Hesitation from idling

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Hesitation from idling

Postby trundletruc » 12 Sep 2019, 19:10

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!
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Hesitation from idling

Postby DoubleOSeven » 15 Sep 2019, 12:32

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.
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Re: Hesitation from idling

Postby T25Convert » 16 Sep 2019, 09:16

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?
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Re: Hesitation from idling

Postby trundletruc » 19 Sep 2019, 18:02

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?
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Re: Hesitation from idling

Postby kevtherev » 29 Sep 2019, 06:04

Another vote for accelerator pump delivery
And a question.
Does it hesitate when cold?
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Re: Hesitation from idling

Postby trundletruc » 23 Oct 2019, 19:05

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)
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Re: Hesitation from idling

Postby T25Convert » 24 Oct 2019, 11:26

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....
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