Kubota Z751 injector pump

[Romario]

My engine doesn't start and I suspect the reason is the injector pump - i see very little fuel coming out of it, looks like something wrong with the pump.

Is there a diagram available of the pump anywhere? I suspect there is something wrong with the assembly, my mechanic changed the pump, but I don't think he did it right - I don't see increase in fuel coming out even if I do full throttle.

I saw people talking here a while ago:
http://www.orangetractortalks.com/forums/showthread.php?t=435

but didn't see anything posted

 

[North Idaho Wolfman]

You will see very little fuel coming out, that's normal, and it won't increase much to the eye on opening the throttle lever.
If there is fuel then it should run.
With everything attached and setup, bleed the lines at the injectors, if you get fuel then the injector pump is working.
Have you had the injectors checked/tested?
Have you had a compression test done?
Have you checked the valve adjustment?

 

[Romario]

You will see very little fuel coming out, that's normal, and it won't increase much to the eye on opening the throttle lever.
If there is fuel then it should run.
With everything attached and setup, bleed the lines at the injectors, if you get fuel then the injector pump is working.
Have you had the injectors checked/tested?
Have you had a compression test done?
Have you checked the valve adjustment?

I had the injector pump and injectors replaced.

Regarding the compression - it wasn't very good (200 as far as I remember), so I replaced the head with a new one. I checked the valves adjustment (if you are talking about clearance, I set it to 0.006)

 

[Alexisferos]

why you replace the head? does the pistons and the rings are ok? how was the cylinders?
if your pump and the injectors are new why to play with them?
check the lines if they have air and open a little bit more your valves 0.007-.009 inch, engine cold, cylinder at TDC. i would say that 0.008 is right for me.

 

[Romario]

why you replace the head? does the pistons and the rings are ok? how was the cylinders?
if your pump and the injectors are new why to play with them?
check the lines if they have air and open a little bit more your valves 0.007-.009 inch, engine cold, cylinder at TDC. i would say that 0.008 is right for me.

The compression was bad - that's why I took the head off. After I took it off I put some diesel into intake and exhaust of the head and one of the valves leaked. Mechanic friend of mine suggested I replace the head (redoing it would have taken more time and probably would be more expensive).

Lines are fine, I actually replaced them too .

I didn't take the pistons out, so I didn't see the rings. The cylinders looked ok - I didn't see grooves or anything unusual.

 

[North Idaho Wolfman]

Did you retest compression?
Usually a head problem will have only a minor effect the compression, but bad rings will have a major effect.

Are you pre heating the glow plugs?
When cranking are you getting any smoke?
Is it spinning fast?

 

[Alexisferos]

this engines are very easy to work with, and very simple to how they start up.
as you say you have change everything.
for me then check the tdc and preheat that baby for 40sec and start it up.

 

[Romario]

Did you retest compression?
Usually a head problem will have only a minor effect the compression, but bad rings will have a major effect.

Are you pre heating the glow plugs?
When cranking are you getting any smoke?
Is it spinning fast?

I didn't retest since I didn't have the equipment, it was tested by mechanic before.

I am preheating the plugs, I changed them as well, they are completely new and I checked the voltage on them and it was fine - 11.4 or so.

I am getting smoke when cranking. I wouldn't say it's spinning fast - seemed normal. There is a lever there that I can pull and it spins fast, I believe it's compression release lever. It was not in that position.

It made smoke as it was spinning.

 

[Romario]

this engines are very easy to work with, and very simple to how they start up.
as you say you have change everything.
for me then check the tdc and preheat that baby for 40sec and start it up.

I preheated for a while, I tried many things. That's why I suspect that's there is not enough fuel coming in, it looks like there is enough compression, but not enough fuel to start it.

I opened the "window" on the injector pump to see what's inside and when I pull the throttle all the way up I don't see too much movement.

I am attaching a pic how it looks like:

- on the right side you could see the "window" I talked about and I expected the throttle to move the pin there, but it didn't do it.

 

[Daren Todd]

TE=Romario;109462]

I am attaching a pic how it looks like:

- on the right side you could see the "window" I talked about and I expected the throttle to move the pin there, but it didn't do it.[/QUOTE]


Is the rack pin stuck/ frozen? Had that issue on mine. I had to spray the rack pin with some pb blaster and then carefully catch the ends with a flat screw driver and work back and forth. Since it's controlled by springs it doesn't take much to hang it up. When the pin goes to the right, it increases throttle, left will decrease throttle and all the way to the left will shut down the motor.
The root cause on mine was low oil pressure. Once i freed it up and fixed the low oil pressure, i haven't had an issue with it sticking

 

[Romario]

TE=Romario;109462]
Is the rack pin stuck/ frozen? Had that issue on mine. I had to spray the rack pin with some pb blaster and then carefully catch the ends with a flat screw driver and work back and forth. Since it's controlled by springs it doesn't take much to hang it up. When the pin goes to the right, it increases throttle, left will decrease throttle and all the way to the left will shut down the motor.
The root cause on mine was low oil pressure. Once i freed it up and fixed the low oil pressure, i haven't had an issue with it sticking

It was frozen before, that's why the pump was replaced. Right now it doesn't seem like moving the throttle moves it much, there is very little movement only when I move it all the way back to shut down the engine. That's the reason I think it wasn't installed correctly and that's why I am looking for a better diagram on how it should be done.

