Oil & Fuel yanmar new injection pump wont pump

[Bthieman]

Help appreciated
I had the injection pump rebuilt by a reputable shop, installed, bled, and it wont pump
I tried priming by loosening the valve holder nut on each and it pumps when this happens, but wont pump when re-tightened
Since it is a mechanical pump on a 155d, it should be simple, but it defies me
I bought it non-op, but have replaced injectors, filters, checked compression and it should go
I would love to hear it run:cool2:
Please offer suggestions

 

[amaxwell]

I know almost nothing about diesel engines ,but understand there is a "timing" factor for injection pumps .Maybe a member that knows about this will chime in.

 

[normde2001]

Don't know what the "valve holder nut on each" is, but is it installed properly? does the rack move when you move the throttle lever? If you move the intenal plunger up against the spring, (like the cam does), does the spring restore it down.

 

[winston1]

Yanmar Tractor Fuel Bleeding Procedure

 

[California]

I went and read the Hoye procedure. I think that is for later Yanmars.

I'll add what I read here posted by Leonard and/or Danny, two experienced dealers. This has always worked for me:

On the YM Yanmars there are two bleeder screws at the top of the filter. You will bleed the system in the order that fuel flows through - filter input bleeder screw, filter output bleeder screw, then the one down on the injector pump inlet. Wait for pure fuel to come out of each before closing it and moving on to the next. Per those two experienced dealers there is no point to opening the hard lines at the injectors if you ran out of fuel. Any air bubbles will get purged into the cylinders anyway.

I'll add do the cranking with compression released - so you don't overheat the starter - while you are forcing air out of the lines. And the throttle has to be at max to send fuel up the lines.

This has always worked for me, and with only the single of gallon of fuel in the tank that I carried out to the tractor. I haven't found a need to fill the tank full as stated in those instructions.

Bthieman, I hope you find your issue is as simple as this.

 

[Bthieman]

hi All
Thanks for the suggestions.
It took 2 days to bleed all the air to the new injectors, but when I connected them to the delivery lines and checked for spray i got NONE.
It seems that it is not getting enough pressure from the new injection pump to the new injectors to run
How many shims should be under the injection pump? I have 2 copper shims and it seems that if I remove one it will increase the pressure. Any one have any other suggestions?
thanks
Gpa Bill

 

[California]

As I understand it the shims are unrelated to pressure. Rather, the number of shims controls how early/late the injector pump fires.

Just to be clear -

*With the lines snug nothing comes out the injectors at any point in the revolution of the crank.

* With the lines loose, fuel dribbles out at the right time as indicated by the timing mark on the front pulley. And it fires (dribbles) once per two crank revolutions.

* You are watching cylinder #1 (nearest the flywheel) to check for fuel delivery at the timing mark.

 

[winston1]

Don't know what the "valve holder nut on each" is, but is it installed properly? does the rack move when you move the throttle lever? If you move the intenal plunger up against the spring, (like the cam does), does the spring restore it down.

You never answered these questions posed by Normde? Are you confident the governor linkage is hooked up correctly to the injector pump rack?

 

[grainger12002]

maybe he got it going and went for a drive !!

 

[Bthieman]

Hi CA
Sorry for no reply earlier
I think the primary problem was that the fuel injection pump was binding on the speed control screw (has spring detent). When I removed that screw, the fuel was easier to remove, install. AFI in Modesto, CA is recalibrating it and I await its return. compression is 380, so I expect hard starting, but since I never got fuel out of cylinder injectors, I expect it to start. Do you know if a valve job would improve compression enough, since it is not that bad?
thanks
DD