Fergie TEF missfire at idle

[MrNoo]

put the reduction box on it so u can rev faster

mine did basically the same b4 I stripped it , but mines still in bits id been blaming the slop in linkage and the diaphragm
I've a memory of reading about adjusting summin to counteract the hunt BUT I may be taking shite and wrong machine altogether captain .

No, you're quite correct and that is the rod to adjust to stop them hunting (if they do) my other half's one ticks over and runs like a swiss watch, never hunted at all after I rebuilt that.

 

[Mursal]

wasn't aware there was any pressure control on the actual lift pump

Have they not got a broken link between diaphragm and lift pump cam follower leg, so it just idles when the line pressure is reached. I'm guessing about 5 or 6 PSI.

 

[MrNoo]

Have they not got a broken link between diaphragm and lift pump cam follower leg, so it just idles when the line pressure is reached. I'm guessing about 5 or 6 PSI.

I will inspect, it is a new one, as replaced it as wanted to eliminate that.

 

[Mursal]

Addition port to eliminate hunting at tick over, click.
But I cant find the diagram in the article .........

Edit:
Found the diagram, its just the standard two pipe governor control found on the Power Majors, of little benefit to us.

 

[Mursal]

This may be of interest, the original question wasn't about hunting (or surging as he calls it) but the first answer goes into the setup procedure to reduce it, click

 

[MrNoo]

This may be of interest, the original question wasn't about hunting (or surging as he calls it) but the first answer goes into the setup procedure to reduce it, click

Yes, I have seen that before, I bet you there are very very few Fergies running where you can do that test and the "stop" plunger wouldn't move!! Mine takes circa 4-5 seconds to move back in, which I believe to be pretty good, certainly better than other engines I have worked on.
The only thing in the governor system that is not 100% right is that of the plunger, this was seized originally, and does have a very small amount of pitting but it moves freely (maybe too freely??) obviously the other side of this is a spring and another plunger type rod that goes up against the diaphragm. I can actually feel when the rod is in contact with the diaphragm if I move the side lever but as said before it makes no difference, instead just moving the "surging" higher up the rev range.
This is why I believe it maybe injector/pump related leading to a partial miss at low revs clearing when they rise, the partial miss upsetting the governor balance between the spring pressure on the diaphragm and the vacuum.
Certainly an interesting one!!!

 

[Right-arm fast]

Yes, I have seen that before, I bet you there are very very few Fergies running where you can do that test and the "stop" plunger wouldn't move!! Mine takes circa 4-5 seconds to move back in, which I believe to be pretty good, certainly better than other engines I have worked on.
The only thing in the governor system that is not 100% right is that of the plunger, this was seized originally, and does have a very small amount of pitting but it moves freely (maybe too freely??) obviously the other side of this is a spring and another plunger type rod that goes up against the diaphragm. I can actually feel when the rod is in contact with the diaphragm if I move the side lever but as said before it makes no difference, instead just moving the "surging" higher up the rev range.
This is why I believe it maybe injector/pump related leading to a partial miss at low revs clearing when they rise, the partial miss upsetting the governor balance between the spring pressure on the diaphragm and the vacuum.
Certainly an interesting one!!!

Try the tap to alter the speed the vacuum changes acting on the diaphragm, it may stop the cycle.

 

[MrNoo]

Try the tap to alter the speed the vacuum changes acting on the diaphragm, it may stop the cycle.

I have taken the caps off all the injectors this morn, loosened the locknuts and got my screwdriver out, very interesting listening to the pulses down through the screw driver, some are very metallic sounding pulses (where the injector fires) and I have one that is a tad on the intermittent side of things, I also adjusted the spring tension and the engine note certainly improved markedly, as in effect by changing the "pop" pressure this would also change the timing slightly too.
So I do wonder if I have found the issue…..!!! I will pop the new injectors in and see what it's like with those.
I did also note that on taking one of the caps off I had a fair flow of diesel emanating from the back of the injector where as the other 3 were damp but no drips etc.

 

[MrNoo]

Update, I just tweaked the adjusters on each injector until it sounded right, not very scientific but it is now running perfectly, no hunting/pulsing at all, like a little Swiss watch. Maybe not what the "book" or the experts say but it works, I guess you are pretty much fine tuning the timing on each cylinder by adjusting the pop pressure of each injector. Once I get the hydraulic pump back together I will stick the cultivator on and give it a bit of stick and see how it pulls.

 

[Right-arm fast]

I have taken the caps off all the injectors this morn, loosened the locknuts and got my screwdriver out, very interesting listening to the pulses down through the screw driver, some are very metallic sounding pulses (where the injector fires) and I have one that is a tad on the intermittent side of things, I also adjusted the spring tension and the engine note certainly improved markedly, as in effect by changing the "pop" pressure this would also change the timing slightly too.
So I do wonder if I have found the issue…..!!! I will pop the new injectors in and see what it's like with those.
I did also note that on taking one of the caps off I had a fair flow of diesel emanating from the back of the injector where as the other 3 were damp but no drips etc.

That's excellent. Did the injectors all need to be tightened or loosened or a mixture.Great fault diagnosis. The leak offs should only be getting wet - no flow as such, so the one injector sounds as though its nozzle/needle is worn which might be as much as anything a major contributor. Didn't you have those injectors reconned at the very beginning ?

 

[MrNoo]

Yup all injectors re-conned (or maybe I was!!) I had nothing to loose as have another set due next week, so took them out and stripped them down, couldn't really see any issues with them apart from bluing of the nozzles and also the lower portion of the needles. Put them back in, bled them up and then just adjusted each one. With too much spring tension you'd get a slight "knock" and too slack and you'd get it to "chuff" and emit smoke, so I settled somewhere in-between using my ears as a guide. It would be interesting to check them and see what pop off pressure they are running at now (should be 1750psi).
I did each one and then when it was running nicely I went through them again fine tuning yet further, and it is spot on, very smooth indeed. I will try it under load and see how it performs.

 

[tomlad]

Good man