Yanmar 3TN66UJ Injector Issues

[3TN66]

Hello all, I am new to this site and new to the Yanmar Motor. I recently rebuilt a Yanmar 3 cycl. 3TN66 for my JD F915 mower. I found that I had a bad injector pump so I took it to my local rebuild guy and the did their thing with all new parts. I just put the pump back in and started to bleed the lines. I got fuel to the pump but none coming out of the pump. I don't understand why. Any ideas guys? Is it I just need to crack the bleed screw and let it pump for a few mins while turning the motor over? Any help? I need to get this motor going my lawn is getting to the point of no return.LOL

Thanks,
Tim

 

[MJPetersen]

Now I am not familiar with your engine specifically, but Yanmar tractors have 3 bleed screws: 1) there are 2 bleed screws on the the filter bow itself; and then 2) there is a bleed screw on the pump itself. When I have run out of fuel, I just start at the filter bowl, when the fuel flows clean, then I move on. When I bleed the one on the pump and it runs clear without bubbles, then it starts and runs smooth. If I do not bleed the pump one, I can get it to start, but it will not run smoothly for a significant length of time.

Were I you, I would go through that series of bleed screws and then if it still does not pick up fuel, you can crack open the injector lines until you get fuel there. But that should not really be needed.

Best of luck there. And welcome to the TBN forum.

Mike

 

[3TN66]

MJPetersen thanks for the help. I have done all that, and no luck. I am going to try it all again tonight and see what happens, and if nothing again. I am going to take it to the shop that rebuilt the pump and have them get it started.

If any one else has any ideas of why I am not getting fuel out of a new rebuilt injector pump please chime in...

 

[MJPetersen]

I thought that you probably had, but I thought that I would start there anyway. You sound like a pretty knowledgeable guy so please do not take offense at my "simple" solution. It seems that there is an air lock there somewhere if no fuel is flowing through the pump. If there was fuel but it was not firing then I might suggest a timing issue or something similar.

Hope that you get it going.

Mike

 

[zzvyb6]

Are you certain that the injection pump was bad in the first place? Could be the transfer pump is not working and the Inj.pump is starved. Tech manual says to turn key switch on (don't crank the motor) and listen for clicking of transfer pump. Then bleed transfer line until fuel flows without bubbles. Then crack each inj.bleed screw and run fuel transfer until fuel appears without bubbles. I assume the injection pump timing is good and the fuel shutoff solenoid is working properly (mine sticks occasionally in the "off" position. You must manually push it open a few times to convince it to work. That causes my motor to look like the inj.pump is bad (fuel, but not enough pressure to work). And, you are not supposese to turn the delivery valve fitting when reattaching the lines or else "pump damage occurs". Also, did you install new shims? You are not supposed to reuse the old shims because "the timing will be way off".

 

[3TN66]

No offense taken on what you gave me earlier.



Nah it is not the transfer pump it is pumping good fuel to the Inj. Pump. In bleeding all the lines you can see a lot of fuel coming out of the line from the fuel filter to the Inj. Pump in side. I did replace the shims when I had the pump rebuilt. I put back the same thickness that was on it. No the solenoid I am not sure about. When I turn the key on it pulls it in. Seems like it turns on a magnet that pulls the rod back and when you turn the key off it releases it. Is the off position out or in? What kills me is even if the timing was off it should still be pumping fuel out of the pump, in my case no such luck. I am taking it to the diesel shop that rebuilt the pump and have them tell me why their newly rebuilt pump is not pumping fuel out of it. Suck a simple machine is causing me the most trouble. The pump was bad before b/c the fuel would go into the pump and when you should the key off it would drain all the fuel in it out the bottom and into the oil pan. I hope this shop can get it working. Thanks for the help guys, I am still open to any more ideas?