Revs stick high - Pierburg issue?

[Smiffo]

Hi all.

Have a weird issue with the van, so lets start at the beginning:

1. Old Pierburg on van, worked OK but had a faulty choke mechanism.
2. While it was in for bodywork, I had the garage owner change it out for a 'new' one, so I had the choke mechanism working.
3. Van starts instant, runs and idles stable
4. All OK until you rev it up over 3500 - 4000 revs. If you do that it stays revving high even when you take your foot off accelerator.
5. Can't reduce revs UNLESS you turn ignition off.
6. Once ignition switched off and van stops, you can start it straight back up whereby it idles perfectly again.

This has all been advised to me as the van isn't here - chap thinks probably electrical because it resets once turned off, but it was OK before the carb change so I am more inclined to look specifically at the carb...

Question is, is there something mechanical at the carb that would reset after engine stops?
I'm thinking it must be something to do with vacuum or something... I was thinking vacuum goes when engine stops, and when restarted and revved up, the vacuum may effect something.

Let me know your thoughts.
I still have the old carb, so have a few spares I can utilise. I am just pondering the actual operational steps in the carb etc.

Lastly, the van isn't here so I imagine this will be a slow progress when I can try things.
It's pretty much stripped down now to the bare bones, but I want to start thinking about this before the paint is complete - I want it back as soon as possible..!!

Thanks in advance people - throw your theories out there.

[itchyfeet]

Second barrel interlock broken.

it opens by vacuum but has an interlock cam to stop it opening at low throttle position

yellow piece of plastic here, CJH sell them remanufactured but you can swap from your old carb, CJH will sell you the rivets.

[itchyfeet]

or swap choke from new carb to old carb may be easier.

[Smiffo]

Hard to get to itchy?

Am I going to have to remove the carb and use spares from this old one to rectify it?

[itchyfeet]

https://club8090.co.uk/forum/viewtopic.p ... hilit=chok" onclick="window.open(this.href);return false;

is the choke flap broken in old carb?
if not swap choke mechs.

you need to take carb off and split it I'm sure to change

starts about page 5 link above

ff

[Smiffo]

Top man Itchy..!!

I will make myself a brew and settle down to some reading...

[Smiffo]

Damn, I remember that thread - I posted on it..!!

I thought those bits were for the choke mechanism only?
Were you suggesting to repair that on my other carb, rather than look at what is actually wrong with the new one, Itchy?

P.S. Yes, choke flap missing on the old carb and the spindle just rattles about in there - that's why I changed it - now it seems to be a worse symptom with the new carb

Let me get the old one out and see if I can wrap my head round it for an hour or so.
Appreciate your input ( as always )

[itchyfeet]

Well you need to fix one of the other or better still, both so you have a spare, CJH has both plastic parts and so you can fix both.

Don't forget to do the adjustment of ths metal u tangs that go around the interlock, makes a big difference to hesitation on acceleration, also adjust accelerator pump and make sure the lever has no gap to the cam, again big difference to hesitation or flat spot.

all here

https://club8090.co.uk/forum/viewtopic.php?f=37&t=155368" onclick="window.open(this.href);return false;

ps where is your avatar gone?

[300CE]

Another thought aside from Itchy's Smiffo, you say she's had some bodywork done - has anything been taken out underneath the van (fuel tank?) - just wondered whether the accelerator cable may have become trapped?

If so, you maybe able to adjust the cable by removing the nearside indicator.

[Smiffo]

Another thought aside from Itchy's Smiffo, you say she's had some bodywork done - has anything been taken out underneath the van (fuel tank?) - just wondered whether the accelerator cable may have become trapped?

If so, you maybe able to adjust the cable by removing the nearside indicator.

Evening mate.

I wish
No, it definitely seems something odd with the carb, as the only way it can be reset is to turn the engine off.
( That shouldn't effect cable. ) This is what led me to think something vacuum related too.

I can double check with him but I'm quietly confident he would have checked the cable / throttle position returning to the correct position.