 

[Blkvoodoo]

If you're getting smoke, you're getting fuel. Battery voltage @ 11.4vdc is concerning, have you connected jumper cables from another vehicle (running) and tried to jump start ?

Battery state of charge should be over 12.3vdc, anything lower and you're under powering the starter and it won't spin properly ( and you risk burning it up )

11.4vdc is basically a dead battery

A slow turning Diesel engine won't build compression the way it should, not enough compression, not enough heat, no fire. Engine speed can also effect how hard the injection.pump pushes fuel thru the injectors, a good push, it'll spray (think how the wife's perfume atomizer works, very similar, but higher pressure) and light, a lazy roll over and it just kinda dribbles out, and the fuel gets smoked by the glow plugs. The glow plugs only help so much when they are on and hot ( they do not stay on when engine is running ) I suspect the smoke you see is the fuel hitting the glow plugs and flashing off.

 

[Romario]

If you're getting smoke, you're getting fuel. Battery voltage @ 11.4vdc is concerning, have you connected jumper cables from another vehicle (running) and tried to jump start ?

Battery state of charge should be over 12.3vdc, anything lower and you're under powering the starter and it won't spin properly ( and you risk burning it up )

11.4vdc is basically a dead battery

A slow turning Diesel engine won't build compression the way it should, not enough compression, not enough heat, no fire. Engine speed can also effect how hard the injection.pump pushes fuel thru the injectors, a good push, it'll spray (think how the wife's perfume atomizer works, very similar, but higher pressure) and light, a lazy roll over and it just kinda dribbles out, and the fuel gets smoked by the glow plugs. The glow plugs only help so much when they are on and hot ( they do not stay on when engine is running ) I suspect the smoke you see is the fuel hitting the glow plugs and flashing off.

The battery is fine, 11.4 was on the plugs, I think the voltage drops a bit.

The starter rotates fine, pretty fast, I had a new battery and topped it off with charger overnight.

How much fuel exactly there should be? I see only a small drop coming out each time the pump is pumping and I don't see the throttle moving the pin in the injector pump, hence my first question

The mechanic friend I worked with is pretty knowledgeable, his day job is fixing old expensive cars and we went through the things you are talking about here - checked the voltage, made sure the plugs are heating up, bled the fuel, etc.
He thinks the problem is with the throttle connection and there is not enough fuel coming in. He put the head together with me and he is pretty sure the compression should be fine there.

And to my first question - maybe someone has a diagram of the injector pump?

 

[Daren Todd]

Can you move the rack pin back and forth by hand? That should give you some idea where the issue is.

Going from memory, there are three springs to control movement. One from the throttle linkage to the rack pin. A short stubby one going from rack pin to crank case cover for the governor. And one to pull the rack pin back to the left. What tractor is this on?

 

[North Idaho Wolfman]

What model tractor is it in?
Or is it just a bare motor?
Send me a PM with an email address and I'll send you the WSM for a L185 and that was the motor they used in that model.

 

[Romario]

Can you move the rack pin back and forth by hand? That should give you some idea where the issue is.

Going from memory, there are three springs to control movement. One from the throttle linkage to the rack pin. A short stubby one going from rack pin to crank case cover for the governor. And one to pull the rack pin back to the left. What tractor is this on?

Yes, I can move it by hand, there is almost no resistance. There is a spring on the left side towards the flywheel, but the rack pin doesn't touch it unless I move it.

This is actually on a boat, but the engine is z751, it doesn't differ in injector pump area.

Here are some pictures (the bad one is me trying to explain what I see in Paint )

what i see

pump

levers

throttle

 

[Daren Todd]

That spring on the left should be attached. on the right hand side there should be two springs attached. One to the throttle linkage, one to the crank case cover. With out the one on the left, or the one attached to the throttle linkage, your throttle will not work properly. Let me know if i need to take some pics of the spring locations, and i'll pull the cover and get some when i get home

 

[Romario]

That spring on the left should be attached. on the right hand side there should be two springs attached. One to the throttle linkage, one to the crank case cover. With out the one on the left, or the one attached to the throttle linkage, your throttle will not work properly. Let me know if i need to take some pics of the spring locations, and i'll pull the cover and get some when i get home

Thanks a lot, that would be very helpful! How is the left spring attached? Is there a hole there? I only saw a cylinder and didn't see how it could be attached.

 

[Daren Todd]

Thanks a lot, that would be very helpful! How is the left spring attached? Is there a hole there? I only saw a cylinder and didn't see how it could be attached.

There was a little hole, can't remember exactly where. I'll pull the cover and will be able to let you know

 

[North Idaho Wolfman]

This might or might not shed some light on things.
I'm not sure what the second spring on the back of your drawing does????