Stuck injection pump

[somian]

I have recently acquired a 4.5KVA SOM set, which has not been run for quite a few years, though I am not sure how many. It is not yet set up ready to run, but I have noticed that the injection pump control rack hardly moves. It moves freely but only for the tiny movement of the slack in the teeth, which suggests that the plunger is stuck inside. In fact the rack can be moved, but it is very stiff.

I therefore conjecture that fuel has dried in the pump and stuck it. Does anyone have a suggestion for the best way to free it. Will it free itself when I connect the fuel supply, or can I remove the delivery valve and put some knid of thin solvent in it?

Your suggestions please, because I can't think this is the first engine this has happened to.

Thank you,

Ian

[compig]

Remove it , soak it diesel for a day or so , then warm it up with a hot air gun until it's not quite too hot to touch , then try to move it !! Repeat as necessary.

[Combustor]

          Compiq's suggestion of soaking and heat/cool sounds good. I have also freed pumps stuck with veg oil or stale fuel by the following. Remove delivery valve and holder,
and and inlet banjo bolt, and use clean air to blow out any residual fuel. Refit pipe  and valve holder and fill both ports with acetone and allow to soak a while. Try moving
the rack and possibly tapping it back and forth very lightly with a soft hammer. The pump is easily removed without disturbing any settings so if the above fails, remove
it and try depressing the plunger. any vertical movement will also help the plunger to rotate via the rack. These pumps are fairlly simple and robust. Best of luck, Combustor.

[oliver90owner]

tapping it back and forth very lightly with a soft hammer

Add 'small' to that sentence.  The pumps may be quite robust but the teeth on the rack are quite fragile and it will be ruined if it gets broken.  I would use a lubricant with acetone if the pump is dry.  Oily petrol is probably just as good.

Personally, my first approach would be similar to Compig.

Regards, RAB

[Oilengines]

It is relatively easy to take out the bottom plunger and get diesel directly into the rack and element.

If the element itself is seized, then it will need a bit of specialist care to free off, which can be done with it outside the pump.

Pare

[MoeK]

I rebuilt both of mine on my CS twin. The engine was sitting outside for several years so both pumps were rusty.  I recommend the following steps. 

Remove the top nut, spring, and delivery valve if it is not stuck. Remove the banjo bolt and soak the entire unit in diesel, or  penetrating oil. I would let it soak for several days.  If you spray with penetrating oil, spray some into the fuel intake port and see if you can move the plunger vertically.You can do this by pressing on the bottom of the pump (where the tappet pushes). This will cause the oil to get inside the element and may assist by moving the a stuck plunger.

I would not recommend using excessive force, or hammering on the rack.

The other options is to take the pump apart to get at the element inside. This is fairly simple once you've done it once, but one needs to be very careful, and putting it together requires one to get the timing right. If you choose to go this way, I can  put together a longer note on how I went about it.

If you choose to take the pump apart, there are document scans of pump internals posted by "nobby" in the Gallery. They are very useful to learn about how the pump works.

Moe

[Shadow]

If the rack is moving even slightly you may have luck. The one on my CD is siezed and we have tried every imaginable solvent , it has been soaking in diesel and penetrating oil for 2 years now. The rack wont move nor will the plunger. But the good news was the new Listeroid type bolts right on. Good luck!

[Combustor]

              Yes, agree with the comments on applying very little force to the rack. An excellent article with good illustrations can be found by going to oldengine.org/
and selecting "Members Technical Items Index by Jeff Allen" ,then go to Diesel Injection Systems. It deals with the pump types found on most old listers.Regards, Combustor.

[Stan]

Somian...been there, done that...spent 2 weeks on and off working on it (see thread a year ago) and finally decided my time was worth more than the few bucks it would cost me to buy a new one, same make, same type etc. etc....  Still got the old one, one day when I'm out of things to do I'll go back to it.
Stan

[mike90045]

What about ATF fluid?  I've heard it's good for dissolving gunk. might be better than diesel. Set it in a black can in the sun, that will make some hot/cold cycles.

[981]

how do i find Nobby's photos?

[oliver90owner]

how do i find Nobby's photos?

Asking Nobby would be the easiest way to go.

[lowspeedlife]

how do i find Nobby's photos?

  Hi Charles, i think you are looking for the pictures in Nobby's lister engine gallery files, go to listerenginegallery.com & choose "user galleries" & click on Nobby's file. these are for a CD engine but that is what you have isin't it?

  Scott R.

[MoeK]

I believe the fuel pump drawings posted are for the same fuel pump used in the CS as well.

MOe

[somian]

I have freed off the injection pump from my Lister, but in doing so I have lost the relationship between the rack and the pinion.

I discovered that the pumping plunger was stuck in its sleeve, with the rack and the pinion both free to move within the small amount of slack. I soaked the pump in diesel fuel for many hours and was eventually was able to tap the plunger out from the top using a bronze drift through the delivery valve seat. Therefore I removed the plunger completely. At this point the pinion seemed to be held in by the spring seat, but suddenly I was aware that the spring seat and the pinion had fallen out. However the problem is that there is no alignment mark on the rack, or at least I can't find one. The only markings on the rack are the word stop and an arrow on one end, which is the end that sticks out most when the engine is not running.

I then cleaned everything, there being alot of sticky deposits around the rack and the pinion and in the pump chamber itself, that is the top of the bore of the main pump sleeve. However they are now clean and the plunger slides in the sleeve a treat.

Now the real question. What is the alignment of things. I deduce that the axial slot in the pump plunger should align with either then inlet hole or the one opposite it in the sleeve when the rack is in the stop position. Is this correct, and if so does it matter which of the two holes mentioned? With the mark on the pinion towards the rack, and the other mark on the pinion aligned with the mark on the plunger the slot is towards the hole in the main sleeve that is by the screw that holds the main sleeve in the body. This is plausible, but is it correct?

Your comments and guidance please.

Thanks,

Ian