I'm going to dig out my old carb soon and tinker with it. I was planning on dismantling and rebuilding it for curiosities sake anyway - looks like fate has brought that date a lot sooner than I would have otherwise wished for..!!

Wishing I had never messed with it now. Dodgey choke I can live with - screaming up to lights at 4000rpm isn't

[Smiffo]

Well you need to fix one of the other or better still, both so you have a spare, CJH has both plastic parts and so you can fix both.

Don't forget to do the adjustment of ths metal u tangs that go around the interlock, makes a big difference to hesitation on acceleration, also adjust accelerator pump and make sure the lever has no gap to the cam, again big difference to hesitation or flat spot.

all here

https://club8090.co.uk/forum/viewtopic.php?f=37&t=155368" onclick="window.open(this.href);return false;

ps where is your avatar gone?

My Avatar went a few days ago LOL.
Changed it for a dancing Mona Lisa

Thanks for the link mate - more brews and more reading

E D I T - I looked up James' video earlier before posting, to remind me what I am in for ..!!

[Smiffo]

Well you need to fix one of the other or better still, both so you have a spare, CJH has both plastic parts and so you can fix both.

Don't forget to do the adjustment of ths metal u tangs that go around the interlock, makes a big difference to hesitation on acceleration, also adjust accelerator pump and make sure the lever has no gap to the cam, again big difference to hesitation or flat spot.

all here

https://club8090.co.uk/forum/viewtopic.php?f=37&t=155368" onclick="window.open(this.href);return false;

ps where is your avatar gone?

My Avatar went a few days ago LOL.
Changed it for a dancing Mona Lisa

Thanks for the link mate - more brews and more reading

E D I T - I looked up James' video earlier before posting, to remind me what I am in for ..!!

Right Then.

Dug the old one out and had a play - I think I see what you are thinking Itchy.

Makes sense. The below vid shows action where first barrel closes, it pushes second one closed. If that link is broken then it won't push the second barrel shut.

Then I suppose when engine stops, vacuum is removed and it closes on its own.

Am I thinking right?

https://vimeo.com/195697425


I should add, this is clearly my spare carb with the plastic bit intact. Funny, I removed my avatar with the link on the keyring from CJH's post, and a few days after removing it, I may actually need the real thing..!!

Once you give me the nod that I am not going insane, and I get to check my van and see the offending item to be sure, I will PM the man CJH to see if he has any left.

Sent from my iPhone using Tapatalk

[itchyfeet]

sorry no time to watch vid of a good one, show me a vid of pic of the broken one
yes flap opens by vacuum on hard acceleration or load and won't close becasue vac stays high at closed primary throttle.

been meaning to get somes spares myself from CJH

[Smiffo]

After all my p1ss taking lately, I deserved that
Might be a while before I get the faulty one back - there is a bit going on with the van at the moment.

I'm thinking I might dismantle the one I have here and get a good `feel` for the Pierburg.
Gonna end up stripping them whatever I think

[300CE]

Another thought aside from Itchy's Smiffo, you say she's had some bodywork done - has anything been taken out underneath the van (fuel tank?) - just wondered whether the accelerator cable may have become trapped?

If so, you maybe able to adjust the cable by removing the nearside indicator.

Evening mate.

I wish
No, it definitely seems something odd with the carb, as the only way it can be reset is to turn the engine off.
( That shouldn't effect cable. ) This is what led me to think something vacuum related too.

I can double check with him but I'm quietly confident he would have checked the cable / throttle position returning to the correct position.

I'm going to dig out my old carb soon and tinker with it. I was planning on dismantling and rebuilding it for curiosities sake anyway - looks like fate has brought that date a lot sooner than I would have otherwise wished for..!!

Wishing I had never messed with it now. Dodgey choke I can live with - screaming up to lights at 4000rpm isn't

No worries mate - carb strip down isn't too bad as have done the Weber (under the watchful eye of my mate as my mechanical skills aren't the greatest but have learnt a hell of a lot with my van . Pierberg shouldn't be to daunting. Keep us informed on how you get on