Yanmar 3TNV76-Q injection pump question

[somanytractors]

My son has an excavator with a 3tnv76q in it.
It was kind of running but it would only move a few feet and bog down and stall. And then it quit running all together.
He pulled the injector lines and #1 was just dumping fuel out as soon as he turned the key on. 2 and 3 had quit pumping.
He brought the pump over and I got 2 and 3 working, but I cant get #1 to stop dumping fuel.
I know the pressure from the tank isn't enough to open the injector so I don't know if this is a problem or not but it is something I've never run into before.
I've never worked on a yanmar so I don't know whats normal or acceptable on this pump.

Is it normal for this to leak fuel into the line like this?
Do I need to get it stopped and if so how? I even pulled the parts out of the tops and swapped 1 and 2 and still # 1 was the one leaking so it seems to be something down in the body making it leak.

Any help is greatly appreciated!
Thanks
John

 

[stsid1]

My son has an excavator with a 3tnv76q in it.
It was kind of running but it would only move a few feet and bog down and stall. And then it quit running all together.
He pulled the injector lines and #1 was just dumping fuel out as soon as he turned the key on. 2 and 3 had quit pumping.
He brought the pump over and I got 2 and 3 working, but I cant get #1 to stop dumping fuel.
I know the pressure from the tank isn't enough to open the injector so I don't know if this is a problem or not but it is something I've never run into before.
I've never worked on a yanmar so I don't know whats normal or acceptable on this pump.

Is it normal for this to leak fuel into the line like this?
Do I need to get it stopped and if so how? I even pulled the parts out of the tops and swapped 1 and 2 and still # 1 was the one leaking so it seems to be something down in the body making it leak.

Any help is greatly appreciated!
Thanks
John

I know it's not the same but my brothers bobcat which has a Kabota motor was doing the same thing. He took his completely apart and cleaned it real well and put it back together and it fixed his problem. Apparently it had a speck of trash somewhere in the injection pump making it dump fuel out of his number one injector.

 

[bmaverick]

My son has an excavator with a 3tnv76q in it.
It was kind of running but it would only move a few feet and bog down and stall. And then it quit running all together.
He pulled the injector lines and #1 was just dumping fuel out as soon as he turned the key on. 2 and 3 had quit pumping.
He brought the pump over and I got 2 and 3 working, but I cant get #1 to stop dumping fuel.
I know the pressure from the tank isn't enough to open the injector so I don't know if this is a problem or not but it is something I've never run into before.
I've never worked on a yanmar so I don't know whats normal or acceptable on this pump.

Is it normal for this to leak fuel into the line like this?
Do I need to get it stopped and if so how? I even pulled the parts out of the tops and swapped 1 and 2 and still # 1 was the one leaking so it seems to be something down in the body making it leak.

Any help is greatly appreciated!
Thanks
John

See attached. Compliments of the YTOG,

main groups.io Group

*Yanmar Tractor Owners Group.* **US models, Gray market models, Cub Cadet models, RK models, even our green siblings known as Deere's. ** *A valuable source for owners of Yanmar tractors.* * * *If you would like to join our group, then click on the +Join This Group button below left. *NOTE: A...

yanmar-tractor-owners.groups.io

 

[thepumpguysc]

Mav, that download is for an MP style pump.. completely different than what the poster has..

 

[thepumpguysc]

Check to see if the insides where the springs are, goes up and down when u spin the gear..
Now make sure it goes left and right..

 

[thepumpguysc]

Take the solenoid off for the left and right test..

 

[somanytractors]

Take the solenoid off for the left and right test..

All that is working.
I found the problem accidentally.
While working with it I noticed that the one that was leaking #1 was about 1/8" taller then the other 2. If you look at the pic it's pretty obvious in hindsight.
It was tight but it was obvious that it wasn't in as far as the other 2. I pulled it out and the threads were pretty screwed up. I cleaned up the threads as best I could and then worked it in and out a bunch till I could get it in like it should be. Then I put it all back together. It seems to be working right now.
The pump isn't like it should be but I'm pretty sure it'll work fine for him. The threads seem to be holding just fine. If not he'll have to get another pump or figure out what to do about the threads.

Thanks again for your help

 

[somanytractors]

I know it's not the same but my brothers bobcat which has a Kabota motor was doing the same thing. He took his completely apart and cleaned it real well and put it back together and it fixed his problem. Apparently it had a speck of trash somewhere in the injection pump making it dump fuel out of his number one injector.

Thanks
It did have a bunch of rubber bits in it originally but that wasn't the problem with #1. I did find the problem though and I think it's fixed.

 

[somanytractors]

See attached. Compliments of the YTOG,

main groups.io Group

*Yanmar Tractor Owners Group.* **US models, Gray market models, Cub Cadet models, RK models, even our green siblings known as Deere's. ** *A valuable source for owners of Yanmar tractors.* * * *If you would like to join our group, then click on the +Join This Group button below left. *NOTE: A...

yanmar-tractor-owners.groups.io

Thanks, but wrong pump.
I believe I got it fixed.