three injectors while your at it.
They sell those too.
And test all there glow plugs.

Thanks for your great reply. That makes sense about the filter, I’ll pull it back out and swap it.

What sort of specialist tools do you need to re-build the pump? I wish there was a youtube vid on it (cough cough ).

We haven’t yet inspected the diaphragm part of the pump (not sure what it’s called) to see if that is the issue, would this make sense that it could be this is there was constantly air getting beyond the pump towards the injectors, and not being able to evenly push fuel to each of the injectors.