Hesitation from idling

[trundletruc]

I am running a DJ engine with the pierburg 2E3 carb. The engine pulls well and ticks over steadily at 900rpm as spec. However, when I press the accelerator, from tick over, there is a momentary dip or hesitation. Not a major problem but does anyone know what is likely to cause this.(slow accelerated pump?) I don't think I would notice if I had not got a rev counter!
Carb has been meticulously cleaned and set up as per all the information I could find from various sources!

[DoubleOSeven]

For £0 you could pull the spark plugs and post up some pictures of them. The coil also, test with multimeter; primary & secondary windings. The HT leads, should be roughly 10k ohms per foot. Give the rotor arm & dizzy cap contacts a clean. No guarantee it’s the above, but it’s a free service that can’t hurt. Might get lucky.

[T25Convert]

Could be too much accelerator pump as well as too little. You could give it a tweak either way with it on the van and see where that gets you.

Could also be bust dizzy vacuum can, worth just checking it works if you give it a suck.

Have you checked timing?

[trundletruc]

Thanks for all your ideas. I will do some checking when I get time! Won't be the spark plugs though as they are new and I have just put them in.Will check the Accelerator pump first?

[kevtherev]

Another vote for accelerator pump delivery
And a question.
Does it hesitate when cold?

[trundletruc]

No, it does not hesitate when cold. Only after the engine has warmed up.
I have been trying various settings for the accelerator pump and it seems to make some change, but I still haven't stopped the hesitation. I 'm wondering if it might be something to do with the "progression slot"? wherever that is? (read this in some article)

[T25Convert]

Well assuming your pump doesn't have a split diaphragm if changing the injection volume doesn't cure the issue, its not that!

Progression ports are just holes in the throat - as you open the throttle plate it uncovers the holes, which allows the vacuum to suck additional fuel in through the holes. If your carb is clean and stock on a stock engine this is unlikely to be the source of your minor hiccup.

Air leaks can also cause hesitation - check for air leaks, missing vacuum hoses, open vacuum ports, duff temperature controller on the air filter box . If you have had the carb off did you use a very clean new gasket and torque down evenly?

Also if fuel system good and no air leaks, timing and timing advance would be the next thing I looked at....

[trundletruc]

People who replied to my original query might be interested to know I have solved the problem. By accident!
I had just fitted a DJ engine 2.1 engine to replace the 1.9 DG but running it on the Pierburg carb. Being a 1984 van it had the old exhaust system which fitted with no problems. However, wanting a SS system (unobtainable for the old system) I have fitted a complete later system. Hey presto the hesitation has disappeared!
I have no idea why this has happened but can guess that it might be to do with the fact that when I rebuilt the Pierburg 2E3 I took the best from the 2 carbs I had and swopped the top section of one and put it on the lower section of the other. There are slightly different numbers on the 2 tops. I can only think that although the 2 top sections look identical perhaps the jets you cannot get out are different or channels are different and the change came at the same time the exhausts changed?
However, I am very pleased, the engine behaves perfectly and there is no hesitation or conking out in traffic queues. I would be pleased to hear other people's opinions.
The change to the 2.1 has been really worthwhile and I have not experienced any increase in petrol consumption although I will be doing an accurate check over the next few months.