Fuel Return Pierburg 2E3?

[Worleyboy]

Lots to consider once more in these posts. Thanks for your time. I was sad not to find any direct evidence of gunge or water inside the carb, can still be a possibility. Will get going on Tuesday. Fit carb, check fuel and filters. Vacuum pipes, I've renewed end connections already. Earthing contacts, was there more? Will keep you informed.


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[itchyfeet]

A picture of your engine bay may help, sometimes you see something wrong from a picture, one of the van would be good too, we like van pictures

[Worleyboy]

Will co on return. Will be away for 36 hrs. Van not so pretty, faded red. Doubles as Summer tool storage room etc. but I love her!

[Worleyboy]

Rotten gaitor at fuel filler pipe was 6 years ago! But definily a lot of very fine sandlike stuff in the gas, I took off about a liter direct from the tank. Bottom half of filter badly gunged up. As only have a quarter tank of gas so I'm trying a few hrs through a CAV filter and external pump. I cant do a tank job now! Must get to the MOT on Monday! Will try a start later on today.


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[Worleyboy]

Pump filter setup

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[Worleyboy]

Started up ok, but needs adjustment after the carb rebuild, damn. M.o.t Monday hope to get nice tickover by then. Not quite my thing carburettas.


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[itchyfeet]

Also have you run the vehicle at idle until properly hot?
you could also try running at 2000rpm until properly hot by placing a brick on the throttle

run it at high revs until proper hot, then go give it a drive but don't go far, around the block until you have confidence, not far to tow home if it breaks down.

[CJH]

Started up ok, but needs adjustment after the carb rebuild, damn. M.o.t Monday hope to get nice tickover by then. Not quite my thing carburettas.

The two main adjustments, other than things which affect the choke, are:
1) The idle mixture screw, and
2) The accelerator pump

If you've replaced the accelerator pump diaphragm as part of the rebuild then that's probably ok - if it's not then you'll notice a flat spot when you pull away from rest.

The idle mixture screw is tricky to get to on a running engine, and really needs a gas analyser to set up properly, but the three carbs I've got experience with all seem to run OK with the screw set to 4 to 4.5 turns from fully closed. Did you touch that screw as part of the rebuild? If not, then:
- count the number of turns required to completely close the screw. This is so that you know how to put it back to where it was if you get in a muddle. Do this with the engine off.
- Then, from fully closed, wind it out 5 turns. Start the engine and run it till it's fully warmed up and the choke is fully off.
- Check the timing
- Adjust the idle speed to about 1000rpm
- wind the idle mixture screw in half a turn at a time until the revs drop, then wind it out half a turn.

That'll get you close. If the idle mixture isn't right at the MOT then that's the screw they need to adjust.

The other possible adjustments are mostly to the choke (pull-down setting, choke flap gap), but it's also possible to adjust the accelerator pump if you've got a flat spot when pulling away.

[Worleyboy]

Thanks CJH, clear and comprehensive info. Mot


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[Worleyboy]

M.O.T went well. Motor running ok when warm.


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[Worleyboy]

But the fast idle is way to high. Runs fine on starting but revs increase up to 2000 probably more, very annoying, decreaseing as choke warms up. Now I've read the instructions for fast idle adjustment from many sources now and its dead easy on paper, but I find just totally impractical in practice for various reasons! Now I reason that the screw can only go in or out. Which way do you turn it to bring the revs down if you want to do it by trial and error?


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[CJH]

Short answer: turn the fast idle screw anti-clockwise to lower the fast idle rpm. But unless you've adjusted this during a rebuild it's unlikely to be far wrong, and in your place I'd be checking for other things first. In fact the adjustment screw often has an anti-tamper cap on it from new, and rarely needs to be touched. There are a couple of things that affect the fast idle - I've taken some photos that should help explain how it's supposed to work.

With the engine off and cold, operating the throttle should set the cam to the very top step. This is because the bi-metal spring inside the choke housing (not shown in these photos, but its function is mimicked by the rubber band) pulls the cam round clockwise.


If you start the engine without touching the throttle it will idle very fast with the screw on this top step. If you have a working choke pull-down unit, then the moment you touch the throttle the choke pull-down will knock the adjustment screw off this top step onto the second highest step. At this point the engine speed should be around 2000rpm +/- 200 rpm.


Thereafter, every time you use the throttle the position of the cam will adjust to whatever the bi-metal spring dictates. it will work it's way down through the steps. When I adjusted mine I set it so that when it's on the bottom step the idle screw was just slightly off the end stop, so that the idle speed on this setting is just slightly above the hot idle speed. I note though that Kev suggested in another post that the idle speed at this point should be the *same* as the hot idle speed, so my guess as to how this should be set up was possibly wrong. But I don't mind the fast idle being a fraction high. You can just about see the small gap between the idle screw and the end stop in this photo.


Once fully hot and the choke bi-metal spring is unwound as far as it will go, the fast idle screw comes off the cam altogether, and your idle speed will be dictated by the idle screw. Up to this point though it will be dictated by the fast idle screw - you can see that they both control how much the throttle is opened.


If you feel that your fast idle is too high there are a couple of things to check before touching that screw. First, check that your pull-down unit is working - suck hard on the vacuum pipe and check that the arm moves back and forth. If it's not working then it won't kick the adjustment screw off the top step.

Second, check the position of the choke housing - adjusting it clockwise will make the choke stay on longer, and will make the fast idle adjustment screw stay on a higher step for longer.

[Worleyboy]

DG 1.9 1984
Thanks for the exellent photoes! I shall be studying the info. I didnt touch any adjustments untill after remounting the carb when I felt compelled to do something. I sussed out the anti clockwise for lower revs this afternoon and I think it is somewhat better now but of course I have to wait till tomorrow morning whwn its cold to see.
However I have just given myself another problem! Meaning to reniew the short piece of coolant hose going to the housing for the venting screw
I bust off the pipe stubb on the housing, see pick. Have plugged the openings, for the moment while I try to source a new one here in Sweden first.
Do you think it is safe for short trips?
Thanks again.

[Worleyboy]

Caravelle DG 1.9 1984
Coolant venting valve housing.

[Worleyboy]

New part on way, very expencive!